CN1006829B - Programmable logic controller system for hazardous environment - Google Patents

Abstract

A programmable logic controller system for use in a hazardous environment has a microprocessor-based logic controller (10) and also a unit (30) incorporating a microprocessor and an alterable memory such as a RAM. This unit can be coupled directly or indirectly to the controller for testing and modification of a program. After testing the program is transferred to a non-volatile memory outside the hazardous environment. This non-volatile memory is then taken into the hazardous environment and fitted to the controller for routine operation. This allows a program to be tested on the controller before it is committed to the non-volatile memory. Communication between the unit, any intermediate item of equipment and the controller is preferably through opto-isolators to preserve electrical isolation. Serial data transmission is preferred.

Description

Programmable logic controller system for hazardous environment

The present invention relates to a kind of programmable logic controller (PLC), for example, be applicable to the programmable logic controller (PLC) of industrial premises.At present, general Programmable Logic Controller is known already.Yet the present invention proposes a kind of hazardous environment that is applicable to, the programmable logic controller system of explosive hazard environment is for example arranged.

The present invention proposes a kind of system that connects some unit, and this system comprises:

(1) first module that is applicable to the controller of hazardous environment, it comprises that one is stored programmed control, and the microprocessor of nonvolatile memory of this program of storage can be housed.

(2) Unit second that comprise variable type memory, it allows to change selectively the data that exist in each storage address under the situation of the full content of not removing this memory.

Above-mentioned controller and above-mentioned second unit design get and can be connected to each other, and above-mentioned at least controller is to be placed in the hazardous environment, and the program that this controller is stored in by (at least when initial) in the variable type memory of above-mentioned Unit second is controlled.Then, program is sent to the nonvolatile memory that is contained on the controller.

The present invention can pack in the program that is verified and be installed in before non-volatile memory on the controller carries out routine operation, allow user's check just on the controller and the program of under hazardous environment, using, and before check, do not need earlier program to be write nonvolatile memory.Advantage of the present invention is to allow user's modification and check the program of just working again in hazardous environment.

Before the microprocessor operation of controller, the program of storing in the variable type memory of above-mentioned Unit second can copy in the volatibility memory of controller.This controller can be adorned a nonvolatile memory, also can adorn a volatibility memory (program copies to this memory from Unit second).

Be equipped with the keyboard that energy is used at hazardous environment preferably for controller and/or above-mentioned Unit second, so that revise the program in the variable type memory of above-mentioned Unit second.

Unit second is the portable unit that suitable hazardous environment uses preferably, no matter whether it is of portable form, Unit second preferably includes a microprocessor.

Portable Unit second and being connected of controller can be with (or with cable this portable unit is connected with the direct of this controller, this control this moment is as all being placed in the hazardous environment with portable unit by electrical cnnector.

The another kind of connection is by being also placed in the connection of a middle device in the hazardous environment.At this moment this middle device can be used for the operation of supervisory control device and/or the supervisory control device factory under operating, and this monitoring unit can be placed on the place away from controller.

What also have a kind of connection may be the connection that extends to hazardous environment inside from the outside of hazardous environment.If when Unit second can not be portable, this connected mode often was used.

" variable type memory " includes the volatibility memory, and it preferably has the random access memory (RAM) (RAM) of standby power supply, with anti-lost storage content.

When to the satisfaction of the program in the modifiable memory, it can be transferred to a nonvolatile memory, then this nonvolatile memory is contained on the controller, control above-mentioned controller with this program.The process that sends nonvolatile memory to is carried out beyond hazardous environment usually.

Non-volatile memory is semiconductor memory normally, just can preserve the storage content under without any the situation of power supply, and this memory can be such as programable read only memory (EPROM), if do not wipe the full content of memory, its content can not disappear.

The example that can replace EPROM is to rewrite read-only memory EAROM, and this read-only memory can change single memory address, but the speed of rewriting is slower than the speed of reading a memory address or write among the RAM.

Usually, controller can not change the content of nonvolatile memory.

Better is that this system is included in outside the hazardous environment program is sent to the device that nonvolatile memory is used from portable unit.This device preferably or comprise an EPROM programmer (also being the EPROM solidification device sometimes).

In order to give the EPROM convey program, preferably portable unit directly is connected with EPROM programmer.This EPROM programmer also can be used for duplicating the program among the EPROM, with version as backup, it can also carry out other function, for example provide output information to printer, so that the hard copy of production process table, or this program copied to other peripherals by industry standard interface or principal computer gets on.

Better is, portable unit has battery supply, and controller is connected by one or more optoisolators with portable unit, to keep electric insulation.

Another advantage is, portable Unit second is a matching unit, and it comprises a keyboard, a display and a microprocessor, no matter whether portable unit is connected with controller, it can both load or change memory.

In preferred the arrangement, controller and Unit second be arrange like this and operation (as above summary) a program from the variable memory of above-mentioned Unit second is sent to RAM the controller.After this, the microprocessor of controller just moves under the control of this program that is transmitted.

Preferably program is sent to controller from Unit second with such speed, promptly the clock speed of normal operation (at microprocessor and deposit between the memory of microprocessor executive routine the speed during direct communication) is wanted slow speed (must be accompanied by low frequency) transmission with than the microprocessor direct access memory of controller the time.The pulse that transmits is probably than longer with the pulse of normal clock speed direct access.

This transmission at a slow speed can be by being formed with the transmission of a kind of pulsed frequency also low frequency of clock frequency of the microprocessor in controller and the Unit second (promptly than).This transmission can realize by signal exchange between two unit, but often really not so.It also can be serial transmission.

Transmit at a slow speed and can realize that more wide region is chosen optoisolator,, between the conductor of two circuit, just can provide bigger physical space, also just realized isolation owing to chosen the wide ranges of optoisolator.

In order further to explain the present invention, now in conjunction with following description of drawings several embodiments of the present invention by example:

Fig. 1 illustrates the various piece of system,

Fig. 2 and Fig. 3 illustrate a part of circuit of distinguishing slightly system.

With reference to accompanying drawing 1, programmable logic controller (PLC) 10 is installed among a kind of hazardous environment (may be the colliery) earlier.

According to a kind of requirement of explosive area, controller has been equipped with multichannel input and Duo road Shu Chu Armor dress cable connector (for example, 12,14).

This controller has considerable I/O (I/O) passage, and is equipped with some interchangeable circuit boards, so that these passages and input and output attachment unit interface, these circuit boards have three types, and a kind of circuit board is 16 tunnel inputs and I/O channel interface.Other two kinds of circuit boards all are with controller and output channel sensor interface, and wherein a kind of circuit board provides direct drive for 16 tunnel outputs under the order of the microprocessor of controller.And another kind of circuit board under the situation of band output load condition monitoring, provides direct drive for 8 tunnel outputs under the order of the microprocessor of controller again.

This controller is by the power supply unit 16a power supply that is applicable to the explosive area, and this unit also is the circuit board power supply of the input interface of the sensor.Yet each output circuit plate also needs one or two additional supply unit, and each 16 channel circuit board has two to be the circuit of 8 passage services, and each 8 channel circuit board has two to be the circuit of 4 passage services.These circuit are isolated mutually on electric, also isolate each circuit design Cheng Youyi independently power supply unit 16b power supply with other circuit of controller.Use many power supply units and be electrically isolated from one another, satisfied the requirement in explosive area.The input signal of the output driving circuit that these electricity are isolated transmits through optoisolator.

A microprocessor (CPU), a nonvolatile memory permanent installation, that deposit its operating system and a permanent installation are arranged in controller, to when program run, be used as a temporary memory and for example deposit some variablees, and be used as a storage stack.In addition, controller also comprises one for connecting the connector 20 of detachable circuit board 22 usefulness.

In order to use selectively, two kinds of circuit boards are provided.A kind of circuit board 22a has RAM23, it can be the non-volatile memory of EPROM43 that another kind of circuit board 22b has one at least, no matter the sort of circuit board of packing into, this memory in the storage conversion of controller microprocessor, occupy same space, circuit board 22a and 22b preferably identical or similar as far as possible.

There are a keyboard 32, liquid crystal (LCD) display 34, an inner microprocessor (CPU), a non-volatile memory and a RAM35 who has watchdog routine in portable second unit 30.Nickel-cadmium battery 36 power supplies that this unit can be charged repeatedly by an independent charger 37.Thereby this unit is from supporting, the user of this system control program of a plan by controller 10 operations of can packing into.The user can use the keyboard 32 of portable unit, pack into the RAM35 of portable unit of this control program.Then, the user is by keyboard 32 input commands, with display 34 scrutiny programs.This portable unit 30 also has one or more port 38, can be connected with the many peripherals that comprise EPROM programmer 42, and so just can pack program into is installed among the EPROM on the circuit board 22b.

Such as EPROM formatter 42 and battery charger 37 such peripherals is not enter the explosive area.

Portable unit 30 will be put into the explosive area, links to each other with controller 10 by port 39, and these two unit are to arrange like this, promptly when needs connect, add connection by the light isolation, when carrying out data transmission, optoisolator makes electrical isolation between these two unit.Optoisolator both can be placed in the controller, also can be placed in the portable unit, and dual mode is all desirable.

The selective light isolator promptly realize separation physically between two circuit, and this separation is enough to satisfy the technical manual of using in the explosive area like this.

When unit 10,30 connects in the explosive area, order of available keyboard 32 inputs, start a program (it is kept among the RAM35 of portable unit and is copied among the RAM23 on the controller circuit board 22a), then, this program is carried out by the microprocessor of controller.

Usage is as follows:

Designated program is packed among the RAM35 by keyboard or other peripherals such as EPROM programmer.Then portable unit 30 is brought into the explosive area, the circuit board 22a of RAM has been installed and has loaded onto at explosive area middle controller 10, in the RAM23 of this program copy to the circuit board 22a, check this designated program then, promptly moving this program by controller checks, though in this stage, the controller function system also allows by the direct input command of the keyboard of portable unit.

At test period, can revise the program among the RAM35.At the scene, if necessary, can be in RAM23, to test the program copy of having revised.When program has arrived final version, unit 30 is taken out from the explosive area, receive on the EPROM programmer 42, this program copy to EPROM43.EPROM43 is contained in after circuit board 22b goes up, and brings the explosive area again in order to replace circuit board 22a, so just the final version of user's program as director demon, this program is kept among the EPROM of circuit board 22b.

Should pay attention to providing the change of program, to increase the dirigibility that this system uses at the scene, explosive area.Can also increase the matching performance of this portable unit 30 like this.

The program of controller 10 and portable unit 30 and their operating system is design like this, promptly any one microprocessor all can not be from the memory of another unit direct access.Apparently, is a kind of very suitable technology by the interface between two unit to the direct access of memory, yet, we have found that and to avoid this technology of using, what be designed to utilizes the method for serial data transmission to the program among the RAM35 with said units, copies in the memory of controller to go.Utilize slower transfer rate to allow use optoisolator at a slow speed, making has bigger actual isolation between the circuit.

RAM35 is preferably cmos type, because this RAM is low in energy consumption.CMOS type RAM is also preferably adopted in other places in system.In fact, because the cause of low-power consumption comprises that all chips of microprocessor all are cmos type.

Portable unit 30 as shown in the figure, and two independently port 38 and one ports 39 are independently arranged, and port is the least possible, might be only with a port with three port functions.

Portable unit 30 can have a slice and RAM35 to divide the RAM chip of opening to be used for depositing some variablees and be used as a storehouse.In other words, this usefulness is done in the address of some in RAM35.

Interchangeable circuit board 22a, 22b except interchangeable RAM and non-volatile memory are housed, preferably lack dress and even do not adorn parts.; can load onto additional parts easily on it; on two circuit boards as spare unit; reducing the sum of the circuit board that controller needs, then these circuit boards can have the operating system program that deposits controller in, address decoding logic ROM and (or) chip of microprocessor.

In the development phase, exist program among the RAM35 can consider to comprise to realize single-step operation, at the left alone without help machine of the point of interruption of some appointments, or other diagnostic functions, these functions disappeared before copying to EPROM immediately.Circuit board 22a can consider to have the hardware that single-step operation is used, but circuit board 22b does not need this function, can save.

Fig. 2 is the same with above-described system except circuit board 22a, the 22b that exchanges do not utilize with system shown in Figure 3.The substitute is RAM23 or non-volatile memory such as EPROM43 are contained on province's force socket of controller.

Fig. 2 illustrates a part of circuit of controller.Another part circuit (connection of the memory of for example time clock generation, conversion input and output) can be used the architecture of microprocessor of conventional microcontroller.

As shown in Figure 2, for example controller 10 comprises that the microprocessor 50 that is connected with address bus A with data bus D removes outside three topmost address wires 51,52 and 53, and other each bar line does not illustrate in the bus.As shown in the figure data bus and address bus and the operating system of depositing this microprocessor be watchdog routine ROM54, as working storage deposit some variablees and storehouse RAM55, be used for laying RAM chip 23 or non-volatile memory such as EPROM chip 43 labour-saving sockets 56 are connected, article two, topmost address wire 52,53 link to each other with 2/4 coding chip 58, this chip also links to each other with the sheet of ROM54 and RAM55 choosing (CS) pin, and this chip also links to each other with that terminals of " accepting chip selection (CS) pin line of RAM23 or non-volatile memory 43 " on the socket 56.

Decoding scheme is contained in ROM54, three 1/4 continuous microprocessor memory conversion fractions in memory chip in the socket 56 and the temporary ram memory 55, and remaining 1/4 be used for the memory conversion of I/O.

Those terminals that (RD) control line is connected to " accepting the permission output pin line of RAM23 or EPROM43 " on exportable (the OE)/pin of permission output of RAM chip 55 and the socket 56 of reading from microprocessor.

In order to make socket can accept RAM23 chip or EPOM chip 43, this circuit should be designed to its RAM and have the various functions of being implemented by identical pin, the circuit of all kinds chip with EPROM.Usually the EPROM and the RAM chip of commercial identical memory capacity all have a lot of function (as: data line, address wire and chip are selected), and implement its function on corresponding pin.

With regard to pin, be that different, socket 56 line end correspondingly can come wiring by interlock selector switch 60 for the pin function of RAM and EPROM.

In an example shown, when switch during at lower position, pin 61 links to each other with (WR) control line of writing of microprocessor.When switch during in the high position, it links to each other with address wire 51.This just can be applicable to RAM and EPROM respectively.

Correspondingly, another pin 62 links to each other with address wire 51 or power source voltage Vcc.

Though the wiring of not drawing socket 56, but several terminals also can be used for making the memory of socket acceptance more than a kind of memory capacity by the on line principle of selector switch, as 8 8K and 8 32K, two kinds all can be utilized in each case, and most pins have the memory of dual inline type (DIL) encapsulation of 28 pin of identical function.

The example of suitable commercial memory chip can adopt the EPROM chip of 27C64 and 27C256 and 6264 and 65256 RAM chip.

RAM55 has a rechargeable standby power supply (not illustrating), so that preserve the content of its storage when power supply breaks down, primary power cource charges to standby power supply automatically by a diode, in order to keep very limited stand-by power supply.When breaking down, do not select primary power cource RAM55 for use.This will be selected to guarantee that when impact damper was powered by standby power supply, " starting " pin of impact damper linked to each other with the primary power cource voltage vcc between the pin by a chip that is inserted in code translator 58 and RAM55.If primary power cource breaks down, then impact damper is not just worked, and its output becomes high impedance, and passes through resistance 65 with backup power source voltage V _BUAdd.

Fig. 3 illustrates the employed circuit of portable unit, the same with controller, portable unit 30 has a microprocessor 70, and only three topmost address wires is shown separately and label is 71,72,73 in Fig. 3 by the ROM74 that data bus D, address bus A and 71,72,73 are connected to the deposit operation system.Data bus also links to each other with RAM76 with address bus, and the part of RAM76 is as working storage, and its another part is as the storage user program.2/4 line code translator 78 links to each other with chip select pin, and microprocessor 70 can alternately be selected rom memory 74 and RAM76, therefore, and two 1/4 continuous memory conversion fractions of pack into ROM74 and RAM76 microprocessor 70.

Portable unit has a keyboard 32 and a display 34 not to express in Fig. 3.They are connected with the input/output end port of microprocessor 70.If yet employed microprocessor does not have such input/output end port, keyboard will link to each other with microprocessor by a general Peripheral Interface adapter with display.

Fig. 2 and Fig. 3 also show the method that is connected between this portable unit and the controller.

Microprocessor 50,70 all has the pin that is used for the serial data input and output (the serial data input and output of other little processing can link to each other with microprocessor by, independently universal asynchronous receiver/transmitter (UART) UART provides).

This portable unit comprises a pair of optoisolator 80,82.The serial data output terminal 84 of microprocessor 70 links to each other with the diode of isolator 80, and the transistor AND gate serial input terminal 86 of isolator 82 links to each other.

The transistor of the diode of isolator 82 and isolator 80 by 4 pins of a socket 90 to the controller 10 weak point and the jumper cable of flexible is connected on 4 pins of socket 88, socket 90 is connected to the power supply of controller and the serial data input and output pin of microprocessor 50, when connecting by jumper cable with convenient socket 88,90, the serial output terminal 94 of microprocessor 50 links to each other with the serial input terminal 86 of microprocessor 70 by isolator 80, and serial output terminal 84 links to each other with the input end 96 of microprocessor 50 by isolator 82 simultaneously.

Arrangement can make between portable unit 30 and the controller 10 without any under the condition that is connected on directly electric like this, carries out serial data transmission and signal exchange between two microprocessor.

Being connected of " advancing " of input end and output terminal 84,86,94,96 and " going out " all will be by amplifying impact damper 98.The pin of socket 88 and socket 90 respective pin are represented with label 1,2,4,5.

Serial data transmission speed is per second 500 bits or lower, and the clock frequency of microprocessor can be 1 megahertz or higher.Therefore, the pulse of each on serial link is sustainable connects hundred clock period.

Microprocessor 50 has a pin one 00 of linking the input/output end port of switch 102, and switch 102 can be controlled pin 100 and connect power source voltage Vcc or ground connection.

It is in order to put controller 10 in " free running mode " or " debud mode " that this switch is set.During energized, operating system begins initialization, then, and test pin 100 and corresponding each branch.If switch 102 places " free running mode ", microprocessor is then carried out any program in the memory that is contained on the socket 56.If switch 102 places " debud mode ", operating system is then waited for from portable unit 30 and being sent, by an order of serial link transmission.

Fig. 2 is very similar to the system that Fig. 1 is adopted with the system that Fig. 3 is adopted.

After a program was packed into by the keyboard of portable unit, this unit just was connected on the controller 10.Socket 56 planted agents at this stage controller are equipped with RAM chip 23, and switch 102 should place " debud mode ", and this program is from RAM76 copies to RAM23 the socket 54.The instruction of finishing this program should be put into the operating system of two microprocessor 50,70, and finishing above-mentioned order of duplicating is to import by the keyboard of portable unit, and by serial data link transmission between portable unit and the controller.Next step is to identify designated program.If desired, the program among the RAM76 of portable unit can change, and version replication is after changing gone up and tested to RAM23.This can repeat.When testing under " debud mode ", order can be imported by the keyboard of portable unit, and is transferred to controller through serial link.For example, may send the procedure operation of an order according to single-step operation, or begin operation at a certain specified point of program, the order that carry out such program should be placed in the operating system of microprocessor 50.

When program when being satisfactory, portable unit is then disconnected, and is with EPROM programmer 42.EPROM programmer 42 is to be used for program copy to EPROM43.In order to transmit the serial data in the EPROM programmer, the connection of EPROM programmer 42 can realize by programmable device and being connected of socket 88.

EPROM43 after the curing is installed into controller 10, and is contained in the socket 56, to replace RAM23.In the memory conversion of microprocessor 50, EPROM43 occupies identical space with RAM23.

Use because the part of RAM76 is used as " temporary memory ", the program of being packed into by the user this RAM that can not pack into is unless the capacity of can not pack into RAM23 or EPROM43 RAM76 is much larger than RAM23 or EPROM43.In fact this is not a kind of strict restriction.

Claims (10)

1, hazardous environment can connect the system of a plurality of unit down, and it comprises:

(1) first module, this unit is a controller, contains a microprocessor that is stored program management, and has the measure that acceptance has the non-volatile memory of this program; With

(2) Unit second, this unit contain a variable type memory, and it allows under the data conditions of not removing other address, change the data that are retained in each storage address selectively,

This controller and above-mentioned Unit second can link together in hazardous environment, so that the program that this controller is subjected to being stored in the variable type memory of above-mentioned Unit second is managed;

Be at least a keyboard that is provided in the hazardous environment in above-mentioned controller and the above-mentioned Unit second, be stored in the program in the variable type memory of Unit second with modification;

(3) Unit the 3rd, this unit leaves above-mentioned first module at least, in order to the program from the variable type memory of above-mentioned Unit second is sent to the non-volatile memory that is received by this controller,

It is characterized in that:

(a) this controller and above-mentioned Unit second are can link together by a port in hazardous environment, allow to intercom mutually, isolation on mutual simultaneously maintenance is electric, this controller is managed by the program in the variable type memory that is stored in above-mentioned Unit second;

(b) one that is at least in above-mentioned controller and the above-mentioned Unit second provides a keyboard that is used for hazardous environment, is stored in the program in the variable type memory of Unit second with modification; With

(c) above-mentioned Unit the 3rd is positioned at outside the described hazardous environment, and when above-mentioned first module and Unit second were in this hazardous environment, it is convey program between the two effectively.

2, system according to claim 1 is characterized in that Unit the 3rd is an EPROM programmer.

3, system according to claim 1 and 2 is characterized in that it also comprises two or more power supply units that are arranged in hazardous environment, and a unit is the controller power supply, and at least one unit is the output board power supply of this controller.

4,, it is characterized in that Unit second includes a microprocessor according to the system of any proposition in the aforesaid claim.

5, according to any the described system in the aforesaid claim, it is characterized in that above-mentioned Unit second is a matching unit of can be portable, carrying keyboard and display and microprocessor, but can on-load or have and be not connected to the above-mentioned memory of changing this portable unit under the situation of controller at this portable unit.

6, system according to claim 5, but it is characterized in that portable unit has battery supply, but between controller and portable unit, connect by one or more optoisolators, but so that this controller and should on electric, keeping isolating by portable unit.

7, system according to claim 1, controlled operation, when controller is positioned at hazardous environment at least, the program that is stored in the variable type memory of Unit second is sent among the RAM of controller, this controller is subjected to be sent to the control of the said procedure among the above-mentioned RAM of controller then, perhaps be subjected to a programmed control among the above-mentioned RAM in addition, perhaps before above-mentioned memory is contained in the controller, be subjected to be sent to a programmed control of above-mentioned nonvolatile memory.

8, system according to claim 7, it is characterized in that sending program to above-mentioned RAM by one or more optoisolators in being connected between controller and the above-mentioned Unit second with such speed, this speed than at microprocessor and the frequency when depositing direct communication between the memory of the program that this microprocessor carrying out low.

9,, it is characterized in that this controller arranges to such an extent that have above-mentioned RAM or above-mentioned non-volatile memory selectively according to claim 7 or 8 described systems.

10,, it is characterized in that when above-mentioned Unit second and this controller link together the communication between the two is to adopt serial data transmission according to any the described system in the aforesaid claim.

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