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Thread: CAN-bus to ModbusTCP bridge

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  1. #1
    Junior Member
    Join Date
    May 2022
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    2

    CAN-bus to ModbusTCP bridge

    Hello all, I am new to the Forum and to the Teensy devices.

    I am working on a CAN-ModbusTCP bridge, with a Teensy 4.1 and native PHY Ethernet.

    Currently, I have this project working good with an Arduino Mega 2560, Ethernet shield W5500 and CAN shield MCP2515. Everything works and I have a cycle time of about 12 ms, which is good but I would like to improve.

    I have ported the code to Teensy, using the libraries QNEthernet and FlexCAN_T4. The Modbus library is the same official one for Arduino "ArduinoModbus".
    On the CAN side, it works flawless. Fast and reliable, using mailboxes and filtering.
    BUT the ModbusTCP side, I have configured it as ModbusTCP server, and another device communicates as a client to it.

    Each time there is a package received (especially when the external device writes holding registers), it delays a lot, making the whole thing unusable.
    I have tried both NativeEthernet and QNEthernet libraries. The latter works better but still delays the communication.

    This is the main part of the code. Please note MTCP_zz, MTCP_xx and so on are all very similar.




    Code:
    #include <SPI.h>
    #include <NativeEthernet.h>
    #include <ArduinoRS485.h> // ArduinoModbus depends on the ArduinoRS485 library
    #include <ArduinoModbus.h>
    
    #include <FlexCAN_T4.h>
    FlexCAN_T4<CAN1, RX_SIZE_256, TX_SIZE_16> Can0;
    CAN_message_t msgr;
    
    #define NUM_RX_MAILBOXES 11
    #define NUM_TX_MAILBOXES 3
    
    #define NUMB 10
    
    int16_t  pv[NUMB];
    bool pe[NUMB];
    bool pp[NUMB];
    bool pa[NUMB];
    
    uint8_t mac[] = {
      0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED
    };
    IPAddress ip(10,0,0,20); //bridge IP
    
    EthernetServer ethServer(502);
    
    ModbusTCPServer modbusTCPServer;
    
    unsigned long previousMillis = 0;
    const long interval = 1000;
    
    uint32_t tcicloprev;
    
    const int ledPin = 13;
    
    void setup() {
      pinMode(ledPin, OUTPUT);
      digitalWrite(ledPin, LOW);
      
      Serial.begin(115200);
    
      Ethernet.begin(mac, ip);
      
      // start the server
      ethServer.begin();
    
      if (!modbusTCPServer.begin()) {
        while (1);
      }
    
      modbusTCPServer.configureCoils(0x00, 64);
      modbusTCPServer.configureHoldingRegisters(0x00, 256);
    
      Can0.begin();
      Can0.setBaudRate(250000);
    
      Can0.setMaxMB(NUM_TX_MAILBOXES + NUM_RX_MAILBOXES);
      
      for (int i = 0; i<NUM_RX_MAILBOXES; i++){
        Can0.setMB((FLEXCAN_MAILBOX)i,RX,STD);
      }
      for (int i = NUM_RX_MAILBOXES; i<(NUM_TX_MAILBOXES + NUM_RX_MAILBOXES); i++){
        Can0.setMB((FLEXCAN_MAILBOX)i,TX,STD);
      }
    
      Can0.setMBFilter(REJECT_ALL);
      Can0.enableMBInterrupts();
      
      Can0.onReceive(MB0,canSniff);
      Can0.onReceive(MB1,canSniff);
      Can0.onReceive(MB2,canSniff);
      Can0.onReceive(MB3,canSniff);
      Can0.onReceive(MB4,canSniff);
      Can0.onReceive(MB5,canSniff);
      Can0.onReceive(MB6,canSniff);
      Can0.onReceive(MB7,canSniff);
      Can0.onReceive(MB8,canSniff);
      Can0.onReceive(MB9,canSniff);
      Can0.onReceive(MB10,canSniff);  
      Can0.setMBFilter(MB0,10);
      Can0.setMBFilter(MB1,20);
      Can0.setMBFilter(MB2,30);
      Can0.setMBFilter(MB3,40);
      Can0.setMBFilter(MB4,50);
      Can0.setMBFilter(MB5,60);
      Can0.setMBFilter(MB6,70);
      Can0.setMBFilter(MB7,80);
      Can0.setMBFilter(MB8,90);
      Can0.setMBFilter(MB9,100);
      Can0.setMBFilter(MB10,110);
    
      Can0.mailboxStatus();
    
    }
    
    void canSniff(const CAN_message_t &msg) {
      Serial.print("MB "); Serial.print(msg.mb);
      Serial.print("  OVERRUN: "); Serial.print(msg.flags.overrun);
      Serial.print("  LEN: "); Serial.print(msg.len);
      Serial.print(" EXT: "); Serial.print(msg.flags.extended);
      Serial.print(" TS: "); Serial.print(msg.timestamp);
      Serial.print(" ID: "); Serial.print(msg.id, HEX);
      Serial.print(" Buffer: ");
      for ( uint8_t i = 0; i < msg.len; i++ ) {
        Serial.print(msg.buf[i], HEX); Serial.print(" ");
      } 
      Serial.println();
    
      for (uint8_t i=1; i<NUMB+1; i++){
        
        if (msg.id == (10+(i*10))){
          if (msg.len == 2){
            pp[i] = msg.buf[1];
            pa[i] = msg.buf[0];
          }
          if (msg.len == 3){
            pv[i] = (msg.buf[0]*256) + msg.buf[1];
       
            if (msg.buf[2]==0x20) { pe[i] = true;}
            else { pe[i] = false;}
          }
        }
      }
    }
    
    void loop() {
    
      EthernetClient client = ethServer.available();
    
      if (client) {
        modbusTCPServer.accept(client);
        while (client.connected()) {
          // poll for Modbus TCP requests, while client connected
          modbusTCPServer.poll();
        
          Can0.events();
          MTCP_zz();
          //MTCP_xx();
          //MTCP_yy();
          //MTCP_tt();
        }//END WHILE
        client.stop();
      }//END MODBUS
    
    }
    
    void myCallback() {
      Serial.println("FEED THE DOG SOON, OR RESET!");
    }
    
    
    
    void MTCP_zz(){
    
      uint16_t zz = 0;
    
      CAN_message_t msg;
      
      msg.buf[0]=25;
       
      zz = modbusTCPServer.holdingRegisterRead(0x04);
      if(zz != 0){
        for (int8_t i = 0; i<15; i++){
          
          if (bitRead(zz,i) == 1)
          {
            msg.id = 0x101+(i*10);
            Can0.write(MB12,msg);        
            bitClear(zz,i);
          }
        }
          modbusTCPServer.holdingRegisterWrite(0x04, zz);
      }
    }
    Last edited by FIMC; 05-20-2022 at 08:00 AM. Reason: Clean code and using code tags

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