CN102855211B - Universal serial bus-balanced voltage digital interface converter - Google Patents
Universal serial bus-balanced voltage digital interface converter Download PDFInfo
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- CN102855211B CN102855211B CN201210353215.2A CN201210353215A CN102855211B CN 102855211 B CN102855211 B CN 102855211B CN 201210353215 A CN201210353215 A CN 201210353215A CN 102855211 B CN102855211 B CN 102855211B
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Abstract
The invention provides a universal serial bus-balanced voltage digital interface converter. The universal serial bus-balanced voltage digital interface converter comprises a USB interface unit, a USB-serial signal converting unit, an RS-422 signal processing unit, an RS-422 interface and a signal isolating unit. The signal isolating unit is arranged between the USB-serial signal converting unit and the RS-422 signal processing unit and used for electrically isolating a signal between the USB-serial signal converting unit and the RS-422 signal processing unit. By means of the technical isolation scheme, compared with the prior art and on the premise that a normal communication function and the signal transmission quality are guaranteed, the electrical connection between a computer and a programmable logic controller (PLC) on a signal transmission line is switched off, and accordingly the stoppage that a communication chip is burned down due to electricity leakage is completely eradicated.
Description
Technical field
The present invention relates to signal isolation field, relate to a kind of USB (universal serial bus)-balanced voltage digital interface converter in particular.
Background technology
PLC (Programmable Logic Controller, programmable logic controller (PLC)) is a kind of widely used industrial automation control appliance.It can process the signal of input PLC, sends according to the program be stored in wherein the operation that corresponding output signal carrys out opertaing device.Because its program can be worked out by user completely, so PLC has extremely strong dirigibility, no matter be thus in single plane automation, or the robotization of whole production line, and even the production automation of whole factory, PLC carries important effect, and by a large amount of practice.
The most important characteristic of PLC can be programmed by user, PLC product now, all that above using PC (PC), special software programs, then by an interface, PC and PLC are connected, and carry out the communication between PC and PLC by above-mentioned interface, i.e. convey program and data, and the state of monitoring PLC.PLC end has been used for the interface normally balanced voltage digital interface (Balanced Voltage Digital Interface) of this task, because it meets ANSI/TIA/EIA-422-B standard, is also called RS-422.Due to common PC not all being equipped with this interface, outfit USB (Universal Serial Bus, USB (universal serial bus)) is therefore usually needed to be connected PC and PLC with the converter of RS-422.
There are many common USBRS-422 converters in the market, adopt a chips (such as PL2303, CP2102, FT232 etc.) as the conversion of communication format, be aided with a small amount of peripheral components, realize the most basic communication function.
In existing generic USB RS-422 converter, USB end (usb interface unit) is held with RS-422 between (RS-422 interface unit) and is connected by USB-serial signal converting unit and RS-422 signal processing unit, concrete, turn serial port chip by a USB to be directly connected with a RS-422 transceiving chip, directly be connected with RS-422 transceiving chip because USB turns serial port chip, have path electrically to exist, so work as in USB or RS-422 one end because static discharge, there is electric leakage in short circuit or other reason, during the situations such as electric voltage exception, semiconductor electronic part will breakdown conducting, current path is formed between two ends, the electronic component on path will be burnt like this in very short time, this is wherein especially fragile with the communication chip in PLC, the most damaged, once PLC damages, PLC will be caused cannot to communicate with PC.
Summary of the invention
In view of this, the invention provides a kind of USB (universal serial bus)-balanced voltage digital interface converter, in order to solve the easily breakdown problem of communication chip in prior art in PLC.
For achieving the above object, the invention provides following technical scheme:
A kind of USB (universal serial bus)-balanced voltage digital interface converter, comprise usb interface unit, USB-serial signal converting unit, RS-422 signal processing unit and RS-422 interface, also comprise signal isolated location, described signal isolated location is placed between described USB-serial signal converting unit and described RS-422 signal processing unit, for USB-serial signal converting unit described in electrical isolation and the signal between described RS-422 signal processing unit.
Preferably, in above-mentioned USB (universal serial bus)-balanced voltage digital interface converter, described signal isolated location comprises the first signal isolated location and secondary signal isolated location;
The input end of described first signal isolated location is connected with described USB-serial signal converting unit, the output terminal of described first signal isolated location is connected with described RS-422 signal processing unit, and described first signal isolated location is used for the signal that electrical isolation is transmitted from described USB-serial signal converting unit to described RS-422 signal processing unit direction;
The input end of described secondary signal isolated location is connected with described RS-422 signal processing unit, the output terminal of described secondary signal isolated location is connected with described USB-serial signal converting unit, and described secondary signal isolated location is used for the signal that electrical isolation is transmitted from described RS-422 signal processing unit to described USB-serial signal converting unit direction.
Preferably, in above-mentioned USB (universal serial bus)-balanced voltage digital interface converter, described first signal isolated location comprises: the first driver, the first photo-coupler, the first resistor, the second resistor, the 3rd resistor, the first electric capacity and the second electric capacity;
The input end of described first driver is connected with described USB-serial signal converting unit, and the output terminal of described first driver connects the negative electrode of the light emitting diode of described first photo-coupler by described first resistor;
The anode of the light emitting diode of described first photo-coupler is all connected with power supply with the power pin of described first driver;
The collector of the triode of described first photo-coupler is connected with the first end of described second resistor, and the second end of described second resistor outputs signal to described RS-422 signal processing unit as the output terminal of described first signal isolated location;
Described 3rd resistor and described first Capacitance parallel connection, one end of described 3rd resistor is connected with the base stage of the triode of described first photo-coupler, the other end is connected with the second end of described second resistor, and the base stage of the triode of described first photo-coupler is connected with power supply;
The emitter of described first photo-coupler is connected with earth terminal;
One end of described second electric capacity is connected with the second end of described second resistor, and the other end is connected with earth terminal.
Preferably, in above-mentioned USB (universal serial bus)-balanced voltage digital interface converter, described secondary signal isolated location comprises:
Second photo-coupler, the 4th resistor, the 5th resistor, the 6th resistor, the 3rd electric capacity;
The negative electrode of the light emitting diode in described second photo-coupler is connected with the first end of described 4th resistor, and the second end of described 4th resistor, as the input end of described secondary signal isolated location, receives the signal from described RS-422 signal processing unit;
The anode of the light emitting diode in described second photo-coupler connects power supply;
The collector of the triode in described second photo-coupler is connected with the first end of described 5th resistor, and the second end of described 5th resistor outputs signal to described USB-serial signal converting unit as the output terminal of described secondary signal isolated location;
The first end of described 6th resistor is connected with the collector of the triode in described second photo-coupler, the second termination power;
The base stage of the triode in described second photo-coupler connects power supply;
The emitter of the triode in described second photo-coupler connects earth terminal;
The first end of described 3rd electric capacity is connected with the first end of described 5th resistor, and the second end of described 3rd electric capacity is connected with the second end of described 6th resistor.
Known via above-mentioned technical scheme, compared with prior art, the present invention adopts isolation scheme, under the prerequisite ensureing proper communication function and signal transmission quality, cut off the electrical connection of signal transmission line computer and PLC, thus stop the fault that causes because of electric leakage communication chip to burn.
Accompanying drawing explanation
In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only embodiments of the invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to the accompanying drawing provided.
The structured flowchart of the USB (universal serial bus) that Fig. 1 provides for the embodiment of the present invention-balanced voltage digital interface converter;
Another structured flowchart of the USB (universal serial bus) that Fig. 2 provides for the embodiment of the present invention-balanced voltage digital interface converter;
The structural representation of the signal isolated location that Fig. 3 provides for the embodiment of the present invention.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.
A kind of structural representation of USB (universal serial bus)-balanced voltage digital interface converter is shown with reference to figure 1, Fig. 1.
USB (universal serial bus)-balanced voltage digital interface converter comprises: usb interface unit, USB-serial signal converting unit, RS-422 signal processing unit and RS-422 interface, above-mentioned converter also comprises signal isolated location, signal isolated location is placed between USB-serial signal converting unit and RS-422 signal processing unit, for the signal between electrical isolation USB-serial signal converting unit and RS-422 signal processing unit.
In prior art, USB turns serial port chip and is directly connected with RS-422 transceiving chip, directly be connected with RS-422 transceiving chip because USB turns serial port chip, have path electrically to exist, and the present invention employs signal isolated location in design, the Signal transmissions of signal isolated location between converter two ends carries out electrical isolation, under the prerequisite ensureing proper communication function and signal transmission quality, cut off the electrical connection of signal transmission line computer and PLC, thus stop the fault that causes because of electric leakage communication chip to burn.
With reference to figure 2, above-mentioned signal isolated location can comprise the first signal isolated location U11 and secondary signal isolated location U12.
The input end of the first signal isolated location U11 is connected with USB-serial signal converting unit, the output terminal of the first signal isolated location U11 is connected with described RS-422 signal processing unit, and the first signal isolated location U11 is used for the signal that electrical isolation is transmitted from USB-serial signal converting unit to RS-422 signal processing unit direction.
The input end of secondary signal isolated location U12 is connected with RS-422 signal processing unit, the output terminal of secondary signal isolated location U12 is connected with USB-serial signal converting unit, and secondary signal isolated location U12 is used for the signal that electrical isolation is transmitted from RS-422 signal processing unit to USB-serial signal converting unit direction.
With reference to figure 3, show a kind of structural representation of above-mentioned isolated location.
First signal isolated location U11 comprises the first driver 111, first photo-coupler 112, first resistor R1, the second resistor R2, the 3rd resistor R3, the first electric capacity C1 and the second electric capacity C2, wherein, the resistance of the first resistor R1 is 470 Ω, the resistance of the second resistor R2 is 100 Ω, the resistance of the 3rd resistor R3 is 1000 Ω, the capacitance of the first electric capacity C1 is 0.1 microfarad, and the capacitance of the second electric capacity C2 is 3900 pico farads.
The serial output signal from USB-serial signal converting unit is amplified in the effect of the first driver 111, because photo-coupler 112 needs the drive current of about 10mA, and the serial output signal intensity that USB-serial signal converting unit exports is not enough to Direct driver photo-coupler, so need increase driver 111 to drive serial output signal by photo-coupler 112.
Pin in first driver 111
for exporting control pin, pin A is input pin, and pin GND is grounding leg, and pin Y is output pin, and pin VCC is supply pin.
The model of the first driver 111 can be SN74AHCT1G125, shown in figure 3,
for exporting control pin, Low level effective.When
when connecing low level, the first driver 111 works, and by the signal inputted from pin A, is exported by pin Y; When
when connecing high level, the first driver 111 does not work, and why the signal that is no matter pin A inputs is worth, and pin Y does not export.In the design, because needs first driver 111 works all the time, so pin A is connected with earth terminal.Pin GND is grounding leg, connects earth terminal; The positive 5V power supply VCC that pin VCC is connected to USB side holds.
The input end A of the first driver 111 is connected with USB-serial signal converting unit as the input end 1 of the first signal isolated location U11, and the output terminal Y of the first driver 111 connects the negative electrode of the light emitting diode of the first photo-coupler 112 by the first resistor R1.
The anode of the light emitting diode of the first photo-coupler 112 is connected with power supply VCC, and power supply is positive 5 volts of voltages of USB side power supply;
The collector of the triode of the first photo-coupler 112 is connected with output terminal 2 by the second resistor R2, and output terminal 2 outputs signal to described RS-422 signal processing unit as the output terminal of the first signal isolated location U1;
3rd resistor R3 is in parallel with the first electric capacity C1, one end of 3rd resistor R3 is connected with the base stage of the triode of the first photo-coupler 112, the other end is connected with the output terminal 2 of the first signal isolated location U1, the base stage of the triode of the first photo-coupler 112 is connected to power supply VCC1, power supply is positive 5 volts of end power supplys of RS-422 side, and acquiescence output level during no-output is drawn high high level;
The emitter of the first photo-coupler 112 is connected with earth terminal, earth terminal be RS-422 side power supply " " end;
One end of second electric capacity C2 is connected with output terminal 2, and the other end is connected with earth terminal, earth terminal be RS-422 side power supply " " end.
These two electric capacity of first electric capacity C1 and the second electric capacity C2 can play the effect of filtering high frequency noise.
Above-mentioned secondary signal isolated location U2 comprises the second photo-coupler 123, the 4th resistor R4, the 5th resistor R5, the 6th resistor R6 and the 3rd electric capacity C3, wherein, the capacitance that the resistance of the 4th resistor R4 is 100 Ω, the resistance of the 5th resistor R5 is 100 Ω, the resistance of the 6th resistor R6 is 1000 Ω and the 3rd electric capacity C3 is 0.1 microfarad.
The negative electrode of the light emitting diode in the second photo-coupler 123 is connected with input end 3 by the 4th resistor R4, and input end 3 is the input end of secondary signal isolated location U2, and it receives the signal from RS-422 signal processing unit;
The anode of the light emitting diode in the second photo-coupler 123 meets power supply VCC1, and power supply is positive 5 volts of power supplys of RS-422 side;
The collector of the triode in the second photo-coupler 123 is connected with output terminal 4 by the 5th resistor R5, output terminal 4 is the output terminal of secondary signal isolated location U2, and its output terminal as secondary signal isolated location outputs signal to USB-serial signal converting unit;
The first end of the 6th resistor R6 is connected with the collector of the triode in the second photo-coupler 123, the second termination power, and power supply is positive 5 volts of power supplys of USB side, and acquiescence output level during no-output is drawn high high level;
The base stage of the triode in the second photo-coupler 123 connects power supply, and power supply is positive 5 volts of power supplys of USB side;
The emitter of the triode in the second photo-coupler 123 connects earth terminal, and earth terminal is the earth terminal of USB side;
The first end of the 3rd electric capacity C3 is connected with output terminal 4, and second end of the 3rd electric capacity C3 is connected with the second end of the 6th resistor.
Preferably, the model of above-mentioned first photo-coupler and the second coupling mechanism can be PS9114.
The following describes the course of work of the first signal isolated location and secondary signal isolated location, for the course of work of the first signal isolated location, the first signal isolated location realizes the electrical isolation in signal direction from USB to RS-422; And the first signal isolated location realizes the electrical isolation in signal direction from RS-422 to USB, its principle of work is identical, and just signal flows to direction difference, therefore no longer repeats.
Signal (hereinafter referred to as " input signal ") from USB side inputs from the input end A of the first driver 111, first driver 111 exports from pin Y after being amplified by signal, is connected to the negative electrode of diode in the first photo-coupler 112 by the first resistor R1.
When input signal is high level, in first photo-coupler 112, the negative electrode of light emitting diode is high level, anode is also high level, therefore light emitting diode is not luminous, and triode not conducting because not receiving light signal in the first photo-coupler 112, so output terminal 2 draws high high level by the 3rd resistor R3.
When input signal is low level, in first photo-coupler 112, the negative electrode of light emitting diode is low level, anode is high level, lumination of light emitting diode, triode conducting because receiving light signal in first photo-coupler 112, so output terminal 2 is pulled down to low level by the second resistor R2.
By the conversion of the electric signal-light signal-electric signal of the first photo-coupler 112, achieve the high and low level signal of transmission, and the function that isolation is directly electrically connected.
Photo-coupler inside in the embodiment of the present invention is made up of optical transmitting set (light emitting diode) and optical receiver (triode), and the electric signal of input photo-coupler inside is converted to light signal through optical transmitting set, then is converted to electric signal output by optical receiver.The electrical isolation of input end and output terminal is realized by the transfer process of this " electrical-optical-electricity ".And signal can only from input end to output terminal one-way transmission, and the signal level maximum magnitude that output terminal exports is determined by circuit of output terminal.During due to the reasons such as static discharge, short circuit, the electric leakage electric voltage exception of generation somewhere in the entire system, photo-coupler can prevent this abnormal voltage from arriving the other end by photo-coupler and form path, under the prerequisite ensureing proper communication function and signal transmission quality, cut off the electrical connection of signal transmission line computer and PLC, thus stop the fault that causes because of electric leakage communication chip to burn.
To the above-mentioned explanation of the disclosed embodiments, professional and technical personnel in the field are realized or uses the present invention.To be apparent for those skilled in the art to the multiple amendment of these embodiments, General Principle as defined herein can without departing from the spirit or scope of the present invention, realize in other embodiments.Therefore, the present invention can not be restricted to these embodiments shown in this article, but will meet the widest scope consistent with principle disclosed herein and features of novelty.
Claims (4)
1. USB (universal serial bus)-balanced voltage digital interface converter, comprise usb interface unit, USB-serial signal converting unit, RS-422 signal processing unit and RS-422 interface, it is characterized in that, also comprise signal isolated location, described signal isolated location is placed between described USB-serial signal converting unit and described RS-422 signal processing unit, for USB-serial signal converting unit described in electrical isolation and the signal between described RS-422 signal processing unit, under the prerequisite ensureing proper communication function and signal transmission quality, the electrical connection of shutoff signal transmission line computer and PLC.
2. USB (universal serial bus) according to claim 1-balanced voltage digital interface converter, is characterized in that,
Described signal isolated location comprises the first signal isolated location and secondary signal isolated location;
The input end of described first signal isolated location is connected with described USB-serial signal converting unit, the output terminal of described first signal isolated location is connected with described RS-422 signal processing unit, and described first signal isolated location is used for the signal that electrical isolation is transmitted from described USB-serial signal converting unit to described RS-422 signal processing unit direction;
The input end of described secondary signal isolated location is connected with described RS-422 signal processing unit, the output terminal of described secondary signal isolated location is connected with described USB-serial signal converting unit, and described secondary signal isolated location is used for the signal that electrical isolation is transmitted from described RS-422 signal processing unit to described USB-serial signal converting unit direction.
3. USB (universal serial bus) according to claim 2-balanced voltage digital interface converter, it is characterized in that, described first signal isolated location comprises: the first driver, the first photo-coupler, the first resistor, the second resistor, the 3rd resistor, the first electric capacity and the second electric capacity;
The input end of described first driver is connected with described USB-serial signal converting unit, and the output terminal of described first driver connects the negative electrode of the light emitting diode of described first photo-coupler by described first resistor;
The anode of the light emitting diode of described first photo-coupler is all connected with power supply with the power pin of described first driver;
The collector of the triode of described first photo-coupler is connected with the first end of described second resistor, and the second end of described second resistor outputs signal to described RS-422 signal processing unit as the output terminal of described first signal isolated location;
Described 3rd resistor and described first Capacitance parallel connection, one end of described 3rd resistor is connected with the base stage of the triode of described first photo-coupler, the other end is connected with the second end of described second resistor, and the base stage of the triode of described first photo-coupler is connected with power supply;
The emitter of described first photo-coupler is connected with earth terminal;
One end of described second electric capacity is connected with the second end of described second resistor, and the other end is connected with earth terminal.
4. USB (universal serial bus) according to claim 2-balanced voltage digital interface converter, is characterized in that, described secondary signal isolated location comprises:
Second photo-coupler, the 4th resistor, the 5th resistor, the 6th resistor, the 3rd electric capacity;
The negative electrode of the light emitting diode in described second photo-coupler is connected with the first end of described 4th resistor, and the second end of described 4th resistor, as the input end of described secondary signal isolated location, receives the signal from described RS-422 signal processing unit;
The anode of the light emitting diode in described second photo-coupler connects power supply;
The collector of the triode in described second photo-coupler is connected with the first end of described 5th resistor, and the second end of described 5th resistor outputs signal to described USB-serial signal converting unit as the output terminal of described secondary signal isolated location;
The first end of described 6th resistor is connected with the collector of the triode in described second photo-coupler, the second termination power;
The base stage of the triode in described second photo-coupler connects power supply;
The emitter of the triode in described second photo-coupler connects earth terminal;
The first end of described 3rd electric capacity is connected with the first end of described 5th resistor, and the second end of described 3rd electric capacity is connected with the second end of described 6th resistor.
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| CN104239262B (en) * | 2014-09-17 | 2017-04-19 | 山东广达锂电检测研究院有限公司 | USB (Universal Serial Bus) to RS-485-422 multifunctional active isolation converter |
| CN106991063A (en) * | 2014-09-17 | 2017-07-28 | 葛云龙 | USB turns the active isolating converters of RS 485 |
| CN107069953B (en) * | 2017-02-27 | 2024-05-03 | 上海华宿电气股份有限公司 | Monitoring system based on power bus information |
| CN107896152A (en) * | 2017-12-28 | 2018-04-10 | 黑龙江龙电电气有限公司 | Multi-channel communication sharing device and method |
| CN115277371A (en) * | 2022-07-15 | 2022-11-01 | 南京熊猫电子制造有限公司 | Modular CAN communication isolation circuit system |
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