CN205005065U - RS485 communication circuit - Google Patents
RS485 communication circuit Download PDFInfo
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- CN205005065U CN205005065U CN201520740190.0U CN201520740190U CN205005065U CN 205005065 U CN205005065 U CN 205005065U CN 201520740190 U CN201520740190 U CN 201520740190U CN 205005065 U CN205005065 U CN 205005065U
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Abstract
The utility model relates to a RS485 communication circuit, including main control chip, still include data transmission and make ability photoelectric isolation module, data receipt photoelectric isolation module and data receiving and dispatching processing module, the utility model provides a cost is lower and can receive idiopathetic RS485 communication circuit certainly.
Description
Technical field
The utility model relates to a kind of RS485 communicating circuit.
Background technology
Usually, in industrial automation, as in power industry reactive power compensation management system, Intelligent capacitor needs capacitor networking, data acquisition, control and management etc., is generally realized by fieldbus.Fieldbus kind is more, as RS485 bus, CAN, MBUS bus etc.Wherein RS485 bus hardware cost is low, easily realizes, the features such as good reliability, so be widely used in industrial automation.
RS485 is a kind of serial communication link layer protocol being widely used in industrial communication interface, transmitting based on differential signal.There is the advantages such as antijamming capability is strong, long transmission distance, belong to half-duplex operation.
Generally, for realizing RS485 communication, hardware circuit at least needs Master control chip (MCU) and RS485 communication module, main control chip (MCU) needs use three holding wires to be connected with communication interface chip, these three holding wires are data signal recipients (RXD), data-signal transmitting terminal (serial ports transmission pin), the data reception/transmission control end (CTR) of main control chip respectively, be connected with RS485 communication interface module respectively, as shown in Figure 1.Wherein the holding wire of data signal recipients (RXD) and data-signal transmitting terminal (serial ports transmission pin) generally uses the lead-in wire of the asynchronous serial communication mouth of main control chip (MCU), the I/O port that data reception/transmission control end (CTR) generally uses main control chip (MCU) common.These three holding wires are connected with RS485 communication interface chip, wherein data-signal transmitting terminal (serial ports transmission pin) is connected with the data input pin (DI) of RS485 communication interface chip, data flow is from main control chip (CPU) to RS485 communication interface module, as illustrated by the arrows in fig. 1, show that data that main control chip (MCU) sends are transferred to the data input pin (DI) of RS485 communication interface chip by signal sending end (serial ports transmission pin) lead-in wire; Data signal recipients (RXD) is connected with the data output end (RO) of RS485 communication interface module, data flow is from RS485 communication interface chip to main control chip (MCU), as illustrated by the arrows in fig. 1, show that number of buses that RS485 communication chip receives is transferred to the data signal recipients (RXD) of main control chip (MCU) from the data output end (RO) of RS485 communication interface chip; The data reception/transmission control end (CTR) of main control chip (MCU) is connected with the data reception/transmission Enable Pin (RE/DE) of RS485 communication interface chip, data flow is from main control chip (CPU) to RS485 communication interface chip, as illustrated by the arrows in fig. 1.Under current background technology, if consider electromagnetic compatibility (EMC) performance and the communication isolation needs of device, Phototube Coupling process can also be carried out respectively to three holding wires of above-mentioned main control chip (CPU), make communication interface part and main control part realize electrical isolation.
The weak point that current technology also exists is: first, because application of installation is in industrial occasions, a large amount of electromagnetic interference signals is there is around device, comprise the interference signal that some are introduced from RS485 bus, in addition the interference of device internal circuit, the bus communication ability actual performance of RS485 is reduced, as in communication distance shortening, bus, the quantity of connected node reduces.Secondly, data communication flows to be needed to control (CTR) separately, increases cost of hardware design.Again, because RS485 communication is half duplex communication, can not internal loopback be realized, in use bring a lot of inconvenience.Finally, in order to realize RS485 communication, independent RS485 communication module must be used, add very large hardware development cost.
Utility model content
Goal of the invention of the present utility model is the limitation solving above-mentioned existing a kind of RS485 communicating circuit, and it is lower and can from receiving spontaneous RS485 communicating circuit that the utility model provides a kind of cost.
The utility model comprises main control chip, also comprises data and sends and enable photoelectric isolation module, data receiver photoelectric isolation module and data transmit-receive processing module; Described main control chip comprises serial ports and sends pin, sends enable control pin and serial ports reception pin; Described data transmission and the input of enable photoelectric isolation module send pin with the serial ports of described main control chip and send enable control pin and be connected, and output is connected with data transmit-receive processing module; The input of described data receiver photoelectric isolation module is connected with described data transmit-receive processing module, and output receives pin with described main control chip serial ports and is connected; One end of described data transmit-receive processing module sends with data and enable photoelectric isolation module and data receiver photoelectric isolation module are connected, and the other end connects RS485 bus.
After adopting above structure, the utility model compared with prior art, has the following advantages:
A kind of RS485 communicating circuit of the utility model not only achieves the communication function of RS485, also achieve the control by sending optocoupler two input pin control realization transmissions, receiving function, thus decrease RS485 transceiver communication control pin isolation optocoupler, thus reduce design cost, the more important thing is, present invention eliminates standard RS485 communication chip, greatly reduce the cost of RS485 communication system, also achieve the internal loopback function that half-duplex RS 485 communicates, thus achieve RS485 communication single channel self-checking function.This distribution RS485 telecommunication circuit comprises signal photoelectric isolation module, the parts such as RS485 communication interface modules.
As improvement, described data transmit-receive processing module comprises triode, voltage stabilizing didoe, one-way conduction diode, current-limiting resistance, pull down resistor, the first divider resistance, the second divider resistance, pull-up resistor; The plus earth of described voltage stabilizing didoe, negative electrode is connected with described current-limiting resistance; One end ground connection of described pull down resistor; The node that described current-limiting resistance is connected with pull down resistor is connected with the base stage of described triode; The collector electrode of described triode connects power supply by described pull-up resistor; The emitter of described triode is connected with the anode of described one-way conduction diode; The first described divider resistance is connected with the negative electrode of the second divider resistance with described diode.
As improvement, described data send and enable photoelectric isolation module comprises the first Phototube Coupling optocoupler; 1 pin of the first described Phototube Coupling optocoupler is connected with the enable control pin of described transmission, and 2 pin and described serial ports receive pin and be connected, and 3 pin are by described pull down resistor R2 ground connection, and 4 pin connect insulating power supply.
As improvement, described data receiver photoelectric isolation module comprises the second Phototube Coupling optocoupler, and 1 pin of the second described Phototube Coupling optocoupler is connected with the second divider resistance with the first described divider resistance, 2 pin ground connection, 3 pin connect VSS end, and 4 pin connect serial ports and receive pin.
Accompanying drawing explanation
Fig. 1 is existing RS485 tri-light-coupled isolation communicating circuit structured flowchart.
Fig. 2 is circuit structure block diagram of the present invention.
Fig. 3 is circuit theory diagrams of the present invention.
Embodiment
Below in conjunction with the drawings and specific embodiments, the utility model is described in further detail.
The utility model comprises main control chip MCU as Figure 2-3, also comprises data and sends and enable photoelectric isolation module, data receiver photoelectric isolation module and data transmit-receive processing module; Described main control chip MCU comprises serial ports and sends pin TXD, sends enable control pin CTR and serial ports reception pin RXD; Described data transmission and the input of enable photoelectric isolation module send pin TXD with the serial ports of described main control chip MCU and send enable control pin CTR and be connected, and output is connected with data transmit-receive processing module; The input of described data receiver photoelectric isolation module is connected with described data transmit-receive processing module, and output receives pin RXD with described main control chip MCU serial ports and is connected; One end of described data transmit-receive processing module sends with data and enable photoelectric isolation module and data receiver photoelectric isolation module are connected, and the other end connects RS485 bus.Described data transmit-receive processing module comprises triode Q1, voltage stabilizing didoe D1, one-way conduction diode D2, current-limiting resistance R1, pull down resistor R2, the first divider resistance R3, the second divider resistance R4, pull-up resistor R5; The plus earth of described voltage stabilizing didoe D1, negative electrode is connected with described current-limiting resistance R1; One end ground connection of described pull down resistor R2; The node that described current-limiting resistance R1 is connected with pull down resistor R2 is connected with the base stage of described triode Q1; The collector electrode of described triode Q1 connects power supply by described pull-up resistor R5; The emitter of described triode Q1 is connected with the anode of described one-way conduction diode D2; The first described divider resistance R3 is connected with the negative electrode of described diode D2 with the second divider resistance R4.Described data send and enable photoelectric isolation module comprises the first Phototube Coupling optocoupler; 1 pin of the first described Phototube Coupling optocoupler is connected with described transmission enable control pin CTR, and 2 pin and described serial ports receive pin RXD and be connected, and 3 pin are by described pull down resistor R2 ground connection, and 4 pin connect insulating power supply.Described data receiver photoelectric isolation module comprises the second Phototube Coupling optocoupler, and 1 pin of the second described Phototube Coupling optocoupler is connected with the second divider resistance R4 with the first described divider resistance R3,2 pin ground connection, and 3 pin connect VSS end, and 4 pin connect serial ports and receive pin RXD.
As shown in Figure 3, be compared to the existing RS485 tri-optocoupler communicating circuit structured flowchart shown in Fig. 1, first the utility model eliminates RS485 transmitting-receiving and controls isolation optocoupler, will receive and dispatch controlled loading and send on signal isolation optocoupler to data.Secondly, standard RS485 communication chip has been changed into data transmit-receive control circuit of the present utility model.Again, be loaded into sending signal the internal loopback function receiving and data-signal realizes half-duplex RS 485 and communicate simultaneously.
Just specific implementation process of the present utility model makes elaboration below, for helping understanding of the present utility model.
Data transmission procedure, the transmission enable control pin CTR of described main control chip MCU is connected to 1 pin of the first Phototube Coupling optocoupler as RS485 communication transmission data enable control port, and the serial ports of main control chip MCU sends pin TXD and is connected to 2 pin of the first Phototube Coupling optocoupler as RS485 communication transmission FPDP.When enable control pin output low level " 0 ", no matter serial ports sends pin TXD exports high point flat " 1 " or output low level " 0 ", and the first Phototube Coupling optocoupler is all in cut-off state, and data can not send.When the enable control pin CTR of transmission exports high point flat " 1 " be, serial ports sends the flat 5V of pin TXD output signal " 1 " height point, first Phototube Coupling optocoupler cut-off, transistor base voltage is 0V, triode ends, RS485_B terminal voltage is-0.7V, then the voltage of RS485_A end is greater than more than the voltage 200mV of RS48_B, then RS485 bus produces differential signal " 1 "; Serial ports sends pin TXD and outputs signal " 0 " low level 0V, first Phototube Coupling optocoupler conducting, transistor base is high voltage 5V, triode ON, the flat 5V of the very high point of triode emission, one-way conduction diode current flow, RS485_B terminal voltage is 5V, then the voltage of RS485_A end is less than more than the voltage 200mV of RS48_B, then RS485 bus produces differential signal " 0 ", the transmission of this circuit realiration RS485 differential signal " 0 " and " 1 ".
DRP data reception process, the pin of described main control chip MCU is connected to 4 pin of the second Phototube Coupling optocoupler as RS485 communication reception FPDP.When enable control pin CTR port output low level " 0 " of transmission, RS485 communication is in system and sends state, when the total scene of RS485 produces differential signal " 1 ", then RS485_A port voltage is greater than RS485_B port voltage, then N2 Phototube Coupling optocoupler cut-off, it is signal one state that serial ports receives pin RXD port status; When the total scene of RS485 produces differential signal " 0 ", then RS485_A port voltage is less than RS485_B port voltage, then the second Phototube Coupling optocoupler conducting, RXD port status is signal " 0 " state, the reception of RS485 differential signal " 0 " and " 1 " of this circuit realiration.
Internal loopback process, when RS485 communication is in transmission state, serial ports sends pin TXD port and sends signal " 1 ", then RS485_B port is in low level, then the second Phototube Coupling optocoupler cut-off, when serial ports reception pin RXD ports port signal is " 1 "; Serial ports sends pin TXD port when sending signal " 0 ", to be then in high point flat for RS485_B port, then the second Phototube Coupling optocoupler conducting, and it be " 0 " that serial ports receives pin RXD ports port signal, the internal loopback function that this circuit realiration RS485 communicates.
Below only just most preferred embodiment of the present utility model is described, but can not be interpreted as it is limitations on claims.The utility model is not limited only to above embodiment, and all various changes done in the protection range of the utility model independent claims are all in protection range of the present utility model.
Claims (4)
1. a RS485 communicating circuit, comprises main control chip MCU, it is characterized in that: also comprise data and send and enable photoelectric isolation module, data receiver photoelectric isolation module and data transmit-receive processing module; Described main control chip MCU comprises serial ports and sends pin TXD, sends enable control pin CTR and serial ports reception pin RXD; Described data transmission and the input of enable photoelectric isolation module send pin TXD with the serial ports of described main control chip MCU and send enable control pin CTR and be connected, and output is connected with data transmit-receive processing module; The input of described data receiver photoelectric isolation module is connected with described data transmit-receive processing module, and output receives pin RXD with the serial ports of described main control chip MCU and is connected; One end of described data transmit-receive processing module sends with described data and enable photoelectric isolation module and data receiver photoelectric isolation module are connected, and the other end connects RS485 bus.
2. a kind of RS485 communicating circuit according to claim 1, is characterized in that: described data transmit-receive processing module comprises triode Q1, voltage stabilizing didoe D1, one-way conduction diode D2, current-limiting resistance R1, pull down resistor R2, the first divider resistance R3, the second divider resistance R4, pull-up resistor R5; The plus earth of described voltage stabilizing didoe D1, negative electrode is connected with described current-limiting resistance R1; One end ground connection of described pull down resistor R2; The node that described current-limiting resistance R1 is connected with pull down resistor R2 is connected with the base stage of described triode Q1; The collector electrode of described triode Q1 connects power supply by described pull-up resistor R5; The emitter of described triode Q1 is connected with the anode of described one-way conduction diode D2; The first described divider resistance R3 is connected with the negative electrode of described diode D2 with the second divider resistance R4.
3. a kind of RS485 communicating circuit according to claim 2, is characterized in that: described data send and enable photoelectric isolation module comprises the first Phototube Coupling optocoupler; 1 pin of the first described Phototube Coupling optocoupler is connected with described transmission enable control pin CTR, and 2 pin and described serial ports receive pin RXD and be connected, and 3 pin are by described pull down resistor R2 ground connection, and 4 pin connect insulating power supply.
4. a kind of RS485 communicating circuit according to claim 2, it is characterized in that: described data receiver photoelectric isolation module comprises the second Phototube Coupling optocoupler, 1 pin of the second described Phototube Coupling optocoupler is connected with the second divider resistance R4 with the first described divider resistance R3,2 pin ground connection, 3 pin connect VSS end, and 4 pin connect serial ports and receive pin RXD.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520740190.0U CN205005065U (en) | 2015-09-23 | 2015-09-23 | RS485 communication circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520740190.0U CN205005065U (en) | 2015-09-23 | 2015-09-23 | RS485 communication circuit |
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| CN205005065U true CN205005065U (en) | 2016-01-27 |
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| CN201520740190.0U Expired - Fee Related CN205005065U (en) | 2015-09-23 | 2015-09-23 | RS485 communication circuit |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105141491A (en) * | 2015-09-23 | 2015-12-09 | 杭州得诚电力科技有限公司 | RS485 communication circuit capable of achieving self-sending and self-receiving and method |
| CN107426526A (en) * | 2016-05-23 | 2017-12-01 | 中国科学院沈阳自动化研究所 | Material data collecting transmitter based on F800 weight batching controllers |
| CN110855316A (en) * | 2019-10-25 | 2020-02-28 | 天津航空机电有限公司 | RS485 automatic receiving and transmitting isolation circuit |
-
2015
- 2015-09-23 CN CN201520740190.0U patent/CN205005065U/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105141491A (en) * | 2015-09-23 | 2015-12-09 | 杭州得诚电力科技有限公司 | RS485 communication circuit capable of achieving self-sending and self-receiving and method |
| CN105141491B (en) * | 2015-09-23 | 2023-05-09 | 杭州得诚电力科技股份有限公司 | RS485 communication circuit and method for realizing spontaneous self-receiving |
| CN107426526A (en) * | 2016-05-23 | 2017-12-01 | 中国科学院沈阳自动化研究所 | Material data collecting transmitter based on F800 weight batching controllers |
| CN107426526B (en) * | 2016-05-23 | 2024-03-05 | 中国科学院沈阳自动化研究所 | Material data acquisition and transmission device based on F800 weight batching controller |
| CN110855316A (en) * | 2019-10-25 | 2020-02-28 | 天津航空机电有限公司 | RS485 automatic receiving and transmitting isolation circuit |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20160127 Termination date: 20180923 |
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| CF01 | Termination of patent right due to non-payment of annual fee |