CN1064166A - Signal conditioner - Google Patents
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- CN1064166A CN1064166A CN 91111200 CN91111200A CN1064166A CN 1064166 A CN1064166 A CN 1064166A CN 91111200 CN91111200 CN 91111200 CN 91111200 A CN91111200 A CN 91111200A CN 1064166 A CN1064166 A CN 1064166A
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Abstract
A kind of signal conditioner of the present invention for equipping by receiving unit, hop and power unit.The major function of these parts is digitized.Use common circuit block, a few signal conditioner (every kind is a hardware) just can be applicable to various sensors and topworks for difference in functionality.
Description
The present invention relates to oil refining, petrochemistry, steel-making, and industry such as papermaking in the signal conditioner (Signal conditioner) (also being signal converter (Signal converter)) that uses in the opertaing device of the multiple industrial processes that run into.
In the production run of industry such as oil refining, petrochemistry, steel-making and papermaking, to handle raw material and use fuel.In these processes, measure by sensor in temperature, flow rate (flow rate), pressure, liquid level water level (liguid level) and other parameters of the different parts of factory.By control executing mechanism (actuator) factory's utility appliance such as (as valves) above-mentioned parameter is remained in the proper range.This is for to come manufacturer industry product be very important to unify quality standard.For this control is provided, a kind of control system that mainly is made of computing machine is accepted extensively.
Figure 24 demonstrates the position of signal conditioner above-mentioned in above-mentioned control system.Provide signal conditioner 4 among the figure and be used for received signal, another signal conditioner 5 is used to send signal.The effect of these signal conditioners is at first described.Received signal is regulated the output signal SA that device 4 receives from sensor (transmitter) 6, and it is carried out arithmetic processing, to convert the form handled by the control module 1 that mainly is made of computing machine of being easy to.Send signal conditioner 5 and will convert the signal SB that is suitable for long-distance transmissions to, for example convert 4 to 20 milliamperes current signal shown in Figure 6 to from the control signal of control unit 1.
In the Process Control System field, be normally used two signals by signal SA that measures and the signal SB that is used for control executing mechanism 7.The electric current of these signals is generally in 4 to 20 milliamperes of scopes.In these signals, represent 0% for 4 milliamperes, and 20 milliamperes are represented 100%.For example, when producing 4 milliamperes of signal SA, claim that then institute's measuring pressure is 0 by measuring; When the signal SA that produces is 20 MAHs, then claim institute's measuring pressure to provide the full scale reading.If being used for the signal SB of control executing mechanism is 4 milliamperes, then valve is closed fully.If signal SB is 20 milliamperes, then valve is opened fully.Represent 0% and need not zero milliampere represent 0% reason to be and to distinguish cutting off 0 milliampere of electric current of transmission line generation and 0% with 4 milliamperes.Usually, can regard this 4 milliamperes to 20 milliamperes signal as low frequency signal, it slowly changes along with processed amount or actuating mechanism controls amount.
With reference now to Figure 24, the prior art of signal conditioner is described.Sensor 6 is contained in the pipeline (tube) that is arranged in Process Control System.For example, the pressure of contained liquid in sensor 6 measuring tubes, and pressure values is transformed into analog electrical signal SA.The simulating signal SA that received signal is regulated 6 inputs of 4 pairs of sensors of device carries out arithmetic processing, and signal transformation is become to be easy to the form that Be Controlled unit 1 is handled.The output of regulator 4 is transformed into digital form by analog-digital converter (ADC) 2 and offers control module 1.
Provide two examples that carry out arithmetical operation by 4 pairs of simulating signals of received signal adjusting device now.Its example one is to measure pressure by sensor 6, and this sensor converts measured pressure values to electric signal SA, for example between 4 to 20 milliamperes.For the control module 1 that mainly constitutes by computing machine, have only digitally encoded signal (be called for short down and make digital signal) to be understood by it.4 to 20 milliamperes simulating signal is to understand the Be Controlled unit.Usually, reply analog-digital converter 2 provides 0 to 5 volt voltage signal.If it is added one 4 to 20 milliamperes electric current, it can not change this electrorheological into digital form.So, received signal regulate device 4 to the simulating signal of its input in other words 4 to 20 milliamperes current signal SA carry out arithmetic processing, be transformed into 1 to 5 volt voltage signal.
Its example 2 sensor 6 here is temperature sensors, the sensor unit that is to use the electric heating coupling to constitute, and it produces several millivolts thermopower (power) as signal SA.Because this thermopower is a small voltage, converter 2 can not accurately convert it to digital form as input signal.Have, the amplitude and the temperature of thermopower do not have linear relationship again, so the not direct representation temperature of signal SA itself.Received signal is regulated device 4 will be amplified to the suitable level that can be converted device 2 processing from the thermopower of thermocouple.Then, signal SA, thermopower is converted into the signal that linear relationship is arranged with temperature in other words.This process is called linearization.
The signal conditioner of prior art has following shortcoming as constituted above:
(1) must have the signal conditioner of number of different types.Particularly need multiple sensors 6 and topworks 7 so that suitably control this factory.For example, with measure temperature sensor, measurement flow rate sensor and measure the sensor of pressure and factory in various particular locations link together.The value transform that each records with them becomes to have multi-form output signal separately, for example millivolt step voltage, 4 to 20 milliamperes electric current and 10 to 15 milliamperes electric current.So, for will be employed various simulating signals be transformed into a kind of signal through after the above-mentioned arithmetic processing, 1 to 5 volt voltage for example, received signal conciliation device 4 just need be applicable to each signal form of the output of these sensors respectively.In addition, a sensor needs one 24 volts direct currents (DC) power supply, and another sensor needs 4 milliamperes constant current source, or the like.As a result, the number of combinations of various power supplys and various output forms is too big.Like this, just must make signal conditioner 4 same type be arranged for different combinations.The control signal that is provided by control module 1 equally, also needs to be equipped with quite polytype transmission signal conditioner 5, because will be complementary with the signal form that the topworks that is connected requires respectively.In other words, in the prior art, must be equipped with various received signals respectively and regulate device 4 and various transmission signal conditioner 5.
(2) existing signal conditioner lacks dirigibility and is not easy to modification.In the process control field, technical indicator is can be reformed.Yet, having changed if handle the initial conditions (condition) and the output condition of the circuit of an analog input signal, the design of this circuit must change or some parts must be replaced so, to adapt to the change of input/output condition.In other words, the modification that the signal conditioner 4 of prior art or 5 can not adaptive circuit.Owing to this reason, when the condition that inputs or outputs changes, must be equipped with special-purpose hardware unit.Therefore, their variations of adaptive technique index promptly.
(3) signal conditioner of prior art is unsuitable for manufacturing the form of integrated circuit (IC).Because exist a large amount of parts, so can not realize microminiaturization.In the past, simulating signal that electrical measurement obtains and the simulating signal that is provided by sensor 6 or all pass through arithmetic processing from the simulating signal of control module 1 are to convert the input signal of desired form to.Though there has been the Analogous Integrated Electronic Circuits of simulating signal being carried out arithmetical operation, need input resistance, feedback resistance, electric capacity and other external parts to link to each other with these integrated circuit, therefore can not significantly reduce the quantity of parts.In other words, if they are made integrated circuit, can not get any benefit.Therefore, the existing signal conditioner that must finish the simulating signal arithmetical operation is not suitable for manufacturing the integrated circuit form.
(4) signal conditioner of prior art can not be adapted to have the sensor or the topworks of communication function suitably.In recent years, proposed a kind of requirement, required sensor and topworks to have communication function, so that more suitable process control to be provided.We describe a kind of sensor with communication function now.Common sensor measurement temperature, flow velocity, pressure, liquid level (liquid level) or other similar amounts, and it is transformed into 4 to 20 milliamperes low frequency signal.Sensor with communication function carries the information of the current measurement range of this sensor, this information be Process Control System send deliver to sensor by modulating wave.Utilize multiplex techniques that this modulating stage is delivered to control module 1 with above-mentioned low frequency signal.In other words, this sensor has intelligent function.This modulation can realize by frequency modulation (PFM), frequency shift keying (FSK) or additive method.
In order to adapt to this sensor that produces the signal that is loaded with multiplex communication information, its received signal is regulated device 4 must be equipped with detuner.Similarly, sending signal conditioner 5 must have a modulator, so that it is adapted to receive the sort of topworks of the signal that is loaded with multiplex communication information.As in above-mentioned (1), having described, must provide polytype.In addition, if for having or can not having the various sensors of multiplex communication information and the various combination of topworks is all paid attention to, the kind of signal conditioner has been too much really so.Therefore, they are not suitable for suitability for industrialized production.
The kind of the signal conditioner that an object of the present invention is to provide is few, such as has only a kind ofly, but can be applicable to various sensors and topworks.
Another object of the present invention is that the signal conditioner that provided itself can be adapted to revise when input/output condition changes, and does not need to change hardware and only to change software just passable.
Another purpose of the present invention provides a kind of signal conditioner, and its major part can be made into the integrated circuit form, and the components and parts that are attached to the integrated circuit outside are reduced in a large number.
The signal conditioner that a further object of the present invention provides, kind is few, (such as having only a kind of), but can be applicable to sensor or the topworks that is loaded with multiplex communication information, also can be applicable to the sensor or the topworks that are not loaded with many communication informations.
Because there are various sensors to link to each other with signal conditioner with topworks, must select to be suitable for from company's signal of sensor form and be suitable for connect the function switching signal of topworks's input signal form.Signal conditioner according to the present invention has the common hardware components of the major function finished.These functions are revised by software.
The receiver part of new signal conditioner each input signal of autobiography sensor in the future converts digital form to.Then, resulting digital signal is carried out various arithmetical operations, to separate and to extract value and the communication information that comprises in the input signal, these values are by measuring.The content of arithmetical operation can be changed by software under the commander of control module instruction.
According to the present invention, only need to be equipped with a few signal conditioner, that is to say, only just can be adapted to the sensor of quite a lot of kind, Sensitive Apparatus (sensor) and topworks with a few hardware.
By detailed description considered in conjunction with the accompanying drawings hereinafter, can understand signal conditioner better, thereby with easy to understand other purposes of the present invention and many attendant advantages.
Fig. 1 is the block diagram according to a kind of signal conditioner of the present invention;
Fig. 2 is the block diagram according to another kind of signal conditioner of the present invention;
Fig. 3 is the block diagram of the analog-digital converter that uses in the signal conditioner illustrated in figures 1 and 2;
(a) among Fig. 4 and (b) be the oscillogram of multiple signals;
(a) among Fig. 5 and (b) be that explanation FSK(frequency displacement is controlled) figure of modulation;
Fig. 6 represents by the signal that measures;
Fig. 7 represents the conversion usefulness of analog-digital converter and D-A converter and the relation of frequency;
Fig. 8 is the block diagram according to another kind of signal conditioner of the present invention;
Fig. 9 is the circuit diagram of several instantiations of input circuit 51 shown in power unit 92 shown in Figure 8 and Fig. 1,2,8;
Figure 10 is and the similar circuit diagram of Fig. 9, but in Figure 10, formerly switched to another state in the switch SW shown in Fig. 93, also done some modifications simultaneously;
Figure 11 is similar to Fig. 9, but has done some modification;
Figure 12 is similar to Figure 11, but has done some modification;
Figure 13 is similar to FIG. 10, but has done some modification;
Figure 14 is according to another signal conditioner of the present invention;
Figure 15 is the circuit diagram of power unit 92 shown in Figure 14 and peripheral part thereof;
Figure 16 is the sequential chart of the signal of inner each position generation of circuit shown in Figure 15;
Figure 17 is a kind of modification figure of circuit shown in Figure 15;
Figure 18 is the block scheme according to another signal conditioner of the present invention;
(a) of Figure 19 and (b) provide the sensor that produces the voltage output signal and the oscillogram of sensing unit;
Figure 20 represents the operation of DC/DC converter shown in Figure 8;
Figure 21 is a kind of modification figure of ADC52 peripheral circuits shown in Figure 1;
Figure 22 is the sequential chart that each position produces signal in the circuit shown in Figure 21;
Figure 23 represents the attenuation characteristic of two low-pass filters in the circuit shown in Figure 21;
Figure 24 represents the position of signal conditioner in a control system;
Figure 25 is the block scheme of DAC69 shown in Fig. 1,8,14,18.
Refer now to Fig. 1, provide a signal conditioner of the present invention among Fig. 1.This regulator (by 50 representatives of reference number) comprises control module 1, sensor 6 and topworks 7, and they are with to combine the counterpart that Figure 24 described similar.This signal conditioner 50 combines the function of analog to digital converter shown in Figure 24 (ADC) 2, the function of digital to analog converter (DAC) 3, the function that received signal is regulated device 4 and the function that sends signal conditioner 5.
This signal conditioner 50 also comprises input port P1, P2, P7, P8 and output port P3, P4, P5, P6.Corresponding to the receiving circuit of received signal adjusting device 4 shown in Figure 24 and analog to digital converter 2, between entry terminal P1, P2 and outlet terminal P3, P4.The transtation mission circuit part is corresponding to transmission signal conditioner 5 shown in Figure 24 and digital to analog converter (DAC) 3, between entry terminal P7, P8 and outlet terminal P5, P6.There is a line (not drawing among the figure) to be connected to sensor 6, to provide direct supply to it from signal conditioner shown in Figure 1.Be pointed out that power unit does not draw in Fig. 1.Topworks 7 provides electric current by external circuit 68.If described electric current is 4 milliamperes, then produce the output signal of 4 to 20 milli words.
Receiving circuit partly receives from the output signal of sensor 6 and communication information, and is sent to control module 1.The output signal of sensor 6 is pointed out the value that measures.The structure of this receiving circuit part is described now.Receiving circuit partly has an input circuit 51, and its effect is to change electrorheological into voltage, and transforming impedance.The circuit that electrorheological is changed into voltage can be realized by for example resistance.The function of transforming impedance can be obtained by operational amplifier.Specifically, in this mimic channel 51, convert the current signal SA that sensor 6 provides to voltage through a resistance R, it is amplified by variable gain amplifier shown in Figure 21 again.The gain of this operational amplifier is that the instruction according to control module 1 changes.When sensor 6 is a temperature measuring device that has a thermocouple inverting element, under the instruction control of control module 1, disconnect with this circuit as the resistance R (Figure 21) of current-voltage converter.Then, by operating switch shown in Figure 21 136, the gain of variable gain amplifier is switched to high value.According to the present invention, 51 of input circuits have been arranged minimum function, that is to say that it has only enlarging function.The digital signal processing part of hereinafter describing will be finished arithmetical operation.
When a new equipment of describing, suppose by the value that measures or actuating mechanism controls signal and communication information and made up (multiplexed) by multichannel, and suppose that this multichannel composite signal sees Figure 24 at control website 10() and Process Control System between transmit.This multichannel combination can be the frequency division system multichannel combination shown in Fig. 4 (a), also can be the time-devision system multichannel combination shown in Fig. 4 (b).In the frequency division system multiple tracks shown in Fig. 4 (a) combination, the low speed signal superposition of FSK modulating wave and 4 to 20 milliamperes together, this low speed signal indicates by the value that measures.In the combination of time-devision system multichannel shown in Fig. 4 (b), will be divided into many time slots (slot) time.For example, the FSK modulating wave is transmitted between t1 and t2 and in the time between t3 and the t4, and low speed signal was transmitted in the time cycle between t2 and t3.Frequency shift keying (FSK) is a kind of method of communicating signals, wherein represents binary zero and scale-of-two one with two different frequency f 0 and f1, in order to represent the information that will transmit, as shown in Figure 5.
In Fig. 1, provided the waveform that is transmitted signal of frequency division system multichannel combination.The ADC(analog-digital converter) 52 each analog signal conversion that made up by multichannel that input circuit 51 is provided become digitally encoded signal SC.For example, each instantaneous value of the amplitude of synthetic waveform m is converted to digitally encoded signal SC by the ADC52 order shown in Fig. 4 (a).So the information that digitally encoded signal SC contains (for example A1 and A2) has been indicated value that measures and the information of being carried by the FSK modulating wave (Fig. 5 (a)).
Above-mentioned digital signal processing part 61 extracts low speed component and modulated signals component (high speed signal component in other words) respectively from digitally encoded signal SC.These two components that extract are carried out digital signal processing, therefrom extract value that measures and the information that is transmitted.As an example, digital signal processing part 61 is made up of digital band-pass filter 53, digital demodulator 54, wave digital lowpass filter 55, measure portion 56 and other parts.For example, measure portion 56 is made up of digital computation unit 58, memory 59, table 60 and other parts.Detuner 54 extracts the information that is transmitted.Measure portion 56 is extracted by the value that measures.Can constitute a digital signal processor or similar devices by just now the digital signal processing part 61 that description constituted.The characteristic of parts 53-60 and function can be modified, and for example, can be revised by software.
Be added with interface 64 in the back of above-mentioned digital signal processing part 61, its Return Reception Dept. divides 61 output signal S1 and S2, and signal S1 and S2 are delivered to control module 1.That is to say that interface 64 matches each other the data type and the data transmission method of signal processing 61 and control module 1, thereby makes data S1 and S2 be sent to control module from the processing section.For example, interface receives serial data S1 from digital demodulator 54, it is transformed into parallel data S3 sends.In Fig. 1, every kind of data S3 and S4 are had only a signal wire, and every kind of data S3 and S4 are had only a photo-coupler (photocoupler) 65 or 66.In practice, many signal line and a plurality of photo-coupler are used in every kind of data combination.
Photo- coupler 65 and 66 is a kind of spacer assemblys, and it prevents from directly to be added on the control module 1 from the mistake large-signal of Process Control System.Photo-coupler 65 produces a received signal S5, the information that indication is transmitted.Photo-coupler 66 sends out a measuring-signal S6, indicates by the value that measures.
This equipment also comprises a transtation mission circuit part, and it receives actuating mechanism controls signal S9 and a transmission signals S8 from control module 1, and they are delivered to topworks 7.The information that signal S9 indication is transmitted, and the value that signal S8 indication reaches actuating mechanism controls.The structure of this transfer function part is described now.Photo-coupler 75 is similar with 66 to photo-coupler 65 with 76 operation and advantage.Specifically, these photo-couplers send signal S8 and S9 interface 78 to and provide electricity to isolate between them from control module 1.Interface 78 is also similar to above-mentioned interface 64 aspect operation and advantage.In other words, interface 78 makes data type and transmit between the transfer approach of data coupling mutually from control module 1 to the 2nd digital signal processing 70, thereby allows data S8 and S9 to be sent to signal processing 70 from control module 1.Consequently: data S10 shown in Figure 1 and S11 offer digital signal processing part 70 from I/O (I/O) end 73 and 74 of interface 78.Though the data S10 and the S11 that provide among the figure have analog waveform, in fact they are digitally encoded signals.
The 2nd digital signal processing part 70 receives two the digitally encoded signal S10 and the S11 of interface 78, and they are carried out arithmetic processing part 70 with digitally encoded signal S11 and another digitally encoded signal S12 addition (SUM up), produce the digitally encoded signal S13 of a combination.Digital signal S11 indication is to an amount (being equivalent to 4 to 20 milliamperes) of the action degree of control executing mechanism.And digital signal S12 represents the amplitude of modulated signals.For example, this digital signal processing part 70 comprises a digital modulator 72 and a digital adder 71.
In the example of Fig. 1, actuating mechanism controls signal S9 or S11 are directly delivered to digital adder 71, and do not do any digital processing.Also can carry out digital processing to this signal earlier with certain device.For example, in some cases, the control module 1 signal S9 that produces indication topworks's controlled variable (0 to 100%) becomes digitally encoded signal corresponding to 4 to 20 milliamperes by a logical block (not drawing among the figure) that comprises in the digital processing part 70 with this conversion of signals.
A DAC(D-A converter) 69 will be transformed into simulating signal S14 from each multichannel composite signal of digital signal processing part 70.In other words, transducer 69 is transformed into synthetic analog waveform m with digitally encoded signal S13, as shown in Figure 4.The information that this simulating signal m comprises has: for example corresponding to the information of level shown in Figure 4 (Level) A1 and A2, indicate topworks's controlled variable; For example also comprise the information that transmits by the FSK modulating wave corresponding to Fig. 5.
The actuating mechanism controls signal S11 that delivers to totalizer 71 is corresponding to 4 to 20 milliamperes in electric current.So in the output signal SB from output circuit 68, the FSK modulating wave is that superposition is on 4 to 20 milliamperes of low speed signals.The waveform of output signal SB is shown in Fig. 1.
The receiving circuit 7a received signal SB that in topworks 7, comprises, and extract amount (4 to 20 milliamperes electric currents) to wanting actuating mechanism controls, in order to promote last control device 76, for example, a valve.This receiving circuit also is used to separate the information that is transmitted of extracting that is in harmonious proportion.The actuating range of topworks 7 (range) is to select according to the instruction that is included in the information that is transmitted.
The operation of the equipment shown in Figure 1 that constitutes is by this way described now.At first, the receiving circuit part that comprises parts 51,52 and 62 is described.No matter the sensor 6 that links to each other with regulator has communication function or is not with communication function, this novel signal regulator 50 can both suitably be worked.The sensor that supposition is now connected has communication function.
More particularly, sensor 6 value (for example by the force value that measures) that will measure converts 4 to 20 milliamperes low speed signal to.With fsk modulated signal resultant low speed signal is carried out multiplexed (having constituted communication information in other words).And send out the signal that is produced from its output terminal.As an example, its communication modes is that half-duplex (halfdupex) FSK transmits (1200 baud).
At digital signal processing unit 61, digital band-pass filter 53 is used for extracting needed high fdrequency component (communication information component in other words) from the digitally encoded signal SC that introduces.Wave digital lowpass filter 55 is used to extract low frequency component (in other words by the value that measures). Wave filter 53 and 55 filtering characteristic can be regulated by software.For example, when the modulating wave that is comprised among the signal SA that is loaded with communication information is in different frequency range, can adjusts filtering characteristic and needn't revise hardware.The effect of bandpass filter 53 shown in Figure 1 is to extract high fdrequency component, and it is made of Hi-pass filter.
Yet, not as example shown in Figure 1, but there is multiple communication information to be transmitted, so, based on the following reasons, be necessary to use bandpass filter.Being provided with two kinds of communication information y1 and y2 will be transmitted.The centre frequency of the signal place frequency range that information y1 is modulated into for example is f
Y1The signal place frequency range centre frequency that another information y2 is modulated into is f
Y2Has frequency band f so need rejection filter to extract respectively
Y1And f
Y2Signal.
54 pairs of high fdrequency components from bandpass filter 53 of digital demodulator are carried out demodulation, and the result produces just like Fig. 1 and 5(a) shown in the digitally encoded signal of waveform S1.One of demodulation operation example is described now.A zero crossing (zerocrossing) detecting device that comprises in detuner 54 will be compared with zero point from the signal of bandpass filter 53.Then, during passing zero point, demodulate the FSK modulated signals.The communication information S1 that demodulation is by this way come out has passed through the I/O62 of interface 64 therebetween to deliver to control module 1, has also passed through photo-coupler 65.
56 pairs of digital low frequency components from lowpass wave device 55 of measure portion carry out arithmetical operation, obtain by the value that measures.These arithmetical operations are realized by digital computation unit 58.The data storage that produces in the necessary data of arithmetical operation and these operating process is in storer 59.Measure portion 56 has table 60.When the data-switching that will have a nonlinear relationship when needs became to have the data of linear relationship, just reference table 60.For example, the relation of the thermopower of thermopair and temperature can be put in this table,, just can be directly provide temperature value by the value of thermopower by reference table 60.Digital computation unit 58 can finish multiplication, calculate square, be averaged and other arithmetical operations.These arithmetic functions can be realized by known technology.For example, use and be averaged function, can obtain low frequency component (A1 and A2 among Fig. 4 (a)) mean value from the signal SA of sensor 6.The digitally encoded signal S2 of indication measurement value is sent to control module 1 via the I/O63 of interface 64, also delivers to photo-coupler 66.
The transmitter circuit part that includes parts 68,69,70,78 is described below.Control module 1 will transmit signal S8 and actuating mechanism controls signal S9 delivers to interface 78 via photo- coupler 75 and 76 respectively.Signal S8 and S9 are digitally encoded signals.Transmit signal S8 and indicate the information that is transmitted.Control signal S9 indicates the amount that will reach topworks's 7 controls.As a result, to be transmitted the signal S10(that data form shown in Figure 1 by a series of) delivered to digital modulator 72 by I/O73 from interface 78.Modulator 72 response signal S10 produce digitally encoded signal S12, and signal S12 indicates modulated wave amplitude.Though shown in signal S12 be analog waveform, in fact, be the digitally encoded signal of representing the modulated wave amplitude instantaneous.
Simultaneously, the I/O74 of interface 78 provides signal S11 to the second digital processing part 70, and signal S11 is the amount that topworks's indication control will reach.If just in time corresponding to 4 to 20 milli word currents, then digital signal processing part 70 can directly provide input signal S11 and needn't carry out arithmetic processing to it the digitally encoded signal that is produced by control module 1 to totalizer 71 as actuating mechanism controls signal S9.Yet, if the signal S9 that control module 1 produces only indicates the controlled amount of topworks (promptly from 0% to 100%), the arithmetical operation piece (not shown) that comprises in digital signal processing part 70 so converts signal S9 to corresponding to 4 to 20 milliamperes of signals digitally encoded signal.
Digital adder 71 produces signal S12 and S11 sum, and draws frequency multiplexing composite signal S13.The digitally encoded signal S13 that DAC69 will make up from each multichannel of digital signal processing part 70 converts the simulating signal S14 that contains two category informations to.A kind of information is pointed out topworks 7 is controlled the amount that will reach, and it is made of for example low frequency component corresponding to A1 among Fig. 4 and A2.Another kind of information is the communication information that is carried by the FSK modulating wave, and it is made of the high fdrequency component shown in for example Fig. 5 (b).
The receiving circuit 7a received signal SB that comprises in topworks 7 also starts final control element 7b with 4 to 20 milliamperes electric current.Receiving circuit 7a also provides communication information by demodulating process from the high fdrequency component that is transmitted signal, and the range (range) of topworks 7 is changed over the range of being indicated by communication information.
Though signal conditioner 50 shown in Figure 1 has been equipped receiving circuit and transtation mission circuit two parts, regulator also can have only one of them.Signal conditioner shown in Figure 2 just only is equipped with the receiving circuit part.
In above-mentioned example, the multichannel composite signal is the frequency division system modulation.Obviously, this novel signal regulator also transmits and receives measured value and communication information with time-devision system multiplex signal (Fig. 4 (b)).Specifically, obtain signal S1 from digital demodulator 54 between t1 in Fig. 4 (b) and the t2 and in the time period between t3 and the t4.Obtaining signal S2 from measure portion 56 in time period between t2 and the t3 shown in Fig. 4 (b).In in conjunction with the description that Fig. 1 did, the signal that provides between terminal P1 and the P2 is 4 to 20 milliamperes of low frequency signals that carry out the multichannel combination with modulating wave.Yet,, produce a faint thermopower as signal SA if sensor 6 relies on a Sensitive Apparatus that is made of thermocouple (thermocouple).Here the Sensitive Apparatus that produces this weak voltage signal SA links to each other with signal conditioner, and control module 1 provides a command signal to signal conditioner 50, resistance and input circuit 51 is cut off get in touch, and the resistance R here originally is used for the current-voltage conversion.So the gain of the variable gain amplifier that comprises in input circuit 51 also correspondingly is transformed into higher gain shelves (seeing Figure 21).
Analog to digital converter shown in Figure 1 (ADC) 52 is described below.Analog to digital converter can be divided into two big classes: instantaneous converter (flash converter) and approximate step by step converter (successive-approximation converter)." comparer, it is directly changed into input voltage the coded numeric value that approaches input voltage most in instantaneous converter use 2.This class ADC utilizes and follows the tracks of (tracking) analog-to-digital conversion.Specifically, be to follow the tracks of digital code like this, even it is the most approaching to get output voltage and this input signal of self-reference D-A converter.
If in ADC52, this two classes analog to digital converter is all used,, and be easy to make integrated circuit (IC) form just then this novel device can reduce its kind.Yet,, can obtain great benefit (as mentioned below) if in transmission contains the signal conditioner of signal of multichannel combined communication information, utilize over-sampling (oversampled) analog to digital converter.So, over-sampling a/d C is described below.
In recent years, in the process control field,, required the resolving power of 14 bit magnitudes for measuring 100 hertz the low frequency component (as the A2 among Fig. 4) of being lower than from sensor 6.On the other hand, the communication signal (see figure 4) frequency of combining with survey component multichannel is generally 10 kilo hertzs of orders of magnitude.The resolving power of 6 bits is considered to be enough to measure communication signal, as long as just because the content (as shown in Figure 5) that f0 and f1 can be distinguished from each other and come and can read communication signal.
Therefore, need one 100 hertz have 14 bit resolution and at 10 kilo hertzs of analog-digital converters with 6 bit resolution as the ADC52 in the equipment shown in Figure 1.Fig. 7 provides the relation of the frequency input signal of switch bit (binary digit) number or resolving power and this ADC.Usually, the number that converts binary bit (bit) in analog to digital converter to becomes reciprocal relation with frequency.In other words, the relation of the two is provided by the line L among Fig. 7.If have its feature of ADC such as Fig. 7 mid point B of given design
2Pointed, show that then this converter can be with A
3Bit comes inversion frequency at O and f
3Between simulating signal, the characteristic of another ADC is by a B
3Point out.
So,, then require an ADC 14 bits to be arranged and have a B at 10 KHz places if do not take measures
6The characteristic of pointing out just satisfies some B simultaneously
1(is 6 bits at 10 kilo hertzs of resolving powers) and some B
5(is 14 bits at 100 hertz of resolving powers).Yet this need will be better than family curve L(Fig. 7 of generally reaching greatly 10 kilo hertzs of characteristics that the ADC of 14 bits arranged).If by instantaneous formula converter or step by step asymptotic expression converter form produce this class ADC, equipment will become expensive huge so.
The present invention is to use a kind of over-sampling a/d C as ADC52, thereby has solved above-mentioned expensive and huge these two problems.Put it briefly, an over-sampling a/d C provides 3 times over-sampling rate for low-frequency signal components.Therefore, can be with the done with high accuracy analog to digital conversion.For high frequency component signal, over-sampling rate reduces, thereby A/D conversion accuracy has also reduced.In other words, according to the present invention, can realize 14 bit resolution at 100 hertz of places and 6 bit resolution at 10 KHz places simultaneously with single oversampling analog-to-digital converter.
This point that is described in more detail below.Fig. 3 provides a kind of structure of usual oversampling analog-to-digital converter, it corresponding among Fig. 1 by the piece 90 of dotted line.Usually, an oversampling analog-to-digital converter is the combination (see figure 3) of ∑-△ modulation system device 52 and filter level device 53,55, and these wave filters link to each other with the output terminal of modulator 52.In this manual, suppose modulator 52, thereby the circuit among Fig. 3 can be corresponding with the circuit among Fig. 1 corresponding to ADC52 shown in Figure 1.
Describe the operation of circuit shown in Figure 3 now, the output signal SG of input circuit 51 shown in Figure 1 is sent to prefilter 81 shown in Figure 3.This wave filter filters the frequency component that is higher than Nyquist (Nyquist) frequency (be sampling rate 1/2nd), with the pleat that causes that prevents to sample (foldover) noise repeatedly.The output of wave filter 81 is sampled by switch SW 2.One of characteristics of oversampling analog-to-digital converter are that its sampling rate is provided with enough highly, that is to say 10 times that are at least from the signal frequency of the main body of final measurement.The prediction waveform that analog adder 82 produces poor.Integration is carried out in the output of 83 pairs of totalizers 82 of integrator.Output from integrator 83 is compared device 84 quantifications.The output of comparer 84, the 1-clock delay unit 85 through being made of d type flip flop is sent to 1-bit DAC86.The indicated piece 52 of dotted line generally is called ∑-△ modulation system device among Fig. 3.This modulator makes its input signal SG be subjected to ∑-△ modulation, and produces modulated signal.The signal SF that is subjected to the modulation of ∑-△ with through instantaneous formula or the high resulting digital signal of near step by step formula analog to digital conversion certain species diversity is arranged, but the signal SF of this ∑-△ modulation is still and input signal SG is transformed into digital code obtains.Therefore, in this explanation, make ∑ shown in Figure 3 surely-△ modulator 52 corresponding to ADC52 shown in Figure 1.
Above described " certain species diversity " is described now.If ADC52 shown in Figure 1 by instantaneous formula ADC or step by step approximate expression ADC constitute, its output signal SC is corresponding to the digitally encoded signal of input signal SG with 1: 1 relation so.Output signal by bandpass filter 53 and low-pass filter 55 to extract high fdrequency component SD and low frequency component SE.Different therewith, if adopt over-sampling a/d C, the output signal SF of ∑ then shown in Figure 3-△ modulator is that input signal SG obtains through ∑-△ modulation.Like this, output signal and input signal SG do not have 1: 1 relation.In over-sampling a/d C, just after ∑-△ modulation signal SF is by digital filter, just obtain corresponding to the digitally encoded signal of input signal SG.More particularly, bandpass filter shown in Figure 3 53 produces digitally encoded signal SD, and it is with 1: 1 relation high fdrequency component corresponding to input signal SG, and the digitally encoded signal SE of low-pass filter 55 outputs with 1: 1 relation corresponding to low frequency component.Bandpass filter 53 shown in Figure 3 and low-pass filter 55 are identical with the corresponding component among Fig. 1.
In brief, converting high fdrequency component shown in Figure 5 to the 6 digital bits resulting signal SD that encodes, for example is that the signal SF with ∑-△ modulation extracts by bandpass filter 53.Equally, converting the low frequency component that measure to produce to 14 digital bit codes and the signal SE that obtains, for example is that the signal that this is modulated extracts by low-pass filter 55.
Specifically, when having utilized low- pass filter 55,4 to 20 milliamperes low frequency component is sampled with big over-sampling rate and is carried out arithmetic processing.So quantization error is little.Digitalized data is accurate.In other words, A/D conversion accuracy (for example 14 bit resolution) is determined by over-sampling rate.So, increase along with signal frequency reduces its over-sampling rate.As a result, simulating signal is to convert digital form to than high resolution.
On the other hand, the output of ∑-△ modulator 52 also can utilize bandpass filter 53 to convert digitally encoded signal to.Yet quantization error is big, because the above over-sampling rate of high frequency component signal is sampled and carried out arithmetic processing.Then data-switching is become digital form.As a result, the precision of numerical data is low.Like this, high fdrequency component is changed with for example 6 bit accuracy.By this way, in oversampling analog-to-digital converter,, be 6 bits, and at 100 hertz in the conversion accuracy of 10 KHz for example for the B1 point (see figure 7) of high fdrequency component, for example among Fig. 7 to the B5 point of low frequency component, its conversion accuracy is 14 bits.
In this example of description, with the ADC52 of an over-sampling a/d C as the receiving circuit part.By using the DAC69 of oversampling DAC as the transmission circuit part, can obtain similar benefit, promptly can obtain needed function economically.Figure 22 provides a common over-sampling number mould converter.The structure of ∑-△ modulator is similar to ∑ shown in Figure 3-△ modulator.
In in conjunction with Fig. 1,2,3 described examples, two wave filters are provided.Can provide more wave filter to select the multiple information of different frequency.In this case, as previously mentioned, can not use Hi-pass filter, must use bandpass filter as wave filter 53.In above-mentioned example, communication information is transmitted by the FSK modulation system.It is to be noted that modulation system is not limited to the FSK modulation.
In in conjunction with the describing mode that Fig. 1 and Fig. 2 did, suppose that sensor 6 links via 3 line transmission paths and signal conditioner 50.Specifically, except the line 101 and 102 that draws among the figure, also have a power lead (not shown) to link sensor 6 from signal conditioner 50.The power unit of signal conditioner 50 shown in Figure 1 has been omitted.
Sensor 6 connects via 2 transmission roads 91 in the structure that Fig. 8 provides.Structure shown in Figure 8 and similar shown in Figure 1, just signal conditioner 50 links to each other by 2 lines transmission road 91 with sensor 6, and has increased power unit 92, DC/DC converter 93, control circuit 94 and photo-coupler 96.Be noted that digital processing part 61 and 70 among Fig. 1, interface 64 and 78 all respectively by separately functional block representative, and these functions are represented by single square frame in Fig. 8.
The signal S16 that control circuit 94 provides according to control module 1 controls the output voltage V cc amplitude that DC/DC changes my device 93.The signal S2 that control circuit 94 receives from digital signal processing part 61, this signal S2 is by measuring.As an example, if be short-circuited in sensor 6, then signal S2 thinks exceptional value.In case detect this situation, then output voltage V cc reduces rapidly, to prevent undesirable power loss (power loss, electric leakage).
An example of description control output voltage V cc value method now.The closure time of the switch SW 5 of control circuit 94 control DC/DC converters 93 and the ratio of trip time, as shown in figure 20.So the electric power that provides to transformer T is controlled.The voltage that produces in the secondary side of transformer T changes with this ratio.
Figure 20 provides the closure state and the off-state of switch SW 5.When solid line raise, switch SW 5 was closed.In the situation of Figure 20 (a), obtained maximum output voltage Vcc.When switch SW 5 closed these time ratios increased, output voltage V cc reduced.If the closure state number is controlled at a ratio 3/8, shown in Figure 20 (c), then output power is limited in 3/8 of full power.
Suppose that sensor 6 can be loaded with the resulting value of measurement on the high frequency communication information,, as described in connection with Fig. 4, and can send out the information that contains this value by for example 4 to 20 milliamperes.
In the structure of Fig. 8, provide voltage or electric current to sensor 6 by the line of power unit 92 in 2 line transmission paths 91, and the signal that sensor 6 sends, value that promptly measures and communication information offer input circuit 51 via another line.
Fig. 9 provides an instantiation of power unit 92 shown in Figure 8 and input circuit 51 or output circuit 68.In Fig. 9, nearly all parts all are normally used, and switch SW 3 is switched between two different conditions.At a kind of state, the function of this structure is to provide electric power to sensor 6.Equally, it is also as the receiving circuit 51 that receives from the transmission signal of sensor 6.At another kind of state, this structure sends output signal SB as output circuit 68 to topworks 7.
Specifically link to each other with T2 with pair of outer terminal T1 with reference to 9, one transmission paths of figure.Input circuit 111 receives the electric current of the transmission path of flowing through, the perhaps electric current that flows through between terminal T1 and T2.In this example, resistance R is connected between terminal T2 and the common potential.Utilize resulting voltage drop to obtain the signal that is received.This input circuit 111 can be used other elements without resistive element R corresponding to the input circuit among Fig. 1 51.
Stabilizator (regulator) 112 is designed to both can be used for current constant mode and produces steady current to exterior terminal T1 and T2, also can be used for the constant voltage mode and produce constant voltage to these terminals.Stabilizator 112 is made of triode q1 and amplifier U1, and the output terminal of amplifier U1 links to each other with the base stage of triode Q1.The collector of this triode Q1 links to each other with DC voltage Vcc, and its emitter links to each other with outer terminal T1.
Mode change-over circuit 113 is made up of a setting device 114, signal output apparatus 115 and switch SW 3.These change-over circuit 113 bases and equipment ground, the place kind that exterior terminal T1 is connected with T2 are switched stabilizator 112 between constant voltage mode and current constant mode.
Divider resistance R1 and R2 are connected between outlet terminal T1 and the common potential.The signal that is received by the resistance R of input circuit 111 appears at signal and takes out terminal T4.Applying Signal Terminal T3 links to each other with the input end (+) of the amplifier U1 of stabilizator 112.One will send sensor 6 or the 7(of topworks to as shown in Figure 8) signal, be applied to this from control circuit 94 and apply Signal Terminal T3.
When the circuit with Fig. 9 came work as output circuit 68 shown in Figure 8, the described signal that will transmit was signal S14, and it is to be caused by the actuating mechanism controls signal S9 that control module 1 sends, or cause by communication information S8.In this case, signal output apparatus 115 shown in Figure 9 is also as DAC69 shown in Figure 8.
If circuit shown in Figure 9 is used to provide electric power and also is used for input circuit 51, the composition of the described signal that will transmit is: provide the voltage (such as 24 volts) or the electric current (such as 4 milliamperes) of power supply to the sensor 6 that is connected, and the communication information S8(that control module 1 sends sensor 6 to sees Fig. 8 and Figure 14).
The common port of switch SW 3 links to each other with another input end (-) of amplifier U1.Contact a1 links to each other with the node of divider resistance R1 and R2.Contact a2 links to each other with an end of the resistance R of input circuit 11.Switch SW 3 is started by setting device 114.
When switch SW 3 linked to each other with contact a1, divider resistance R1 was as the feedback resistance of amplifier U1.The input end (-) of amplifier U1 links to each other with common potential through resistance R 2.Consequently: stabilizator 112 is worked in the constant voltage mode, by 1+(R1/R2) given its magnification.
On the other hand, when switch SW 3 linked to each other with contact a2, because following reason, stabilizator was operated in the constant current way of output.As long as two input ends (+) and (-) of the amplifier U1 working properly of amplifier U1 in fact are in equipotential.If e is the voltage of setting up between two input ends (+) of amplifier U1 and (-).If Vout is the output voltage of stabilizator 112.Then following relation is set up:
Vout＝A·e
Here A is the open-loop gain of stabilizator 112, is generally 80dB.Because output voltage V out is for example 24 volts, then the e that is calculated by above-mentioned equation is approximately 0 volt.So if the control circuit from Fig. 8 94 provides a constant voltage Eo to terminal T3, then the contact a by switch SW 3 keeps providing this constant voltage to resistance R.Like this, just remain on and pass through an electric current on the resistance R, its size is given by Iin=Eo/R.Because this electric current I in provides from terminal T2, this steady current Iin is sent to the sensor that connects between terminal T1 and T2.Fig. 9 circuit of Gou Chenging can be worked under the first kind of mode or the second way by this way.Under first kind of mode, provide power supply to sensor 6, the circuit among Fig. 9 is as the input circuit 51 that receives from the transmission signal of sensor 6.Under the second way, this circuit is as output circuit 68 work of sending output signal to topworks 7.This two kinds of working methods are described respectively below.
(first kind of mode: provide constant voltage to sensor 6, and Fig. 9 circuit is as the circuit that receives from the current signal of sensor 6.) Figure 10 provides the connection layout of setting up this first working method.The relation of each parts shown in Figure 10 and each parts shown in Figure 8 is described now.The exterior terminal T1 of Figure 10 is corresponding to the terminal P10 of Fig. 8.The exterior terminal T1 of Figure 10 is corresponding to the terminal P10 of Fig. 8.The exterior terminal T2 of Figure 10 is with should be in the terminal P1 of Fig. 8.The part of being made up of stabilizator 112, resistance R 1, R2, switch SW 3 and mode commutation circuit 113 among Figure 10 is corresponding to the power unit among Fig. 8 92.The input circuit 111 of Figure 10 is corresponding to the input circuit 51 of Fig. 8.Power source voltage Vcc shown in Figure 10 is corresponding to the output voltage V cc from DC/DC converter 93 shown in Figure 8.
Sensor 6 is connected between the exterior terminal T1 and T2 shown in Figure 10, sends current signal Iin via transmission path 91.Setting device 114 links to each other switch SW 3 with contact a1.Like this, the Voltage Feedback that is branched away by divider resistance R1 and R2 is to the input end (-) of the amplifier U1 of stabilizator 112.Stabilizator 112 is worked under the constant voltage way of output.Signal output apparatus 115 is delivered to given voltage signal Vi another input end (+) of amplifier U1.Like this, externally the output voltage V out that produces between terminal T1 and the common potential remains constant voltage, and for example 24 volts, corresponding to the voltage signal Vi that provides by stabilizator 112.In other words, the output voltage V out that occurs at terminal T1 is by formula
Vout＝Vi·｛1+（R2/R1）｝
Given.
Sensor is controlled the electric current of the transmission path 91 of flowing through according to the process control amount, thereby has added a process control signal at terminal T2.Specifically, this process control signal, electric current I in transmits through transmission path 91 in other words, and the resistance R of input circuit 111 of flowing through is so produce a voltage Eout corresponding to the process control amount.This signal Eout takes out terminal T4 from received signal and extracts, thereby and is amplified the voltage signal SG that produces suitable amplitude by the amplifier (not shown).The signal of this amplifier output is provided for the ADC52 among Fig. 8.
(second way: the circuit among Fig. 9 is as the circuit that sends current signal to topworks 7.In other words, this circuit is as output circuit 68.) Figure 11 provides the connection layout of setting up this second way.The relation of parts shown in Figure 11 and parts shown in Figure 8 is described now.Exterior terminal T1 among Figure 11 is corresponding to the terminal P5 among Fig. 8.Exterior terminal T2 among Figure 11 is corresponding to the terminal P6 among Fig. 8.Output circuit 68 that should be in Fig. 8 during the part that constitutes by stabilizator 112, resistance R 1, R2, switch SW 3 and mode commutation circuit 113 among Figure 11.Signal output apparatus 115 among Figure 11 is corresponding to the DAC69 among Fig. 8.Power source voltage Vcc shown in Figure 11 is corresponding to the output voltage V cc from DC/DC converter 93 shown in Figure 8.
Topworks 7 is connected between exterior terminal T1 and the T2 by transmission path 95.Setting device 114 is linked contact a2 with switch SW 3.Like this, resistance R is linked the output terminal (-) of the amplifier U1 of stabilizator 112 as a feedback resistance.Stabilizator 112 is operated in the constant current way of output.At this state, the signal Vs that send topworks 7 to is added to terminal T3, and it links to each other with another input end (+) of amplifier U1.Like this, stabilizator 112 is controlled output current Iout according to signal Vs, and this electric current I out is delivered to topworks 7 from exterior terminal T1.This output current Iout is by formula
Iout＝Vs/R
Given.
Like this, though the circuit working among Fig. 9 in the above-mentioned first kind of mode or the second way, this circuit can both use identical critical piece.And, can realize the conversion of working method by mode of operation change-over circuit 113 at an easy rate.
In above-mentioned example, typical sensor 6 and topworks 7 are interconnective (interconneced).In this scope, will produce the sensor of voltage signal or sensitive element and be added in the middle of the above-described parts by the topworks that this voltage signal drives.Circuit shown in Figure 9 can be adapted to add the situation of these sensors, sensitive element and topworks.Be described in the operation of finishing under this situation below.
(circuit of working method: Fig. 9 is as the input circuit of the voltage signal that receives self-sensing or sensitive element to send.〕
The example of these sensors such as sensitive element is shown in Figure 19 (a) and (b).The situation of the sensitive element that is made of thermocouple is adopted in Figure 19 (a) expression.The voltage Vp that this thermocouple adds one several millivolts to exterior terminal T1 and the T2 of Fig. 9.This thermocouple does not need power supply.
The situation of a pot (potentiometer) as sensor used in Figure 19 (b) expression.Drive potentiometric sliding contact according to the process control amount.In this case, must be generally 4 milliamperes from the steady current Iout(of signal regulator) offer pot.As a result, pot provides the given voltage by formula Vp=rp Iout to exterior terminal T1 and T2, and rp is potentiometric resistance here.When thermocouple or pot were linked to each other with T2 with exterior terminal T1, the connection of Fig. 9 circuit and design were as shown in figure 12.
The operation of being finished when exterior terminal T1 among Figure 12 links to each other with T2 when thermocouple shown in Figure 19 (a) is at first described.In this case, thermocouple links to each other with signal conditioner.Control circuit 1 makes mode setting device 114 that switch SW 3 is linked to each other with contact 92.Like this, resistance R links to each other as the input end (-) of feedback resistance with the amplifier U1 of stabilizator 112.Signal output apparatus 115 is added to another input end (+) of amplifier U1 with signal Vis, to cut off (cut off) stabilizator 112.Because triode Q1 is biased by (biosed off), so do not power to thermocouple from exterior terminal T1.In this way, taken out the voltage signal that sends via transmission path 91 by the thermocouple of Figure 19 (a) from the terminal T5 that links to each other with exterior terminal T1, with this as voltage Vout,
Vout＝Vp（R1+R2）/（R+R1+R2）
The voltage Vout that occurs at terminal T5 is amplified by variable gain amplifier (by the expression of 131 among Figure 21) and delivers to ADC52 shown in Figure 8.
The operation of being finished when exterior terminal T1 among Figure 12 links to each other with T2 when pot shown in Figure 19 (b) is described below.In this case, pot links to each other with signal conditioner.Situation during with the use thermocouple is identical, and setting device 114 links to each other switch SW 3 under the control of control module 1 with contact a3.Signal output apparatus 115 is added to voltage Vis the input end (+) of amplifier U1.The Vis magnitude of voltage is provided by formula Vis=4 milliampere R.In other words, stabilizator 112 is as the constant current source that 4 milliamperes electric current is provided.So pot is added to voltage (4 milliamperes of Vp=rp) on exterior terminal T1 and the T2.Situation during with the use thermocouple is identical, takes out this voltage Vp as voltage Vout from terminal T5.
Above-mentioned voltage Vout representative of taking out from terminal T5 is from the potentiometric output signal Vp of thermocouple type.Like this, the circuit of Fig. 9 can be adapted to sensor or the sensitive element that thermocouple or pot etc. produce voltage signal, and does not need to change basic circuit structure, as long as with simple direct mode operation setting device 114.
(circuit of working method: Fig. 9 is as the output circuit 68 that the constant voltage control signal is provided to topworks.) for driving topworks 7, must add a voltage signal (for example Vout=1 to 5 volt) to it.Circuit among Fig. 9 connects into appearance shown in Figure 13.For example it works under voltage signal 1 to 5V drives the 7(of topworks) be connected between exterior terminal T1 shown in Figure 13 and the T2.In this case, setting device 114 links to each other switch SW 3 one contact a1 under from the control of the instruction of control module 1 shown in Figure 8.By the input end (-) of the Voltage Feedback of resistance R 1 and R2 dividing potential drop, so stabilizator 112 is worked in the constant voltage mode to amplifier U1.Because voltage Vs is added to another input end (+) of amplifier U1 through terminal T3, from the output voltage V out of stabilizator 112 by formula
Vout＝Vs·｛1+（R1/R2）｝
Provide.In other words, from control circuit 94(Fig. 8) a voltage signal be added to terminal T3(Figure 13) on, for example above-mentioned Vout is assumed to 5 volts.
In the description of doing so far, done supposition R＜＜RA, the RA here is the interior resistance of topworks 7.Because resistance R can not be ignored, the voltage of setting up between the two ends of resistance R is taken out (seeing Figure 13) is added to amplifier U1 input end (+) in order to correction voltage Vs value from terminal T4.Like this, the circuit of Fig. 9 can be provided with 114 by direct control with same circuit structure and comes the processes voltage signal.
Figure 14 provides a kind of connection example, in this example the composite signal of low frequency signal (as DC power supply signal or measurement gained signal) with modulated wave or communication information is sent out by two wires transmission path 91.Relation between the structure of the structure of Figure 14 and Fig. 8 is described now.Do not use the output circuit 68 among Fig. 8 in the structure of Figure 14.Output S14 from DAC69 among Figure 14 is sent to power unit 92.
With reference now to Fig. 9, interconnecting of power unit 92 among Figure 14 described.Control circuit 94 among Figure 14 is added to terminal T3 among Fig. 9 with signal S17.DAC69 is corresponding to the signal output apparatus among Fig. 9 115.Shown in Figure 8 interconnecting can easily change over shown in Figure 14 interconnecting under control module 1 instruction control.Certainly, circuit block shown in Figure 14 is identical with circuit block among Fig. 8.
The working condition of signal conditioner 50 shown in Figure 14 is described now.Sensor 6 among Figure 14 must provide a constant voltage by direct supply, for example 24 volts.Suppose that the sensor 6 among Figure 14 can receive communication information M1, this communication information be by the high frequency waves of superposition on these 24 volts of voltages in other words modulating wave carry.Suppose that also sensor 6 can send the composite signal of 4 to 20 milliamperes of low frequency signals and communication information M2 to input circuit 51, this communication information is by the composite signal of high-frequency signal and communication M2, this communication information is carried by high-frequency signal or modulating wave, and this low frequency signal is by measuring.One of the communication information M1 that is sent to sensor 6 by signal conditioner 50 example is the instruction about the measurement range of revising sensor 6.One of the communication information M2 example that is sent to signal conditioner 50 by sensor 6 is the information that the above-mentioned communication information M1 of response points out measurement range.
In this case, the power unit among Figure 14 92 connects into appearance shown in Figure 10 under the control of control module 1.Stabilizator 112 sends a constant DC voltage (Vout=24 volt) by exterior terminal T1.Control module 1 produces and is transmitted signal S8.For example, it has sent out numerical information M1, points out the measurement range L1 of sensor 6.
Be transmitted signal S8, or communication information, producing by control module 1, indication measurement range L 1 offers digital signal processing part 70 with this signal via photo-coupler 75 and interface 78.Then, this signal is become digital modulation signals S12,70(sees Fig. 1 in the processing section) the inner communication information M1 that represents.Give DAC69 with signal S12 through totalizer 71.
DAC69 converts the digitally encoded signal of digital modulation to analog signal form, for example the FSK modulating wave of describing in conjunction with Fig. 5.Give power unit 92 with the simulating signal that is generated.The voltage signal Eo that is used to produce 24 volts of direct currents is sent to the input end (+) of the amplifier U1 of power unit 92, and its connected mode as shown in figure 10.Equally, DAC69, promptly signal output apparatus 115, and (Fig. 5 (b) delivers to same input end (+) with high-frequency signal.As a result, superposition is had Fig. 5 (b)) deliver to same input end (+).As a result, the constant 24 volts of DC voltage that superposition had a high-frequency signal shown in Fig. 5 (b) by transmission line 102 by terminal P10(Figure 14) offer sensor 6.
Sensor 6 is powered by 24 volts of direct currents that transmission line 102 provides.Sensor carries out demodulation to the modulated wave of superposition on direct current, and its range is arranged to the indicated measurement range L1 of communication information M1.The value that sensor 6 will be measured in this scope converts 4 to 20 milliamperes low frequency signal to, and electric current I in is delivered to exterior terminal T2 shown in Figure 10.Electric current I in is superimposed to the high-frequency signal of indicative of settings measurement range or modulation wave signal on the low frequency signal to form.Convert the electric current I in that this contains this two classes signal combination to voltage signal by resistance R, and appear at terminal T4.Then, this voltage signal is exaggerated the amplification of device (not shown) and gives ADC52.
This signal is by after the ADC52, and photo-coupler 65 produces a high-frequency signal S5, the measurement range that indication sensor 6 is set.Photo-coupler 66 produces measuring-signal S6, the value that indication is obtained by sensor 6.This operating process was described in detail in conjunction with Fig. 1.
When signal conditioner 50 connects as shown in figure 14,, just can realize the supply of direct supply, the transmission and the both-way communication of measured value simultaneously as long as control module 1 or signal conditioner 50 are interconnected with sensor 6 by two transmission lines.Have again, structural modification can be become structure shown in Figure 14 and do not need the structure of Fig. 8 is increased circuit block.Can easily finish this modification according to control signal from control module 1.
The course of work of this structure of perhaps beyonding one's depth is because must be simultaneously with reference to Figure 14 and Figure 10.For this reason, we plot Figure 15 with the major part of Figure 14 and Figure 10.Why illustrate in greater detail as long as control module 1 or signal conditioner 50 just can be realized the supply of direct supply, the transmission and the both-way communication of measured value simultaneously with sensor 6 interconnection below with reference to Figure 15 by two transmission lines.
In Figure 15, the output signal S14 that power supply o controller 120 receives from DAC69 shown in Figure 14, output signal S14 is the signal that is transmitted of high frequency.Controller 120 is controlled, for example according to the output voltage E of S14 signal controlling from variable direct supply Es.Controller 120 for example operational amplifier U2 constitutes.Signal S14 is added to an input end (-).That be added to another input end (+) of amplifier U2 is voltage signal Eo, and it determines the output voltage values E of power supply Es.This voltage signal Eo is equivalent to the signal Eo that is added to terminal T3 among Figure 10.
Variable direct supply Es is made up of triode Q3 and Q4, and their collector links to each other with power Vcc and common potential respectively.The emitter of triode Q3 and Q4 links to each other with a transmission path 91.This power supply Es is equivalent to triode Q1 shown in Figure 10.Power source voltage Vcc shown in Figure 15 is identical with power source voltage Vcc shown in Figure 10.
Sensor 6 sends 4 to 20 milliamperes low-frequency current according to the place measured value.Voltage variation detectors 121 is superimposed to high-frequency signal or modulated signals on the low-frequency current of sensor 6 generations, and gives signal conditioner 50 with the consequential signal loopback, contains the response message 2 to 50 photos and sending messages M1 of signal conditioner in this high-frequency signal.
Resistance R extracts information Iin as voltage signal VR, signal Iin is that this transmission path 91 transmits.This resistance R is equivalent to resistance R shown in Figure 10.
The voltage VR that is obtained by this resistance R is added on low-pass filter 55 and the rate bandpass filter 53.Low-pass filter 55 produces 4 to 20 milliamperes of signal SE, the value that signal SE indication measurement obtains.Bandpass filter 53 produces high frequency component signal SD(Fig. 1).In Figure 15, amplifier and ADC52 that the signal to from resistance R that provides among Fig. 1,8,14 amplifies have been omitted.
With reference now to Figure 16, the course of work of structure shown in Figure 15 is described.Figure 16 (a) provides signal S14 shown in Figure 15.In this example, signal changes on positive and negative two directions.Operational amplifier U2 receives signal S14 and constant voltage signal Eo shown in Figure 16 (a), and controls the output voltage E of variable direct supply Es according to the difference of these two.Like this, the output voltage E that is delivered on the transmission path 91 by power supply Es can change according to high-frequency signal S14, and this signal S14 produces shown in Figure 16 (b) like that, and its voltage amplitude is represented by Vd1.The voltage E that is sent by variable direct supply can be provided by following formula: E=Eo+Vd1(1)
VR＝R·Iin （2）
By equation (1) and (2), can provide the voltage VL that is added on the transmission block 80 that links to each other with two-wire transmission path 91:
VL＝E-VR
＝Eo+Vd1-R Iin （3）
This voltage VL supposes shown in its waveform and Figure 16 (e).Like this, the voltage VL that is added on the transmission block 80 changes with high-frequency signal S14.The voltage variation detectors 121 that comprises in piece 80 detects the variation of voltage VL, and extracts the high-frequency signal S14 from signal regulator 50.So, read information M1, and controlled sensor 6 according to information M1 by this signal S14 indication.The voltage VL that produces on transmission block 80 is very high, if the transmission current Iin that flows through supposition has reached its maximal value, for example 20 milliamperes, just can keep a sufficiently high rated voltage, with operation transmission block 80.
Be sent to the high-frequency modulation signal S20 of signal conditioner by transmission block 80, communication signal in other words changes in positive and negative two directions and to be transmitted electric current I in, for example shown in Figure 16 (c) like that.This high-frequency signal S20 has caused the variation of the voltage VR that sets up on the resistance R.Corresponding to the process control amount, the low frequency signal of sending from transmission block 80 or the signal of indication measurement value by low-pass filter 55, cause signal SE shown in Figure 16 (f), and the signal SE that sends from wave filter 55 gets the analog quantity wave form in the drawings.But in fact signal SE is a digitally encoded signal, each instantaneous amplitude of representative simulation waveform.
The high frequency modulated signals S20 that sends from transmission block 80, or communication signal by bandpass filter 53, extract signal SD shown in Figure 16 (g) there.In Figure 16 (g), the signal SD that receives wave filter 53 generations shows as analog waveform.But in fact it is a digitally encoded signal, each instantaneous amplitude value of representative simulation shape.
In the structure of Figure 15, added resistance R, connect with two-wire transmission path 91, therefore, the supply voltage VL that is added on the transmission block 80 correspondingly reduces.Specifically, be added to voltage VL on the transmission block 80 by formula
VL＝E-Iin·R （4）
Provide.So, be necessary to design an electronic circuit, (for example 20 MAHs also can be kept operate as normal to guarantee reaching its maximal value at transmission current Iin.Structure shown in Figure 17 has solved this problem.In Figure 17, resistance R is connected between the output terminal and input end (-) of amplifier U3.The input end (+) of amplifier U3 links to each other with common potential.In this structure, the input end (-) of amplifier U3 can be considered to common potential or virtual (virtual) earth point.Like this, we have
VL＝E
By topworks 7 being connected in (via two-wire transmission path 95) between terminal P10 and the P1 and do not change the structure of signal conditioner shown in Figure 14, just 4 to 20 milliamperes working control signal can be delivered to topworks 7 from control module 1.Meanwhile, can between control module 1 and topworks 7, realize both-way communication.When the circuit structure of Figure 18 during in work, power unit 92 links to each other with structure shown in Figure 11.In this case, switch SW 3 links to each other with contact a2, so power unit 92 is worked under the constant current output state.
With reference now to Figure 11, the connection of power unit 92 shown in Figure 180 is described.Terminal T3 shown in Figure 11 links to each other with control circuit 94 shown in Figure 180.In this case, be 0 from the signal S17 of control circuit 94, i.e. S17=0.DAC69 shown in Figure 180 is corresponding to the signal output apparatus among Figure 11 115.In other words, only be added to the input end (+) of the amplifier U1 of Figure 11 from the signal S14 of DAC69 among signal output apparatus 115 or Figure 18.
As previously mentioned, this signal S14 is an analog voltage signal, therein, corresponding to the low-frequency voltage signal of 4 to 20 milliamperes of electric currents with represent the modulated high-frequency voltage signal multiple tracks of communication information M1 to combine.Information M1 passes to topworks 7 from control module 1.In Figure 18, communication information M1 results from the signal S8 from control module 1.
Iout＝V14/R
As a result, described in Figure 18, low-frequency current component ia(is arranged corresponding to 4 to 20 milliamperes in the signal that power unit 92 produces) and high-frequency current component ib(corresponding to communication information) superposition together.
Topworks 7 is driven by the low-frequency current component ia of input.Receiving circuit 7a produces modulated signals Vin at terminal P1, and signal Vin contains relevant for response incoming traffic information M1 and information M2.
Modulated signals Vin is sent to input circuit 51.Digital signal processing part 61 extracts representative information M2(and sees Fig. 1 by finishing aforesaid operations) information S1.The signal S5 of representative information M2 is sent to control module 1.
In the structure of Figure 18, the signal Vin that topworks 7 sends only contains communication information, is work so have only wave filter 53 in two wave filters 53 that comprise and 55 in digital processing part 61.
Circuit structure shown in Figure 21 is similar to this part of circuit structure among Fig. 1: it is from the input end P1 of received signal SA, till the output terminal of digital demodulator 54 and digital filter 55.Detuner 54 sends communication information S1.The output of wave filter 55 is signal SE, and it indicates the value that measures.In Fig. 1, it can replace bandpass filter 53(with Hi-pass filter) in parallel with low-pass filter 55.And two wave digital lowpass filters 132 and 133 are series connection in Figure 21.Even use the structure of Figure 21, also can extract low frequency signal SE and high frequency communication information S1 respectively.
Still with reference to Figure 21, input end P1 is corresponding to the input end P1 among Fig. 1.Resistance is connected between input end P1 and the common current by switch 136.This switch 136 is closed and disconnected under control module 1 control of Fig. 1.The signal that provides to this input end P1 is index map 22(a) shown in the low frequency signal ea of measured value and the superposition of high frequency communication signal eb.The frequency range of supposing the frequency component place that comprises among low frequency signal ea among Figure 22 (a) and the communication signal eb is lower than frequency f w shown in Figure 23.
Usually, variable gain amplifier 131 arrives a certain voltage levvl with the voltage amplification of setting up on the resistance R, and for example 1 volt, so that can easily handle by the next stage of electronic circuit.The amplification degree of amplifier 131 is controlled by the control module 1 of Fig. 1.
The output of variable gain amplifier 131 is added on ∑-△ modulator 52, there conversion of signals is become digital form.Modulator 52 is over-sampling analog-digital converters.Because this modulator was done to describe, had just no longer described here in conjunction with Fig. 3.The sampling rate of modulator 52 remains on a given frequency, for example 1 megahertz.Low-pass filter 132 is delivered in the output of modulator 52.
Low-pass filter 132 calculates the moving average of a plurality of (for example 32) the Ser.No. word code that is produced by ∑-△ modulator.Specifically, modulator 52 produces digital code, and its method is 1 or 0, and frequency is 1 megahertz, promptly is spaced apart 1 microsecond.Low-pass filter 132 removes this calculated value with 32 then with the addition of 32 Ser.No. word codes, obtains mean value.Each input code signal is repeated this a series of computings.Like this, just, calculate the moving average of digital code.
The low-pass filter 132 of working by this way shows attenuation characteristic 140 shown in Figure 23.Output signal (being designated as S30) from wave filter 132 is a digitally encoded signal (Figure 22 (b)), contains the low frequency signal ea and the high frequency communication signal eb of indication measurement value.
The value of the corner frequency fw of filter characteristic 140 shown in Figure 23 can change, and the practice is to replace above-mentioned value " 32 " with different values.Can carry out this modification according to signal from control module 1.Control module 1 can become such value (for example 32) to turning frequency configuration, makes its high-frequency signal eb that delivers to terminal P1 not be low pass filtering device 132 and cuts away.
The output data that low-pass filter in back 133 receives from previous low-pass filter 132 is calculated the moving average from for example 8 Ser.No. word codes of a low-pass filter 132 of computing.Specifically, a back wave filter 133 will from 256 of ∑-△ modulator 52 (summation of 32 * 8=256) Ser.No. word codes and with 256 except that this calculated value.In other words, a back wave filter 133 is got the moving average of 256 digital codes, so this wave filter only extracts those signals that its frequency is lower than the frequency of low-pass filter 132 signal that extracts.
The operation of this back low-pass filter 133 as described previously, its attenuation characteristic (4) as shown in figure 23, its corner frequency is represented by fu.In other words, the output signal SE of a back wave filter 133 is digitally encoded signals shown in Figure 22 (c), and it does not comprise high-frequency signal eb, and only comprises the low frequency signal ea that represents measured value.The characteristic of this back wave filter 133 also can be by control module 1 correct easily, and its practice as hereinbefore.As a result, the low frequency component of a back low-pass filter 133 generations is to be added to those low frequency components (or the signal of expression measured value that is comprised among the signal SA of input end P1; For example, 4 to 20 milliamperes electric current).
Equally, obtain high fdrequency component or communication information by digital comparator 134 and digital demodulator 135.Digital comparator 134 is compared signal S30 shown in Figure 22 (b) with signal SE shown in Figure 22 (c).Comparer 134 produces signal S31, and when signal S30 passed signal SE, the code value of signal S31 just sent variation.Signal S31 indicates the cycle of signal eb shown in Figure 22 (b).Digital demodulator 135 can detect the frequency of posting high-frequency signal eb, that is to say can access communication information according to periodic solution, S1.
Two low-pass filter series connection in the circuit structure shown in Figure 21, produce following benefit: a wave digital lowpass filter is simpler than digital band-pass filter and digital high-pass filter on hardware configuration, can constitute with the circuit block that lacks than back two kinds of wave filter quantity.In other words, structure shown in Figure 21 makes this novel signal regulator easily make the integrated circuit form.By this way, high frequency communication information S1 is taken out from detuner 135, and will represent that the low frequency signal SE of measured value takes out from a back low-pass filter 133.
By top description, can find out that the present invention has following advantage:
(1) as long as a few signal conditioner of preparation or a few hardware just might be adapted to multiple sensors and multiple topworks.
Describe this point now in detail.By input circuit 51, the conversion of signals that sensor or sensitive element are provided becomes to surpass the voltage signal of one level.This voltage signal is all converted to digital form by ADC52.So, obtained and the corresponding digital signal of the output signal of sensor or sensitive element by ADC52, no matter and be that any sensor or sensitive element link to each other with this signal conditioner.Like this, the information and the communication information that comprise 3 indication measurement values in the digital signal by the ADC52 generation.The digital signal that the digital signal processing part 61 and the 70 couples of ADC52 provide is carried out digital arithmetical operation, thereby extracts measured value and communication information, and these arithmetical operations can be adapted to connect the kind of sensor.Content by digital signal processing part 61 and the 70 digital arithmetical operations of being finished can be changed by software.
Briefly, according to the present invention, the output of each sensor or sensing unit has all converted digital form to.Then to the digital signal that produces be applicable to connect the digital arithmetical operation of sensor or sensitive element type.Like this, just, extracted and measured resulting value and communication information.Because the content of digital arithmetical operation can be revised by software, therefore, the signal conditioner of being invented can be adapted to various sensor and topworks with its a few.
So far, the applicant has had multiple signal conditioner.According to the present invention, they all can be replaced by a kind of hardware only.Therefore, the present invention has very big superiority.
(2) though connect sensor or topworks has or not communication function, signal can both be by suitably transmitting and receiving.
(3) analog signal processing of equipment part can be with digital signal processing part 61 of the present invention and 70 replacements in the past.Digital signal processing part 61,70, ADC52 and DAC69 are digital circuit, are suitable for easily making the integrated circuit form.This makes the signal conditioner can miniaturization.
When replacing ADC52 shown in Figure 1 with over-sampling a/d C and replacing DAC69, be easier to make these parts with the integrated circuit form with oversampling DAC.An analog to digital converter (ADC) needs to be equipped with the noise on noise that prefilter 81 is avoided sampling and caused.This wave filter 81 is by making such as analog elements such as capacitors.So even ADC makes the integrated circuit form, the large volume of this analog pre-filter 81 is still a problem.Yet in this sampling system, signal is with quite high speed sampling, so can make with little electric capacity and like.In other words, over-sampled converter is suitable for being included in the integrated circuit.
(4) in this new equipment, receiving circuit part and transfer circuit part are all carried out digital arithmetical operation to obtain desired signal to input signal.Therefore, if inputed or outputed condition changing, can revise the content of these digital arithmetical operations by software.Thereby make new equipment can be adapted to the change of condition rapidly.
(5) in Figure 14 and circuit shown in Figure 15, by with 6 of control circuit 1 or signal conditioner 50 and sensors with the pairs of transmission line interconnection, can realize simultaneously that just direct current supply, measured value transmit and both-way communication.
Claims (8)
1, a kind of signal conditioner that links to each other with sensor by transmission path transmits signal reposefully between this signal conditioner and the control module, described signal conditioner comprises:
Electric supply installation provides direct supply by transmission path to sensor;
Input circuit receives from signal of sensor, and it is transformed into analog voltage signal above preset level;
Analog-digital commutator, the analog voltage signal that input circuit is produced converts digital signal to;
First digital filter extracts the low speed signal component from digital signal;
Second digital filter extracts the high speed signal component from digital signal;
Measure portion is carried out digital processing to the low speed signal component that is extracted, to obtain measured value;
Demodulating equipment carries out digital processing to the high speed signal component that is extracted, to obtain communication information.
2, according to the signal conditioner of claim 1, wherein said transmission channel is made of two transmission lines.
3, according to the signal conditioner of claim 3, wherein said power unit comprises:
Stabilizator, it can be operated in current constant mode or constant voltage mode, should stable provide steady current to the exterior terminal that links to each other with one of described pairs of transmission line under current constant mode, and this stabilizator provides constant voltage to exterior terminal under the constant voltage mode; And
The mode switching device shifter, it switches the working method of stabilizator according to the kind of the sensor that links to each other with exterior terminal between constant mode and current constant mode.
4, a kind of signal conditioner that links to each other with sensor by two transmission lines, this regulator allow signal to transmit reposefully between sensor and control module, and described signal conditioner comprises:
Electric supply installation, it provides DC voltage by two transmission lines to sensor, and can change this DC voltage to the high-frequency signal of the communication information of sensor transmission according to containing by control module;
Input circuit, it receives from signal of sensor, and converts it to above preset level analog voltage signal;
Analog-digital commutator is used for converting the analog voltage signal that input circuit produces to digital signal;
First digital filter is used for extracting the low speed signal component from described digital signal;
Second digital filter is used for extracting the high speed signal component from described digital signal;
Measurement mechanism is used for the low speed signal that is extracted is carried out digital processing.Measure resulting value to obtain; And
Demodulating equipment is used for the high speed signal component that is extracted is carried out digital processing, to obtain the communication information that sensor transmits to control module.
5, by the signal conditioner that transmission path links to each other with sensor, this signal conditioner allows to transmit signal reposefully between sensor and control module, and described signal conditioner comprises:
Digital modulation device, it receives expression from first digital signal of control module to the communication information of topworks's transmission, and produces second digital signal, and this second digital signal is corresponding to each instantaneous value of the modulated signals amplitude of expression communication information;
Totalizer, it produces three digital signal and the described second digital signal sum, and this three digital signal is corresponding to the in check degree of topworks;
Digiverter receives the output signal from totalizer, and converts thereof into simulating signal;
Output circuit receives the analog output signal from described digiverter, amplifies this simulating signal, and amplifying signal is delivered to topworks.
6, according to the signal conditioner of claim 5, wherein said transmission path is made of pairs of transmission line.
7, according to the signal conditioner of claim 6, wherein said output circuit comprises:
Stabilizator, it can be operated in current constant mode or constant voltage mode, and this stabilizator provides steady current to the exterior terminal that links to each other with one of described pairs of transmission line under current constant mode, and this stabilizator provides constant voltage to exterior terminal under the constant voltage mode; And
The mode switching device shifter, it switches the working method of stabilizator according to the kind of the topworks that links to each other with exterior terminal between constant voltage mode and current constant mode.
8, a kind of signal conditioner that links to each other with topworks by two transmission lines, this signal conditioner allow signal to transmit reposefully between topworks and control module, and described signal conditioner comprises:
Electric supply installation, it provides a DC current by these two transmission lines to topworks, and can change this DC current to the high-frequency signal of the communication information of topworks's transmission according to containing by control module;
Input circuit, it receives the signal from topworks, and converts thereof into the simulating signal above certain level;
Analog-digital commutator, it will become digital signal from the analog signal conversion of input circuit;
Digital filter, it extracts the high speed signal component from described digital signal;
Demodulating equipment is used for the high speed signal component that is extracted is carried out digital processing, to obtain the communication information that transmits to control module from topworks.
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP334399/90 | 1990-11-30 | ||
| JP33439990A JP2734200B2 (en) | 1990-11-30 | 1990-11-30 | Signal conditioner |
| JP48352/91 | 1991-03-13 | ||
| JP49851/91 | 1991-03-14 | ||
| JP49850/91 | 1991-03-14 | ||
| JP03049851A JP3139502B2 (en) | 1991-03-14 | 1991-03-14 | Analog / digital communication method and apparatus |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1064166A true CN1064166A (en) | 1992-09-02 |
| CN1028808C CN1028808C (en) | 1995-06-07 |
Family
ID=26390297
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 91111200 Expired - Fee Related CN1028808C (en) | 1990-11-30 | 1991-11-29 | Signal conditioner |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1028808C (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8089386B2 (en) | 2006-08-04 | 2012-01-03 | Endress + Hauser Wetzer Gmbh + Co. Kg | Isolation unit for a conventional 2-conductor communication connection including a sensor, a measurement transmitter and a control unit |
| CN106982060A (en) * | 2016-01-18 | 2017-07-25 | 特变电工新疆新能源股份有限公司 | A kind of analog collection system |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6135940B2 (en) * | 2014-11-12 | 2017-05-31 | 横河電機株式会社 | I / O module |
-
1991
- 1991-11-29 CN CN 91111200 patent/CN1028808C/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8089386B2 (en) | 2006-08-04 | 2012-01-03 | Endress + Hauser Wetzer Gmbh + Co. Kg | Isolation unit for a conventional 2-conductor communication connection including a sensor, a measurement transmitter and a control unit |
| CN106982060A (en) * | 2016-01-18 | 2017-07-25 | 特变电工新疆新能源股份有限公司 | A kind of analog collection system |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1028808C (en) | 1995-06-07 |
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