CN107908584B - Multi-path RS-485 communication network - Google Patents
Multi-path RS-485 communication network Download PDFInfo
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Abstract
The invention discloses a multi-channel RS-485 communication network, which is used for realizing multi-channel RS-485 communication by using limited serial port resources, and comprises a DSP digital signal processor, a channel switching control circuit, an RS-485 interface circuit and an RS-485 communication terminal, and is characterized in that: the RS-485 communication terminals are all connected with the same serial communication port, and the channel selection signal output by the DSP is used for enabling the RS-485 interface circuit after passing through the channel switching control circuit. The invention can realize multi-path RS-485 communication through a single serial port without programmable devices such as FPGA and the like, and solves the technical problems of higher cost, higher expansion and modification cost, complex design and inconvenience for transplantation in the prior art.
Description
Technical Field
The invention relates to a multi-channel communication network, in particular to a multi-channel RS-485 communication network.
Background
With the continuous improvement of digitalization and informatization of various systems, the requirement on information sharing of various measurement control units is higher and higher, and the cross-linking between devices is more and more complex. The communication interface is the basis for realizing mutual cross-linking of the devices, because a singlechip or a DSP digital signal processing system usually only has two serial interfaces, one serial interface of the traditional use method can only realize one RS-485 full-duplex communication, and can not directly meet the use requirements of a new generation of measurement control systems, especially when a plurality of asynchronous communication cross-linking devices simultaneously need information interaction. If a user wants to guarantee high-reliability communication requirements and system anti-interference capability in limited hardware resources and realize multi-channel communication exchange, a multi-channel RS-485 communication network is needed.
In the prior art, a communication soft core is designed and developed by using programmable devices such as an FPGA (field programmable gate array) and the like, and multi-channel RS-485 communication is realized by adopting internal logic control, wherein a logic diagram of the communication soft core is shown in figure 1. However, the multi-path RS-485 communication network designed by using the FPGA chip has high cost, high expansion and modification cost, small temperature application range (-40 ℃ to +60 ℃), high design and development complexity and high technical difficulty, and is generally not suitable for being transplanted on embedded systems such as a single chip microcomputer system and a DSP digital signal processing system.
Therefore, in the prior art, the multi-path RS-485 communication network has the technical problems of high cost, high expansion and modification cost, small temperature application range, complex design and inconvenience in transplantation.
Disclosure of Invention
The invention provides a multi-path RS-485 communication network for solving the technical problems of higher cost, higher expansion and modification cost, small temperature application range, high design technology difficulty and inconvenience in transplantation in the prior art.
The invention provides a multi-channel RS-485 communication network which comprises a DSP digital signal processor, a channel switching control circuit, at least 3 identical and independent RS-485 interface circuits and at least 3 independent RS-485 communication terminals, wherein each RS-485 communication terminal is provided with an RS-485 communication interface and the number of the RS-485 communication interfaces is consistent with that of the RS-485 interface circuits; the RS-485 communication terminal is connected with the RS-485 interface circuit in a one-to-one manner to form a plurality of communication channels; the RS-485 interface circuit is used for converting a DSP serial interface communication protocol and an RS-485 serial interface communication protocol; the method is characterized in that: the channel switching control circuit is connected between the DSP and the RS-485 interface circuit and is used for realizing level conversion between the DSP and the RS-485 interface circuit and protection of pins of the DSP; the DSP is used for outputting controllable channel selection signals, receiving and sending data information of a plurality of communication channels and configuring and binding information formats of sent contents; the channel selection signal is transmitted to the RS-485 interface circuit after passing through the channel switching control circuit and is used for enabling the RS485 interface circuit; and the RS-485 communication interfaces of the RS-485 communication terminals are connected with the same serial communication port of the DSP digital signal processor through the corresponding RS-485 interface circuit and the channel switching control circuit. The principle is as follows: each RS-485 interface circuit is respectively connected with one RS-485 communication terminal to form one communication channel, all the communication channels are connected to the same serial port of the DSP, and then the RS-485 interface circuit is controlled by enabling signals of the output channel of the DSP, so that the communication and disconnection between the DSP and one RS-485 communication terminal are controlled. The controllable channel selection signal is determined according to a pre-prepared transceiver mechanism of the DSP digital signal processor: namely, when needing to communicate with a certain RS-485 communication terminal, the channel selection signal enabling the RS-485 interface circuit of the path is output to gate the communication channel of the path. Meanwhile, signals between the DSP and the RS-485 interface circuit are subjected to level switching through the channel switching control circuit and are converted into appropriate driving levels. The switching and information exchange of the multi-channel RS-485 communication channel can be realized by utilizing the channel selection signal output by the DSP and assisting the level conversion of the channel switching control circuit, so that the information exchange and sharing with a plurality of peripheral communication terminals can be realized only by configuring a reasonable transceiving mechanism in the DSP, and the communication soft core is not required to be designed and developed by programmable devices such as an FPGA (field programmable gate array) and the like.
Furthermore, the RS-485 interface circuit comprises a sending enabling end, a receiving enabling end, a DSP serial port used for being connected with the channel switching control circuit, and an RS-485 full-duplex serial port used for being connected with the RS-485 communication terminal; the DSP serial port comprises two ports, one port is used as a signal input port, and the other port is used as a signal output port; the RS-485 full-duplex serial port comprises 4 ports, wherein two ports are used as differential signal input ports, and the other two pairs are used as differential signal output ports; the transmitting enabling end controls the output of a differential signal output port of the RS-485 full-duplex serial port to be in a high-impedance state or outputs a corresponding value according to the level value of a signal input port of the DSP serial port; and the receiving enabling end controls the DSP serial port output port to be in a high-impedance state or outputs a corresponding value according to the level value of the RS-485 full-duplex serial port differential signal input port. The principle is as follows: in the above mode, the RS-485 interface circuit is an RS-485 full-duplex interface circuit, has 4 ports, can be used for forming an RS-485 full-duplex communication network, can adopt double-end transmission, double-end balanced driving and differential receiving, and is equivalent to two single-end transceivers in each interface circuit, and the balanced driving and differential receiving method can fundamentally eliminate ground wire interference. And the sending and receiving are controlled by the sending enable end and the receiving enable end, and can be controlled by the DSP to be gated.
Furthermore, the DSP digital signal processor function is mainly completed by a DSP chip; the DSP chip is a TMS320C2000 series chip, and a plurality of I/O ports of the DSP chip are connected with the channel switching control circuit and used for outputting channel selection signals; the channel selection signal is converted into a 5V or 0V level signal by the channel switching control circuit and then transmitted to a transmitting enabling end and a receiving enabling end of the RS-485 interface circuit; the DSP chip contains software for realizing initialization setting of a DSP digital signal processor, control of output level of an I/O port, data information receiving and sending of a multi-channel communication channel and configuration of information formats of bound sending contents; and the SCIA serial communication port of the DSP chip is connected with the DSP serial ports in all the RS-485 interface circuits after passing through the channel switching control circuit and is used as a serial communication port finally connected with the RS-485 communication terminal. The principle is as follows: the DSP chip is integrated with a bottom layer driving software of a communication interface circuit and a communication control algorithm software. The bottom driving software of the communication interface circuit mainly configures the internal program space, the data space and the I/O port of the DSP digital signal processor; initializing clock frequency, and inputting and outputting I/O port line state; initializing the transceiving states and modes of serial communication interfaces SCIA and SCIB; and various interrupt service program entries of the DSP. The communication control algorithm software is a communication drive and control algorithm which is designed and developed according to a required communication protocol, and aims to realize that a plurality of RS-485 communication channels share a serial communication interface of a DSP (digital signal processor) and can detect whether the current communication channel works normally or not in real time. The communication control algorithm program software enables the working state of the RS-485 interface circuit by driving and controlling the input/output I/O control bus of the DSP chip, realizes the switching of multiple RS-485 communication channels and information exchange, and achieves the information exchange with peripheral equipment. The working process is as follows: after the basic function of the DSP chip is initialized, sending a control command for enabling an RS-485 interface circuit connected with the RS-485 communication terminal N, and sending the bound data to the RS-485 communication terminal N; after the data transmission is finished, waiting for receiving the data and the state information returned by the RS-485 communication terminal N, closing the current communication channel and quitting the receiving service program; the communication control algorithm software judges the data received by the multiple RS-485 communication channels, enters a fault-tolerant processing flow, starts the fault counting of the current communication channel if the currently received data is wrong or no data is received within a period time, sets the fault flag bit of the current communication peripheral equipment when the continuous fault counting is accumulated to a certain number of times, and immediately clears the fault flag bit after the communication is recovered to be normal, so that the channel fault can be reported in real time, and the detection and the maintenance are convenient. The TMS320C2000 series DSP chip has two serial communication ports, SCIA and SCIB. SCIA is selected to connect with all DSP serial ports in the RS-485 interface circuit to realize the connection with the multi-path RS-485 communication terminal, and a multi-path communication channel is constructed. The I/O of the DSP chip can output TTL level according to internal setting, the TTL level can be converted into a 5V or 0V level signal after passing through the channel switching circuit, the TTL level can be used for driving a sending enabling end and a receiving enabling end of the RS-485 interface circuit, gating and switching of communication channels are achieved, and finally multi-channel RS-485 full-duplex communication is achieved according to a required receiving and sending mechanism.
Further, the main function of the channel switching control circuit is realized by a level conversion chip, and the type of the level conversion chip is selected to be SN74ALVC164245 DL; the A series ports of the level conversion chip are connected with the I/O port of the DSP chip, and the corresponding B series ports are connected with the transmitting enabling end and the receiving enabling end of the RS-485 interface circuit. Specifically, for example, the I/O ports control _1 to control _8 of the DSP chip are used to output channel selection signals, the ports control _1 to control _8 are sequentially connected to the ports 1a1 to 1A8 of the level conversion chip, and the ports 1B1 to 1B8 of the level conversion chip are sequentially connected to the transmit enable terminal and the receive enable terminal of the 4-way RS-485 interface circuit. The principle is as follows: the SN74ALVC164245DL level conversion chip is used, the A series port of the chip is 3.3V standard level, the B series port of the chip is 5.0V standard level, the required level conversion can be realized, and the channel expansion can be realized by selecting a plurality of chips.
Furthermore, the main functions of the RS-485 interface circuit are realized by an RS-485 communication chip, the RS-485 communication chip is selected to be MAX489ESA, an RO port of the RS-485 communication chip is used as a signal output port of a DSP serial port, a DI port of the RS-485 communication chip is used as a signal input port of the DSP serial port, and the RS-485 communication chip is used for being connected with a receiving and transmitting pin of an SCIA serial port communication port of the DSP chip after passing through a channel switching control circuit; an RE port of the RS-485 communication chip is used as a receiving enabling end, and a DE port is used as a sending enabling end; an A port, a B port, a Z port and a Y port of the RS-485 communication chip form an RS-485 full-duplex serial port, wherein the A port and the B port are differential signal input ports, and the Z port and the Y port are differential signal output ports. The principle is as follows: the MAX489ESA is used as a standard RS-485 communication chip, is provided with a sending enabling end, a receiving enabling end and an RS-485 full-duplex serial port, can realize conversion of a serial port protocol, has high integration level, and is a preferred scheme for realizing the invention. The RS-485 interface circuit can be added with some adaptive resistors according to actual requirements, and has the functions of protecting the RS-485 communication chip and improving the anti-interference capability of the circuit.
Furthermore, the multi-path RS-485 communication network also comprises a power supply conversion module which can convert an external power supply into three voltage values of +5V, +3.3V and + 1.9V. The principle is as follows: the +3.3V level can be used as the working level of the DSP digital signal processor, and the +1.9V level can be used as the core working voltage.
Further, the power conversion module comprises a power conversion circuit 1 and a power conversion circuit 2, wherein the power conversion circuit 1 adjusts the voltage of an external power supply to +12V through an LM117EMP chip, and then adjusts the voltage to +5V through an MIC2397A chip; the power conversion circuit 2 converts the +5V voltage into +3.3V and +1.9V through TPS75733 and TPS76801 chips. The principle is as follows: the power conversion circuit comprises a multi-stage power conversion circuit, and can finally convert an external power supply of 1.2V to 37V into three voltage values of +5V, +3.3V and + 1.9V.
Furthermore, 3 paths of the RS-485 communication terminal are respectively an oil quantity display I, an oil quantity display II and a display control computer. The principle is as follows: the multi-channel RS-485 full duplex communication network formed by connecting the communication terminals has simple structure and low cost and can be used for a fuel oil measurement control system.
Furthermore, the multi-path RS-485 communication network also comprises a UART half-duplex interface circuit; one end of the UART half-duplex interface circuit is connected with an SCIB serial communication port of the DSP digital signal processor, and the other end is connected with peripheral equipment such as a non-avionic monitoring processing system and the like through a half-duplex external bus. The UART connection SCIB is used for expanding the function of the communication network of the invention to widen the application range, and the UART connection SCIB is typically used for connecting a non-avionic monitoring processing system, so that the monitoring function can be realized while the communication is realized.
The invention utilizes the DSP digital signal processor to output control signals to control the switching of the multi-channel RS-485 full duplex communication channel, realizes the multi-channel RS-485 full duplex communication by utilizing the single serial port, saves the programmable devices such as FPGA or CPLD and the like required in the prior art, and designs the process of the communication soft core for the programmable devices such as FPGA or CPLD and the like, and has lower cost and simpler software design; the invention shares a serial communication port of the DSP through a plurality of RS-485 communication channels, more effectively utilizes limited hardware resources, and a communication network formed by the selected chips can be used in the temperature range of-60 ℃ to +125 ℃, thus the temperature application range is wider; when the communication function is expanded, the cost of an RS-485 interface chip and a level conversion chip added on hardware is lower, the reliability of the RS-485 interface chip is high, the consistency of the reliability of a plurality of paths of RS-485 interface circuits can be ensured, the structure of software in a DSP chip is simple and convenient to change, bottom layer driving programs among the paths of RS-485 interface circuits are similar or identical, and the change and the transplantation can be conveniently carried out according to specific conditions.
Compared with the prior art, the invention at least has the following beneficial effects: the cost is lower, the expansion and modification cost is lower, the temperature application range is larger, and the transplantation is more convenient.
Drawings
Fig. 1 is a structure diagram of a multi-path RS-485 communication network in the prior art.
Fig. 2 is a structure diagram of a multi-path RS-485 communication network according to the present invention.
Fig. 3 is a schematic circuit diagram of a multi-path RS-485 communication network according to the present invention.
Fig. 4 is a schematic circuit diagram of an RS-485 interface circuit according to the present invention.
Fig. 5 is a schematic circuit diagram of a power conversion circuit 1 according to the present invention.
Fig. 6 is a schematic circuit diagram of a power conversion circuit 2 according to the present invention.
In the figure: the USB interface circuit comprises a U1.DSP chip, an U2. level conversion chip, a U3.RS-485 communication chip and a U4 UART half-duplex interface circuit.
Detailed Description
The invention is further illustrated with reference to the following figures and examples:
example 1, see figure 2:
a multi-channel RS-485 communication network comprises a DSP (digital signal processor), a channel switching control circuit, at least 3 identical and independent RS-485 interface circuits and at least 3 independent RS-485 communication terminals, wherein the RS-485 communication terminals are provided with RS-485 communication interfaces and are consistent with the RS-485 interface circuits in number; the RS-485 communication terminal is connected with the RS-485 interface circuit in a one-to-one manner to form a plurality of communication channels; the RS-485 interface circuit is used for converting a DSP serial interface communication protocol and an RS-485 serial interface communication protocol; the method is characterized in that: the channel switching control circuit is connected between the DSP and the RS-485 interface circuit and is used for realizing level conversion between the DSP and the RS-485 interface circuit and protection of pins of the DSP; the DSP is used for outputting controllable channel selection signals, receiving and sending data information of a plurality of communication channels and configuring and binding information formats of sent contents; the channel selection signal is transmitted to the RS-485 interface circuit after passing through the channel switching control circuit and is used for enabling the RS485 interface circuit; and the RS-485 communication interfaces of the RS-485 communication terminals are connected with the same serial communication port of the DSP digital signal processor through the corresponding RS-485 interface circuit and the channel switching control circuit. The principle is as follows: each RS-485 interface circuit is respectively connected with one RS-485 communication terminal to form one communication channel, all the communication channels are connected to the same serial port of the DSP, and then the RS-485 interface circuit is controlled by enabling signals of the output channel of the DSP, so that the communication and disconnection between the DSP and one RS-485 communication terminal are controlled. The controllable channel selection signal is determined according to a pre-prepared transceiver mechanism of the DSP digital signal processor: namely, when needing to communicate with a certain RS-485 communication terminal, the channel selection signal enabling the RS-485 interface circuit of the path is output to gate the communication channel of the path. Meanwhile, signals between the DSP and the RS-485 interface circuit are subjected to level switching through the channel switching control circuit and are converted into appropriate driving levels. The switching and information exchange of the multi-channel RS-485 communication channels can be realized by utilizing the channel selection signal output by the DSP and assisting the level conversion of the channel switching control circuit, so that the information exchange and sharing with a plurality of peripheral communication terminals can be realized only by configuring a reasonable transceiving mechanism in the DSP, and the communication soft core is not required to be designed and developed by an FPGA chip.
Example 2:
on the basis of the above embodiment, an embodiment 2 is proposed, which is characterized in that: the RS-485 interface circuit comprises a sending enabling end, a receiving enabling end, a DSP serial port used for being connected with the channel switching control circuit, and an RS-485 full-duplex serial port used for being connected with the RS-485 communication terminal; the DSP serial port comprises two ports, one port is used as a signal input port, and the other port is used as a signal output port; the RS-485 full-duplex serial port comprises 4 ports, wherein two ports are used as differential signal input ports, and the other two pairs are used as differential signal output ports; the transmitting enabling end controls the output of a differential signal output port of the RS-485 full-duplex serial port to be in a high-impedance state or outputs a corresponding value according to the level value of a signal input port of the DSP serial port; and the receiving enabling end controls the DSP serial port output port to be in a high-impedance state or outputs a corresponding value according to the level value of the RS-485 full-duplex serial port differential signal input port. The principle is as follows: in the above mode, the RS-485 interface circuit is an RS-485 full-duplex interface circuit, has 4 ports, can be used for forming an RS-485 full-duplex communication network, can adopt double-end transmission, double-end balanced driving and differential receiving, and is equivalent to two single-end transceivers in each interface circuit, and the balanced driving and differential receiving method can fundamentally eliminate ground wire interference. And the sending and receiving are controlled by the sending enable end and the receiving enable end, and can be controlled by the DSP to be gated.
Example 3, see figure 3:
on the basis of the above embodiment, an embodiment 3 is proposed, which is characterized in that: the DSP digital signal processor is mainly completed by a DSP chip U1, the DSP chip U1 is a TMS320C2000 series chip, and a plurality of I/O ports of the DSP chip U1 are connected with a channel switching control circuit and used for outputting channel selection signals; the channel selection signal is converted into a 5V or 0V level signal by the channel switching control circuit and then transmitted to a transmitting enabling end and a receiving enabling end of the RS-485 interface circuit; the DSP chip U1 contains software for realizing initialization setting of a DSP digital signal processor, control of output level of an I/O port, data information receiving and sending of a multi-channel communication channel and configuration binding of information format of sent content; and the SCIA serial communication port of the DSP chip U1 is connected with the DSP serial ports in all the RS-485 interface circuits after passing through the channel switching control circuit, and is used as a serial communication port finally connected with the RS-485 communication terminal. The TMS320C2000 series DSP chip U1 has two serial communication ports, SCIA and SCIB. SCIA is selected to connect with all DSP serial ports in the RS-485 interface circuit to realize the connection with the multi-path RS-485 communication terminal, and a multi-path communication channel is constructed. The I/O port of the DSP chip U1 can output TTL level according to internal setting, the TTL level can be converted into a 5V or 0V level signal after passing through the channel switching circuit, and the level signal is used for driving a sending enabling end and a receiving enabling end of the RS-485 interface circuit to realize gating and switching of communication channels, and finally realize multi-channel RS-485 full duplex communication according to a required receiving and sending mechanism.
Example 4, see figure 3:
on the basis of the above embodiment, embodiment 4 is proposed, which is characterized in that: the main function of the channel switching control circuit is realized by a level conversion chip U2, and the type of the level conversion chip U2 is selected to be SN74ALVC164245 DL; the A series port of the level conversion chip U2 is connected with the I/O port of the DSP chip U1, and the corresponding B series port is connected with the transmitting enabling end and the receiving enabling end of the RS-485 interface circuit. Specifically, for example, the I/O ports control _1 to control _8 of the DSP chip U1 are used to output channel selection signals, and then the ports control _1 to control _8 are sequentially connected to the ports 1a1 to 1a8 of the level conversion chip U2, and simultaneously the ports 1B1 to 1B8 of the level conversion chip U2 are sequentially connected to the transmit enable terminal and the receive enable terminal of the 4-way RS-485 interface circuit. The principle is as follows: the SN74ALVC164245DL level conversion chip is used, the A series port of the chip is 3.3V standard level, the B series port of the chip is 5.0V standard level, the required level conversion can be realized, and the channel expansion can be realized by selecting a plurality of chips.
Example 5, see fig. 3, 4:
on the basis of the above embodiment, an embodiment 5 is proposed, which is characterized in that: the main functions of the RS-485 interface circuit are realized by an RS-485 communication chip U3, the selection type of the RS-485 communication chip U3 is MAX489ESA, an RO port of the RS-485 communication chip U3 is used as a signal output port of a DSP serial port, a DI port is used as a signal input port of the DSP serial port, and the RS-485 interface circuit is used for being connected with a receiving and transmitting pin of a DSP chip U1SCIA serial port communication port after passing through a channel switching control circuit; an RE port of the RS-485 communication chip U3 is used as a receiving enabling end, and a DE port is used as a sending enabling end; an A port, a B port, a Z port and a Y port of the RS-485 communication chip U3 form an RS-485 full-duplex serial port, wherein the A port and the B port are differential signal input ports, and the Z port and the Y port are differential signal output ports. The principle is as follows: the MAX489ESA is used as a standard RS-485 communication chip U3, has a sending enabling end, a receiving enabling end and an RS-485 full-duplex serial port, can realize conversion of a serial port protocol and has high integration level, and is a preferred scheme for realizing the invention. According to the actual situation, some adaptive resistors can be added in the RS-485 interface circuit, so that the RS-485 communication chip U3 is protected, and the anti-interference capability of the circuit is improved.
Example 6, see fig. 5, 6:
on the basis of the above embodiment, an embodiment 6 is proposed, which is characterized in that: the multi-channel RS-485 communication network also comprises a power supply conversion module which can convert an external power supply into three voltage values of +5V, +3.3V and + 1.9V. The principle is as follows: the +3.3V level can be used as the working level of the DSP digital signal processor, and the +1.9V level can be used as the core working voltage.
Example 7, see fig. 5, 6:
on the basis of the above embodiment, embodiment 7 is proposed, which is characterized in that: the power conversion module comprises a power conversion circuit 1 and a power conversion circuit 2, wherein the power conversion circuit 1 adjusts the voltage of an external power supply to be +12V through an LM117EMP chip, and then adjusts the voltage to be +5V through an MIC2397A chip; the power conversion circuit 2 converts the +5V voltage into +3.3V and +1.9V through TPS75733 and TPS76801 chips. The principle is as follows: the power conversion circuit comprises a multi-stage power conversion circuit, and can finally convert an external power supply of 1.2V to 37V into three voltage values of +5V, +3.3V and + 1.9V.
Example 8:
on the basis of the above embodiment, embodiment 8 is proposed, which is characterized in that: 3 paths of the RS-485 communication terminal are respectively an oil quantity display I, an oil quantity display II and a display control computer. The principle is as follows: the multi-channel RS-485 full duplex communication network formed by connecting the communication terminals has simple structure and low cost and can be used for a fuel oil measurement control system.
Example 9, see fig. 1, 3:
on the basis of the above embodiment, an embodiment 9 is proposed, which is characterized in that: the multi-channel RS-485 communication network also comprises a UART half-duplex interface circuit U4; one end of the UART half-duplex interface circuit U4 is connected with an SCIB serial communication port of the DSP digital signal processor, and the other end is connected with peripheral equipment such as a non-avionic monitoring processing system and the like through a half-duplex external bus. The UART half-duplex interface circuit U4 is connected with SCIB to expand the function of the communication network of the invention, so as to widen the application range, and the UART half-duplex interface circuit U4 is typically used for connecting a non-avionic monitoring processing system, thereby realizing the monitoring function while realizing communication.
Claims (9)
1. A multi-channel RS-485 communication network comprises a DSP (digital signal processor), a channel switching control circuit, at least 3 identical and independent RS-485 interface circuits and at least 3 independent RS-485 communication terminals, wherein the RS-485 communication terminals are provided with RS-485 communication interfaces and are consistent with the RS-485 interface circuits in number; the RS-485 communication terminal is connected with the RS-485 interface circuit in a one-to-one manner to form a plurality of communication channels; the RS-485 interface circuit is used for converting a DSP serial interface communication protocol and an RS-485 serial interface communication protocol; the method is characterized in that: the channel switching control circuit is connected between the DSP and the RS-485 interface circuit and is used for realizing level conversion between the DSP and the RS-485 interface circuit and protection of pins of the DSP; the DSP is used for outputting controllable channel selection signals, receiving and sending data information of a plurality of communication channels and configuring and binding information formats of sent contents; the channel selection signal is transmitted to the RS-485 interface circuit after passing through the channel switching control circuit and is used for enabling the RS485 interface circuit; the RS-485 communication interface of the RS-485 communication terminal is connected with the same serial communication port of the DSP digital signal processor through the corresponding RS-485 interface circuit and the channel switching control circuit, and the RS-485 interface circuit comprises a sending enabling end, a receiving enabling end, a DSP serial port for connecting with the channel switching control circuit and an RS-485 full-duplex serial port for connecting with the RS-485 communication terminal; the DSP serial port comprises two ports, one port is used as a signal input port, and the other port is used as a signal output port; the RS-485 full-duplex serial port comprises 4 ports, wherein two ports are used as differential signal input ports, and the other two pairs are used as differential signal output ports; the transmitting enabling end controls the output of a differential signal output port of the RS-485 full-duplex serial port to be in a high-impedance state or outputs a corresponding value according to the level value of a signal input port of the DSP serial port; and the receiving enabling end controls the DSP serial port output port to be in a high-impedance state or outputs a corresponding value according to the level value of the RS-485 full-duplex serial port differential signal input port.
2. The multi-RS-485 communication network of claim 1, wherein: the DSP digital signal processor function is mainly completed by a DSP chip (U1); the DSP chip (U1) is a TMS320C2000 series chip, and a plurality of I/O ports of the DSP chip are connected with the channel switching control circuit and used for outputting channel selection signals; the channel selection signal is converted into a 5V or 0V level signal by the channel switching control circuit and then transmitted to a transmitting enabling end and a receiving enabling end of the RS-485 interface circuit; the DSP chip (U1) contains software for realizing initialization setting of a DSP digital signal processor, control of output level of an I/O port, data information receiving and sending of a multi-channel communication channel and configuration of information format of binding sending content; and the SCIA serial communication port of the DSP chip (U1) is connected with the DSP serial ports in all the RS-485 interface circuits after passing through the channel switching control circuit, and is used as a serial communication port finally connected with the RS-485 communication terminal.
3. The multi-RS-485 communication network of claim 2, wherein: the main function of the channel switching control circuit is realized by a level conversion chip (U2), and the type of the level conversion chip (U2) is selected to be SN74ALVC164245 DL; the A series port of the level conversion chip (U2) is connected with the I/O port of the DSP chip (U1), and the corresponding B series port is connected with the transmitting enabling end and the receiving enabling end of the RS-485 interface circuit.
4. The multi-RS-485 communication network of claim 3, wherein: the main functions of the RS-485 interface circuit are realized by an RS-485 communication chip (U3), the model selection of the RS-485 communication chip (U3) is MAX489ESA, an RO port of the RS-485 communication chip (U3) is used as a signal output port of a DSP serial port, a DI port is used as a signal input port of the DSP serial port, and the RS-485 interface circuit is used for being connected with a transceiving pin of an SCIA serial port communication port of the DSP chip (U1) after passing through a channel switching control circuit; an RE port of the RS-485 communication chip (U3) is used as a receiving enabling end, and a DE port is used as a sending enabling end; an A port, a B port, a Z port and a Y port of the RS-485 communication chip (U3) form an RS-485 full-duplex serial port, wherein the A port and the B port are differential signal input ports, and the Z port and the Y port are differential signal output ports.
5. The multi-RS-485 communication network according to any of claims 1 to 4, wherein: the multi-channel RS-485 communication network also comprises a power supply conversion module which can convert an external power supply into three voltage values of +5V, +3.3V and + 1.9V.
6. The multi-RS-485 communication network of claim 5, wherein: the power conversion module comprises a power conversion circuit 1 and a power conversion circuit 2, wherein the power conversion circuit 1 adjusts the voltage of an external power supply to be +12V through an LM117EMP chip, and then adjusts the voltage to be +5V through an MIC2397A chip; the power conversion circuit 2 converts the +5V voltage into +3.3V and +1.9V through TPS75733 and TPS76801 chips.
7. The multi-RS-485 communication network according to any of claims 2 to 4, wherein: 3 paths of the RS-485 communication terminal are respectively an oil quantity display I, an oil quantity display II and a display control computer.
8. The multi-RS-485 communication network of claim 6, wherein: 3 paths of the RS-485 communication terminal are respectively an oil quantity display I, an oil quantity display II and a display control computer.
9. The multi-RS-485 communication network of claim 7, wherein: the multi-channel RS-485 communication network also comprises a UART half-duplex interface circuit (U4); and one end of the UART half-duplex interface circuit (U4) is connected with an SCIB serial communication port of the DSP digital signal processor, and the other end is connected with peripheral equipment through a half-duplex external bus.
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| WO2021217309A1 (en) * | 2020-04-26 | 2021-11-04 | 深圳市大疆创新科技有限公司 | Gating circuit, communication circuit, and communication control method and device |
| CN114397832A (en) * | 2021-11-22 | 2022-04-26 | 中国科学院西安光学精密机械研究所 | A serial port multi-computer communication circuit and method |
| CN114301488B (en) * | 2021-12-07 | 2025-06-06 | 贵州航天控制技术有限公司 | RS-485 communication circuit, integrated circuit and electronic device |
| CN114301814A (en) * | 2021-12-10 | 2022-04-08 | 贵州航天凯山石油仪器有限公司 | Method for realizing 485 communication with multiple products based on polling mode |
| CN117558141A (en) * | 2023-11-13 | 2024-02-13 | 广东高信智能科技有限公司 | A traffic identification and control device |
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