Integrated service digital network and 485 communication circuit

Abstract

The utility model discloses an integrated service digital network and 485 communication circuit which comprises a USB to TTL circuit, a TTL isolation signal circuit, an optional circuit and an RS485 isolation communication circuit. The output end of the USB-to-TTL circuit is connected with the input end of the TTL isolation signal circuit, the input end of the selective matching circuit and the input end of the RS485 isolation communication circuit. The output end of the TTL isolation signal circuit is respectively connected with the input end of the selective matching circuit and the input end of the RS485 isolation communication circuit; the output end of the matching circuit is connected with the input end of the RS485 isolation communication circuit. The USB-to-TTL circuit converts a USB signal into a TTL signal, the TTL isolation signal circuit performs signal isolation, the RS485 isolation communication circuit performs output voltage isolation and realizes 485 communication, the communication between the USB and the integrated services digital network and the 485 communication can be realized, and the TTL isolation signal circuit and the RS485 isolation communication circuit perform isolated output, thereby being safe and reliable.

Description

Technical Field

[0001] The utility model relates to the technical field of communication, in particular to a one-line and 485 communication circuit. Background Art

[0002] At present, the computer peripheral interface has gradually changed from the serial mode to the USB2.0 interface mode, that is, the USB universal serial bus interface. The interface has the characteristics of fast transmission speed, hot plug support and connection of multiple devices, which has great advantages. At present, the main interface used in industrial production is the RS485 interface. The RS485 interface is a communication interface based on the serial port. It adopts differential signal negative logic and has the advantages of long transmission distance, simple implementation and convenient networking. However, many programs in industrial production need to be implemented with the help of computers, so it is necessary to solve the problem of interface docking with computers. Realizing the conversion between USB signals and RS485 signals will bring great convenience to industrial production. To this end, the Chinese utility model patent with authorization announcement number CN207319228U discloses an industrial USB to RS485 signal converter, a DC-DC power supply circuit, a USB to TTL circuit, a 485 to TTL circuit, a signal isolation circuit, a status indication circuit and a filtering and voltage stabilizing circuit; the USB to TTL circuit is located at the USB end, and the 485 to TTL circuit is located at the RS485 end; the signal isolation circuit is respectively connected to the USB to TTL circuit and the 485 to TTL circuit, and the USB to TTL circuit is also connected to the status indication circuit; the DC-DC power supply circuit is respectively connected to the USB to TTL circuit, the 485 to TTL circuit, the signal isolation circuit, the status indication circuit and the filtering and voltage stabilizing circuit; the utility model converts the USB interface with the RS485 interface and complementarily combines the USB signal with the RS485 signal, thereby solving the problem of interface docking between industrial equipment and computers.

[0003] At the same time, when the MCU peripheral hardware interface is insufficient, or even some single-chip microcomputers do not have USART, IIC, SPI and other interfaces, when there is a need for simple communication with other devices or devices, one-line communication can be used. That is, only one transmission line is needed, one party is the sender, and the other party is the receiver, which is called one-line communication. When debugging the existing devices that support one-line communication, professional equipment such as oscilloscopes or logic analyzers are basically used for debugging. They can only determine the relevant test data based on the waveform diagram they see, which has high professional requirements, and the debugging process is cumbersome and not intuitive. For this reason, the Chinese utility model patent with authorization announcement number CN216412145U discloses a one-line to serial port system, including a one-line transceiver module, a main control MCU, a serial port and USB conversion module, and a power supply module connected to the main control MCU and the USB port device respectively; the utility model converts the one-line data into a serial port signal, and can transmit the one-line data to the main control MCU, and then reads and processes it through the main control MCU and transmits it to the serial port and USB conversion module through the serial port, and then uses USB to connect to the external USB port device to read the one-line data.

[0004] However, there is currently a lack of a circuit that can simultaneously implement USB, one-line and 485 communications. Utility Model Content

[0005] The purpose of the utility model is to provide a one-line and 485 communication circuit. The utility model can realize the communication between USB, one-line and 485, and the TTL isolation signal circuit and the RS485 isolation communication circuit are isolated outputs, which has the advantages of safety and reliability.

[0006] The technical solution of the utility model: a one-line and 485 communication circuit, comprising a USB to TTL circuit, a TTL isolation signal circuit, an optional circuit and an RS485 isolation communication circuit; the output end of the USB to TTL circuit is respectively connected to the input end of the TTL isolation signal circuit, the input end of the optional circuit and the input end of the RS485 isolation communication circuit; the output end of the TTL isolation signal circuit is respectively connected to the input end of the optional circuit and the input end of the RS485 isolation communication circuit; the output end of the optional circuit is connected to the input end of the RS485 isolation communication circuit.

[0007] The above-mentioned one-line and 485 communication circuit, the optional circuit includes resistor R14, resistor R16, resistor R19, resistor R21, capacitor C11, diode D1, diode D2, diode D3, TVS protection tube TVS2, TVS protection tube TVS3, fuse F2 and pin P2; one end of the resistor R21 is connected to the voltage source; the other end of the resistor R21 is connected to one end of the fuse F2 and one end of the TVS protection tube TVS2, and the other end of the resistor R21 is connected to the UART / RXD end; the other end of the TVS protection tube TVS2 is grounded; the other end of the fuse F2 is connected to the positive electrode of the diode D2; the negative electrode of the diode D2 is connected to port 1 of the pin P2; port 2 of the pin P2 is connected to port 4 of the pin P2, and port 2 of the pin P2 is connected to the TXD2 end; the pin P Port 3 of pin 2 is connected to one end of TVS protection tube TVS3, and port 3 of pin P2 is connected to TXD3 end; the other end of the TVS protection tube TVS3 is grounded; one end of the resistor R16 is connected to one end of resistor R14, and one end of the resistor R16 is connected to a voltage source; the other end of the resistor R16 is connected to the positive electrode of diode D1, the positive electrode of diode D3 and one end of capacitor C11, and the other end of the resistor R16 is connected to CH340_RXD end; the other end of the capacitor C11 is grounded; the cathode of the diode D1 is connected to the other end of resistor R14, and the cathode of the diode D1 is connected to CH340_RXD_485 end; the cathode of the diode D3 is connected to one end of resistor R19, and the cathode of the diode D3 is connected to CH340_RXD_UART end; the other end of the resistor R19 is connected to a voltage source.

[0008] The aforementioned one-line and 485 communication circuit, the USB to TTL circuit includes a USB interface USB2, a chip U2, a resistor R7, a resistor R8, a capacitor C3, a capacitor C4, a capacitor C7, a capacitor C10 and a crystal oscillator X2; the ACT pin of the chip U2 is grounded; the TXD pin of the chip U2 is connected to the CH340_TXD end; the RXD pin of the chip U2 is connected to the CH340_RXD end; the V3 pin of the chip U2 is connected to one end of the capacitor C3, and the other end of the capacitor C3 is grounded; the UD+ pin of the chip U2 is connected to one end of the resistor R7, and the other end of the resistor R7 is connected to the DP1 pin of the USB interface USB2 and the DP2 pin of the USB interface USB2; the UD- pin of the chip U2 is connected to one end of the resistor R8, and the other end of the resistor R8 is connected to the DN1 pin of the USB interface USB2 and the DN2 pin of the USB interface USB2; the chip The GND pin of chip U2 is grounded; the X1 pin of the chip U2 is connected to pin 3 of the crystal oscillator X2 and one end of the capacitor C7, and the other end of the capacitor C7 is grounded; the X0 pin of the chip U2 is connected to pin 1 of the crystal oscillator X2 and one end of the capacitor C10, and the other end of the capacitor C10 is grounded; pin 2 of the crystal oscillator X2 and pin 4 of the crystal oscillator X2 are both grounded; the VCC pin of the chip U2 is connected to voltage; the TNOW pin of the chip U2 is connected to the RD end; the GND pin of the USB interface USB2 is grounded; the VBUS pin of the USB interface USB2 is connected to one end of the capacitor C4 and the SBU2 pin of the USB interface USB2, and the VBUS pin of the USB interface USB2 is connected to a voltage source; the GND pin of the USB interface USB2 is connected to the other end of the capacitor C4, and the GND pin of the USB interface USB2 is grounded.

[0009] The aforementioned one-line and 485 communication circuit, the TTL isolation signal circuit includes a chip U3, a resistor R9, a resistor R10, a resistor R11, a resistor R12 and a capacitor C1; the VCC1 pin of the chip U3 is connected to one end of the capacitor C1, and the VCC1 pin of the chip U3 is connected to a voltage source; the other end of the capacitor C1 is grounded; the OUTA pin of the chip U3 is connected to one end of the resistor R9; the other end of the resistor R9 is connected to the TXD2 end; the INB pin of the chip U3 is connected to one end of the resistor R11; the other end of the resistor R11 is connected to the UART / RX D terminal; the GND1 pin of the chip U3 is grounded; the VCC2 pin of the chip U3 is connected to one end of the capacitor C5, and the VCC2 pin of the chip U3 is connected to the voltage source; the INA pin of the chip U3 is connected to one end of the resistor R10; the other end of the resistor R10 is connected to the CH340_TXD terminal; the OUTB pin of the chip U3 is connected to one end of the resistor R12; the other end of the resistor R12 is connected to the CH340_RXD_UART terminal; the GND2 pin of the chip U3 is connected to the other end of the capacitor C5, and the GND2 pin of the chip U3 is grounded.

[0010] The aforementioned one-line and 485 communication circuit, the RS485 isolation communication circuit includes a chip U5, a resistor R20, a resistor R24, a resistor R25, a resistor R29, a resistor R39, a resistor R40, a resistor R41, a resistor R42, a resistor R43, a resistor R44, a capacitor C12, a capacitor C17, a capacitor C21, a capacitor C22, a TVS protection tube TVS1 and a TVS protection tube TVS8; the VCC pin of the chip U5 is connected to a voltage source; the GNDA pin of the chip U5 is grounded; the RO pin of the chip U5 is connected to one end of the resistor R24; the other end of the resistor R24 ​​is connected to Connect to CH340_RXD_485 terminal; the RE pin of the chip U5 is connected to one end of the resistor R40, and the RE pin of the chip U5 is connected to the DE pin of the chip U5; the other end of the resistor R40 is connected to the RD terminal; the DI pin of the chip U5 is connected to one end of the resistor R42; the other end of the resistor R42 is connected to the CH340_TXD terminal; the VCCL pin of the chip U5 is connected to one end of the capacitor C22, and the VCCL pin of the chip U5 is connected to the voltage source; the GND1 pin of the chip U5 is connected to the other end of the capacitor C22, and the GND1 pin of the chip U5 is grounded; the chip U The VISO pin of chip U5 is connected to one end of capacitor C12 and one end of capacitor C17, and the VISO pin of chip U5 is connected to a voltage source; the GNDB pin of chip U5 is grounded; the VISOIN pin of chip U5 is connected to one end of capacitor C21; the other end of capacitor C21 is connected to the other end of capacitor C12 and the other end of capacitor C17, and the other end of capacitor C21 is grounded; the B pin of chip U5 is connected to one end of resistor R20, one end of resistor R25 and one end of resistor R39; the other end of resistor R20 is grounded; the other end of resistor R25 is connected to TVS protection tube TVS 1 and one end of the resistor R29; the other end of the TVS protection tube TVS1 is grounded; the other end of the resistor R29 is connected to the 485_B end; the A pin of the chip U5 is connected to the other end of the resistor R39, one end of the resistor R41 and one end of the resistor R44; the other end of the resistor R41 is connected to one end of the resistor R43 and one end of the TVS protection tube TVS8; the other end of the resistor R43 is connected to the 485_A end; the other end of the TVS protection tube TVS8 is grounded; the other end of the resistor R44 is connected to the SEL pin of the chip U5; the GNDB pin of the chip U5 is grounded.

[0011] The aforementioned one-line and 485 communication circuit also includes a tool interface circuit and an indicator light circuit; the input end of the tool interface circuit is respectively connected to the output end of the TTL isolation signal circuit, the output end of the optional circuit and the output end of the RS485 isolation communication circuit; the input end of the indicator light circuit is connected to the output end of the USB to TTL circuit.

[0012] The aforementioned one-line and 485 communication circuit, the tool interface circuit includes sockets J3 and sockets J4; port 1 of the socket J3 is connected to the voltage source; port 2 of the socket J3 is grounded; port 3 of the socket J3 is connected to the TXD3 terminal; port 4 of the socket J3 is connected to the UART / RXD terminal; port 1 of the socket J4 is connected to the UART / RXD terminal; port 2 of the socket J4 is grounded; port 3 of the socket J4 is connected to the 485_A terminal; port 4 of the socket J4 is connected to the 485_B terminal.

[0013] The aforementioned one-line and 485 communication circuit, the indicator light circuit includes a resistor R13, a resistor R18, an LED lamp DQ3 and an LED lamp DQ4; one end of the resistor R13 is connected to one end of the resistor R18, and one end of the resistor R13 is connected to a voltage source; the other end of the resistor R13 is connected to the positive electrode of the LED lamp DQ3; the negative electrode of the LED lamp DQ3 is connected to the CH340_TXD terminal; the other end of the resistor R18 is connected to the positive electrode of the LED lamp DQ4; the negative electrode of the LED lamp DQ4 is connected to the CH340_RXD terminal.

[0014] In the aforementioned one-line and 485 communication circuit, the chip U2 is a conversion chip; the chip U3 is a dual-channel isolation chip; and the chip U5 is a 485 chip.

[0015] Compared with the prior art, the utility model has the following beneficial effects:

[0016] 1. The USB to TTL circuit of the utility model converts USB signals into TTL signals; the TTL isolation signal circuit can perform signal isolation to make the circuit connection safer; the RS485 isolation communication circuit can isolate the output voltage and realize 485 communication; in addition, the optional circuit uses a jumper selection method to select one-line communication or 485 communication; when the pin P2 is jumped to port 1 and port 2, the optional circuit is one-line communication; when the pin P2 is jumped to port 3 and port 4, the optional circuit 300 is 485 communication; the selection of one-line communication or 485 communication can be realized through the optional circuit; the utility model can realize the communication between USB, one-line and 485, and the TTL isolation signal circuit and the RS485 isolation communication circuit are isolated outputs, which have the advantages of safety and reliability.

[0017] 2. The chip U2 in the USB to TTL circuit of the present invention is connected to the crystal oscillator X2, which can increase the conversion rate of USB signals into TTL signals and achieve high-speed communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a circuit diagram of the utility model;

[0019] Figure 2 This is the circuit diagram of the USB to TTL circuit;

[0020] Figure 3 It is a circuit diagram of a TTL isolation signal circuit;

[0021] Figure 4 It is a circuit diagram of the optional circuit;

[0022] Figure 5 It is the circuit diagram of RS485 isolated communication circuit;

[0023] Figure 6 is a circuit schematic diagram of a tool interface circuit;

[0024] Figure 7 It is a circuit diagram of the indicator light circuit.

[0025] The marks in the attached figure are: 100-USB to TTL circuit, 200-TTL isolation signal circuit, 300-optional circuit, 400-RS485 isolation communication circuit, 500-tool interface circuit, 600-indicator light circuit. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0027] Embodiment: One-line communication and 485 communication circuit, the structure is as follows Figure 1 As shown, it includes a USB to TTL circuit 100, a TTL isolation signal circuit 200, an optional circuit 300 and an RS485 isolation communication circuit 400; the output end of the USB to TTL circuit 100 is respectively connected to the input end of the TTL isolation signal circuit 200, the input end of the optional circuit 300 and the input end of the RS485 isolation communication circuit 400; the output end of the TTL isolation signal circuit 200 is respectively connected to the input end of the optional circuit 300 and the input end of the RS485 isolation communication circuit 400; the output end of the optional circuit 300 is connected to the input end of the RS485 isolation communication circuit 400.

[0028] Optional circuit 300 Figure 4As shown, the optional circuit 300 includes a resistor R14, a resistor R16, a resistor R19, a resistor R21, a capacitor C11, a diode D1, a diode D2, a diode D3, a TVS protection tube TVS2, a TVS protection tube TVS3, a fuse F2 and a pin header P2; one end of the resistor R21 is connected to a voltage source; the other end of the resistor R21 is connected to one end of the fuse F2 and one end of the TVS protection tube TVS2, and the other end of the resistor R21 is connected to a UART / RXD end; the other end of the TVS protection tube TVS2 is grounded; the other end of the fuse F2 is connected to the positive electrode of the diode D2; the negative electrode of the diode D2 is connected to port No. 1 of the pin header P2; port No. 2 of the pin header P2 is connected to port No. 4 of the pin header P2, and port No. 2 of the pin header P2 is connected to the TXD2 end; the No. 3 of the pin header P2 The port is connected to one end of the TVS protection tube TVS3, and the No. 3 port of the pin header P2 is connected to the TXD3 end; the other end of the TVS protection tube TVS3 is grounded; one end of the resistor R16 is connected to one end of the resistor R14, and one end of the resistor R16 is connected to a voltage source; the other end of the resistor R16 is connected to the anode of the diode D1, the anode of the diode D3 and one end of the capacitor C11, and the other end of the resistor R16 is connected to the CH340_RXD end; the other end of the capacitor C11 is grounded; the cathode of the diode D1 is connected to the other end of the resistor R14, and the cathode of the diode D1 is connected to the CH340_RXD_485 end; the cathode of the diode D3 is connected to one end of the resistor R19, and the cathode of the diode D3 is connected to the CH340_RXD_UART end; the other end of the resistor R19 is connected to a voltage source.The optional circuit 300 uses a jumper to select one-line communication or 485 communication; when the pin P2 is jumpered to port 1 and port 2, the optional circuit 300 is one-line communication, at this time the cathode of the diode D2 is connected to the TXD2 terminal, when the TXD2 terminal is the transmitting terminal and sends a high level, the diode D2 is not conducting, the level of the UART / RXD terminal is pulled up to 5V through the resistor R21, at this time the UART / RXD terminal is the receiving terminal and receives a high level; when the TXD2 terminal is the transmitting terminal and sends a high level, the diode D2 is not conducting, and the level of the UART / RXD terminal is pulled up to 5V through the resistor R21, at this time the UART / RXD terminal is the receiving terminal and receives a high level; When the UART / RXD end is the transmitting end and sends a low level, the diode D2 is turned on, and the level of the UART / RXD end is pulled to 0V through the diode D2. At this time, the UART / RXD end is the receiving end and receives a low level; when the UART / RXD end is the transmitting end and sends a low level, the low level signal passes through the chip U3, so that the CH340_RXD_UART end at the back end of the chip U3 is also a low level. At this time, the diode D1 is turned on, and the level of the CH340_RXD end is pulled low. At this time, the receiving end is the CH340_RXD end, and receives a low level; when the UART / RXD end is the transmitting end and sends a high level, the high level signal passes through the chip U3, so that the CH340_RXD_UART end at the back end of the chip U3 is also a high level. At this time, the diode D1 is turned off, and the level of the CH340_RXD end is pulled high by the resistor R16. At this time, the receiving end is the CH340_RXD end, and receives a high level; through the above isolation pull-up mode, one-line bidirectional communication is completed; when the pin P2 jumps When connected to port 3 and port 4, the optional circuit 300 is 485 communication. At this time, the TXD2 terminal is connected to the TXD3 terminal to avoid the interference caused by the one-line communication; when the CH340_TXD terminal sends a high level, the CH340_RXD_485 terminal outputs a high level; when the CH340_RXD_485 terminal receives a low level, the diode D1 is turned on, and the level of the CH340_RXD terminal is pulled down by the diode D1, and the CH340_RXD terminal receives a low level.

[0029] USB to TTL circuit 100 Figure 2As shown, the USB to TTL circuit 100 includes a USB interface USB2, a chip U2, a resistor R7, a resistor R8, a capacitor C3, a capacitor C4, a capacitor C7, a capacitor C10 and a crystal oscillator X2; the ACT pin of the chip U2 is grounded; the TXD pin of the chip U2 is connected to the CH340_TXD end; the RXD pin of the chip U2 is connected to the CH340_RXD end; the V3 pin of the chip U2 is connected to one end of the capacitor C3, and the other end of the capacitor C3 is grounded; the UD+ pin of the chip U2 is connected to one end of the resistor R7, and the other end of the resistor R7 is connected to the DP1 pin of the USB interface USB2 and the DP2 pin of the USB interface USB2; the UD- pin of the chip U2 is connected to one end of the resistor R8, and the other end of the resistor R8 is connected to the DN1 pin of the USB interface USB2 and the DN2 pin of the USB interface USB2; The GND pin is grounded; the X1 pin of the chip U2 is connected to the No. 3 pin of the crystal oscillator X2 and one end of the capacitor C7, and the other end of the capacitor C7 is grounded; the X0 pin of the chip U2 is connected to the No. 1 pin of the crystal oscillator X2 and one end of the capacitor C10, and the other end of the capacitor C10 is grounded; the No. 2 pin of the crystal oscillator X2 and the No. 4 pin of the crystal oscillator X2 are both grounded; the VCC pin of the chip U2 is connected to the voltage; the TNOW pin of the chip U2 is connected to the RD end; the GND pin of the USB interface USB2 is grounded; the VBUS pin of the USB interface USB2 is connected to one end of the capacitor C4 and the SBU2 pin of the USB interface USB2, and the VBUS pin of the USB interface USB2 is connected to the voltage source; the GND pin of the USB interface USB2 is connected to the other end of the capacitor C4, and the GND pin of the USB interface USB2 is grounded.

[0030] TTL isolation signal circuit 200 Figure 3As shown, the TTL isolation signal circuit 200 includes a chip U3, a resistor R9, a resistor R10, a resistor R11, a resistor R12 and a capacitor C1; the chip U3 is a dual-channel isolation chip. The VCC1 pin of the chip U3 is connected to one end of the capacitor C1, and the VCC1 pin of the chip U3 is connected to a voltage source; the other end of the capacitor C1 is grounded; the OUTA pin of the chip U3 is connected to one end of the resistor R9; the other end of the resistor R9 is connected to the TXD2 end; the INB pin of the chip U3 is connected to one end of the resistor R11; the other end of the resistor R11 is connected to the UART / RXD end; the GND1 pin of the chip U3 is grounded; the VCC2 pin of the chip U3 is connected to one end of the capacitor C5, and the VCC2 pin of the chip U3 is connected to a voltage source; the INA pin of the chip U3 is connected to one end of the resistor R10; the other end of the resistor R10 is connected to the CH340_TXD end; the OUTB pin of the chip U3 is connected to one end of the resistor R12; the other end of the resistor R12 is connected to the CH340_RXD_UART end; the GND2 pin of the chip U3 is connected to the other end of the capacitor C5, and the GND2 pin of the chip U3 is grounded. The chip U3 is a dual-channel isolation chip, which can achieve signal isolation of optical communication inside the chip U3, make the circuit connection outside the chip U3 safer, and prevent circuit damage caused by signal level matching errors.

[0031] RS485 isolated communication circuit 400 Figure 5As shown, the RS485 isolation communication circuit 400 includes a chip U5, a resistor R20, a resistor R24, a resistor R25, a resistor R29, a resistor R39, a resistor R40, a resistor R41, a resistor R42, a resistor R43, a resistor R44, a capacitor C12, a capacitor C17, a capacitor C21, a capacitor C22, a TVS protection tube TVS1 and a TVS protection tube TVS8; the chip U5 is a 485 chip. The VCC pin of the chip U5 is connected to a voltage source; the GNDA pin of the chip U5 is grounded; the RO pin of the chip U5 is connected to one end of the resistor R24; the other end of the resistor R24 ​​is connected to the CH340_RXD_485 end; the RE pin of the chip U5 is connected to one end of the resistor R40, and the RE pin of the chip U5 is connected to the DE pin of the chip U5; the other end of the resistor R40 is connected to the RD end; the DI pin of the chip U5 is connected to one end of the resistor R42; the other end of the resistor R42 is connected to the CH340_TXD end; the VCCL pin of the chip U5 is connected to one end of the capacitor C22, and the VCCL pin of the chip U5 is connected to a voltage source; the GND1 pin of the chip U5 is connected to the other end of the capacitor C22, and the GND1 pin of the chip U5 is grounded; the VISO pin of the chip U5 is connected to one end of the capacitor C12 and one end of the capacitor C17, and the VISO pin of the chip U5 is connected to a voltage source; the GNDB pin of the chip U5 is grounded; the V The ISOIN pin is connected to one end of the capacitor C21; the other end of the capacitor C21 is connected to the other end of the capacitor C12 and the other end of the capacitor C17, and the other end of the capacitor C21 is grounded; the B pin of the chip U5 is connected to one end of the resistor R20, one end of the resistor R25 and one end of the resistor R39; the other end of the resistor R20 is grounded; the other end of the resistor R25 is connected to one end of the TVS protection tube TVS1 and one end of the resistor R29; the other end of the TVS protection tube TVS1 is grounded; the other end of the resistor R29 is connected to the 485_B end; the A pin of the chip U5 is connected to the other end of the resistor R39, one end of the resistor R41 and one end of the resistor R44; the other end of the resistor R41 is connected to one end of the resistor R43 and one end of the TVS protection tube TVS8; the other end of the resistor R43 is connected to the 485_A end; the other end of the TVS protection tube TVS8 is grounded; the other end of the resistor R44 is connected to the SEL pin of the chip U5; the GNDB pin of the chip U5 is grounded. The chip U5 is a three-in-one chip for power supply, communication and 485 conversion, which can isolate the output voltage source of 5V. At the same time, the chip U5 can realize 485 communication; the TVS protection tube TVS1 and TVS protection tube TVS8 connected to the chip U5 can play a role of external protection, which can prevent the chip U5 from being damaged due to high-voltage input connected to the external interface.

[0032] It also includes a tool interface circuit 500 and an indicator light circuit 600; the input end of the tool interface circuit 500 is respectively connected to the output end of the TTL isolation signal circuit 200, the output end of the optional circuit 300 and the output end of the RS485 isolation communication circuit 400; the input end of the indicator light circuit 600 is connected to the output end of the USB to TTL circuit 100.

[0033] Tool interface circuit 500 such as Figure 6 As shown, the tool interface circuit 500 includes a socket J3 and a socket J4; port No. 1 of the socket J3 is connected to a voltage source; port No. 2 of the socket J3 is grounded; port No. 3 of the socket J3 is connected to the TXD3 terminal; port No. 4 of the socket J3 is connected to the UART / RXD terminal; port No. 1 of the socket J4 is connected to the UART / RXD terminal; port No. 2 of the socket J4 is grounded; port No. 3 of the socket J4 is connected to the 485_A terminal; and port No. 4 of the socket J4 is connected to the 485_B terminal.

[0034] The indicator light circuit 600 is as follows Figure 7 As shown, the indicator light circuit 600 includes a resistor R13, a resistor R18, an LED lamp DQ3 and an LED lamp DQ4; one end of the resistor R13 is connected to one end of the resistor R18, and one end of the resistor R13 is connected to a voltage source; the other end of the resistor R13 is connected to the positive electrode of the LED lamp DQ3; the negative electrode of the LED lamp DQ3 is connected to the CH340_TXD terminal; the other end of the resistor R18 is connected to the positive electrode of the LED lamp DQ4; the negative electrode of the LED lamp DQ4 is connected to the CH340_RXD terminal.

[0035] Working principle: The USB to TTL circuit 100 of the utility model converts USB signals into TTL signals; the TTL isolation signal circuit 200 can perform signal isolation to make the circuit connection safer; the optional circuit 300 can realize the selection of one-line communication or 485 communication; the RS485 isolation communication circuit 400 can isolate the output voltage and realize 485 communication; in addition, the optional circuit 300 uses a jumper cap to select one-line communication or 485 communication; when the pin P2 jumps to port 1 and port 2, the optional circuit 300 is a one-line communication , at this time, the cathode of diode D2 is connected to TXD2. When TXD2 is the transmitting end and sends a high level, diode D2 is not turned on, and the level of UART / RXD is pulled up to 5V through resistor R21. At this time, UART / RXD is the receiving end and receives a high level; when TXD2 is the transmitting end and sends a low level, diode D2 is turned on, and the level of UART / RXD is pulled to 0V through diode D2. At this time, UART / RXD is the receiving end and receives a low level; when UART / RXD is the transmitting end and sends a low level, the low level signal passes through the core When the UART / RXD terminal is the transmitting terminal and sends a high level, the high level signal passes through the chip U3, making the CH340_RXD_UART terminal at the back end of the chip U3 also high level. At this time, the diode D1 is turned on, and the level of the CH340_RXD terminal is pulled low. At this time, the receiving end is the CH340_RXD terminal, and the low level is received; when the UART / RXD terminal is the transmitting end and sends a high level, the high level signal passes through the chip U3, making the CH340_RXD_UART terminal at the back end of the chip U3 also high level. At this time, the diode D1 is turned off, and the level of the CH340_RXD terminal is pulled high by the resistor R16. At this time, the receiving end is the CH340_RXD terminal, and the Receive high level; through the above isolation pull-up mode, one-line bidirectional communication is completed; when pin P2 is jumped to port 3 and port 4, the optional circuit 300 is 485 communication, at this time TXD2 terminal is connected to TXD3 terminal, which can avoid the interference caused by one-line communication. When CH340_TXD terminal sends high level, CH340_RXD_485 terminal outputs high level; when CH340_RXD_485 terminal receives low level, diode D1 is turned on, at this time the level of CH340_RXD terminal is pulled down by diode D1, and CH340_RXD terminal receives low level.

[0036] The above embodiments only express the implementation methods of the utility model, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the utility model patent. In this embodiment, up, down, left, right, front, and back only represent their relative positions and do not represent their absolute positions. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, which all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model patent shall be based on the attached claims.

Claims

1. A one-line and 485 communication circuit, characterized in that: The invention comprises a USB to TTL circuit (100), a TTL isolation signal circuit (200), an optional circuit (300) and an RS485 isolation communication circuit (400); the output end of the USB to TTL circuit (100) is respectively connected to the input end of the TTL isolation signal circuit (200), the input end of the optional circuit (300) and the input end of the RS485 isolation communication circuit (400); the output end of the TTL isolation signal circuit (200) is respectively connected to the input end of the optional circuit (300) and the input end of the RS485 isolation communication circuit (400); and the output end of the optional circuit (300) is connected to the input end of the RS485 isolation communication circuit (400).

2. The one-line and 485 communication circuit according to claim 1, characterized in that: The matching circuit (300) comprises a resistor R14, a resistor R16, a resistor R19, a resistor R21, a capacitor C11, a diode D1, a diode D2, a diode D3, a TVS protection tube TVS2, a TVS protection tube TVS3, a fuse F2 and a pin header P2; one end of the resistor R21 is connected to a voltage source; the other end of the resistor R21 is connected to one end of the fuse F2 and one end of the TVS protection tube TVS2, and the other end of the resistor R21 is connected to a UART / RXD terminal; the other end of the TVS protection tube TVS2 is grounded; the other end of the fuse F2 is connected to the positive electrode of the diode D2; the negative electrode of the diode D2 is connected to port No. 1 of the pin header P2; port No. 2 of the pin header P2 is connected to port No. 4 of the pin header P2, and port No. 2 of the pin header P2 is connected to the TXD2 terminal; port No. 3 of the pin header P2 The port is connected to one end of the TVS protection tube TVS3, and the No. 3 port of the pin header P2 is connected to the TXD3 end; the other end of the TVS protection tube TVS3 is grounded; one end of the resistor R16 is connected to one end of the resistor R14, and one end of the resistor R16 is connected to a voltage source; the other end of the resistor R16 is connected to the anode of the diode D1, the anode of the diode D3 and one end of the capacitor C11, and the other end of the resistor R16 is connected to the CH340_RXD end; the other end of the capacitor C11 is grounded; the cathode of the diode D1 is connected to the other end of the resistor R14, and the cathode of the diode D1 is connected to the CH340_RXD_485 end; the cathode of the diode D3 is connected to one end of the resistor R19, and the cathode of the diode D3 is connected to the CH340_RXD_UART end; the other end of the resistor R19 is connected to a voltage source.

3. The one-line and 485 communication circuit according to claim 1, characterized in that: The USB to TTL circuit (100) comprises a USB interface USB2, a chip U2, a resistor R7, a resistor R8, a capacitor C3, a capacitor C4, a capacitor C7, a capacitor C10 and a crystal oscillator X2; the ACT pin of the chip U2 is grounded; the TXD pin of the chip U2 is connected to the CH340_TXD terminal; the RXD pin of the chip U2 is connected to the CH340_RXD terminal; the V3 pin of the chip U2 is connected to one end of the capacitor C3, and the other end of the capacitor C3 is grounded; the UD+ pin of the chip U2 is connected to one end of the resistor R7, and the other end of the resistor R7 is connected to the DP1 pin of the USB interface USB2 and the DP2 pin of the USB interface USB2; the UD- pin of the chip U2 is connected to one end of the resistor R8, and the other end of the resistor R8 is connected to the DN1 pin of the USB interface USB2 and the DN2 pin of the USB interface USB2; the G ND pin is grounded; X1 pin of the chip U2 is connected to pin 3 of the crystal oscillator X2 and one end of the capacitor C7, and the other end of the capacitor C7 is grounded; X0 pin of the chip U2 is connected to pin 1 of the crystal oscillator X2 and one end of the capacitor C10, and the other end of the capacitor C10 is grounded; pin 2 of the crystal oscillator X2 and pin 4 of the crystal oscillator X2 are both grounded; the VCC pin of the chip U2 is connected to voltage; the TNOW pin of the chip U2 is connected to the RD end; the GND pin of the USB interface USB2 is grounded; the VBUS pin of the USB interface USB2 is connected to one end of the capacitor C4 and the SBU2 pin of the USB interface USB2, and the VBUS pin of the USB interface USB2 is connected to a voltage source; the GND pin of the USB interface USB2 is connected to the other end of the capacitor C4, and the GND pin of the USB interface USB2 is grounded.

4. The one-line and 485 communication circuit according to claim 3 is characterized in that: The TTL isolation signal circuit (200) comprises a chip U3, a resistor R9, a resistor R10, a resistor R11, a resistor R12 and a capacitor C1; the VCC1 pin of the chip U3 is connected to one end of the capacitor C1, and the VCC1 pin of the chip U3 is connected to a voltage source; the other end of the capacitor C1 is grounded; the OUTA pin of the chip U3 is connected to one end of the resistor R9; the other end of the resistor R9 is connected to the TXD2 end; the INB pin of the chip U3 is connected to one end of the resistor R11; the other end of the resistor R11 is connected to the UART / RXD end; The GND1 pin of chip U3 is grounded; the VCC2 pin of chip U3 is connected to one end of capacitor C5, and the VCC2 pin of chip U3 is connected to a voltage source; the INA pin of chip U3 is connected to one end of resistor R10; the other end of resistor R10 is connected to CH340_TXD end; the OUTB pin of chip U3 is connected to one end of resistor R12; the other end of resistor R12 is connected to CH340_RXD_UART end; the GND2 pin of chip U3 is connected to the other end of capacitor C5, and the GND2 pin of chip U3 is grounded.

5. The one-line and 485 communication circuit according to claim 4, characterized in that: The RS485 isolation communication circuit (400) comprises a chip U5, a resistor R20, a resistor R24, a resistor R25, a resistor R29, a resistor R39, a resistor R40, a resistor R41, a resistor R42, a resistor R43, a resistor R44, a capacitor C12, a capacitor C17, a capacitor C21, a capacitor C22, a TVS protection tube TVS1 and a TVS protection tube TVS8; a VCC pin of the chip U5 is connected to a voltage source; a GNDA pin of the chip U5 is grounded; an RO pin of the chip U5 is connected to one end of the resistor R24; and the other end of the resistor R24 ​​is connected to a CH3 40_RXD_485 terminal; the RE pin of the chip U5 is connected to one end of the resistor R40, and the RE pin of the chip U5 is connected to the DE pin of the chip U5; the other end of the resistor R40 is connected to the RD terminal; the DI pin of the chip U5 is connected to one end of the resistor R42; the other end of the resistor R42 is connected to the CH340_TXD terminal; the VCCL pin of the chip U5 is connected to one end of the capacitor C22, and the VCCL pin of the chip U5 is connected to a voltage source; the GND1 pin of the chip U5 is connected to the other end of the capacitor C22, and the GND1 pin of the chip U5 is grounded; The VISO pin of chip U5 is connected to one end of capacitor C12 and one end of capacitor C17, and the VISO pin of chip U5 is connected to a voltage source; the GNDB pin of chip U5 is grounded; the VISOIN pin of chip U5 is connected to one end of capacitor C21; the other end of capacitor C21 is connected to the other end of capacitor C12 and the other end of capacitor C17, and the other end of capacitor C21 is grounded; the B pin of chip U5 is connected to one end of resistor R20, one end of resistor R25 and one end of resistor R39; the other end of resistor R20 is grounded; the other end of resistor R25 is connected to One end of the TVS protection tube TVS1 and one end of the resistor R29; the other end of the TVS protection tube TVS1 is grounded; the other end of the resistor R29 is connected to the 485_B end; the A pin of the chip U5 is connected to the other end of the resistor R39, one end of the resistor R41 and one end of the resistor R44; the other end of the resistor R41 is connected to one end of the resistor R43 and one end of the TVS protection tube TVS8; the other end of the resistor R43 is connected to the 485_A end; the other end of the TVS protection tube TVS8 is grounded; the other end of the resistor R44 is connected to the SEL pin of the chip U5.

6. The one-line and 485 communication circuit according to claim 1, characterized in that: It also comprises a tool interface circuit (500) and an indicator light circuit (600); the input end of the tool interface circuit (500) is respectively connected to the output end of the TTL isolation signal circuit (200), the output end of the matching circuit (300) and the output end of the RS485 isolation communication circuit (400); the input end of the indicator light circuit (600) is connected to the output end of the USB to TTL circuit (100).

7. The one-line and 485 communication circuit according to claim 6, characterized in that: The tool interface circuit (500) comprises a socket J3 and a socket J4; port No. 1 of the socket J3 is connected to a voltage source; port No. 2 of the socket J3 is grounded; port No. 3 of the socket J3 is connected to a TXD3 terminal; port No. 4 of the socket J3 is connected to a UART / RXD terminal; port No. 1 of the socket J4 is connected to a UART / RXD terminal; port No. 2 of the socket J4 is grounded; port No. 3 of the socket J4 is connected to a 485_A terminal; and port No. 4 of the socket J4 is connected to a 485_B terminal.

8. The one-line and 485 communication circuit according to claim 6, characterized in that: The indicator light circuit (600) comprises a resistor R13, a resistor R18, an LED lamp DQ3 and an LED lamp DQ4; one end of the resistor R13 is connected to one end of the resistor R18, and one end of the resistor R13 is connected to a voltage source; the other end of the resistor R13 is connected to the positive electrode of the LED lamp DQ3; the negative electrode of the LED lamp DQ3 is connected to the CH340_TXD terminal; the other end of the resistor R18 is connected to the positive electrode of the LED lamp DQ4; and the negative electrode of the LED lamp DQ4 is connected to the CH340_RXD terminal.

9. The one-line and 485 communication circuit according to claim 5, characterized in that: The chip U2 is a conversion chip; the chip U3 is a dual-channel isolation chip; and the chip U5 is a 485 chip.

Images