ArduinoRS485 conflict between Serial and Serial1

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1

Hi All
I am attempting implement ArduinoModbus on my STM32 Poternta H7 using the breakout board.

Its well documented that in ArduinoRS485 that the RS485 object is hardwired. If you are using the PH7/Breakout board you need to reconfigure to make sure that the RS485 is set to Serial1/Uart1.

After i have reconfigured, when i run my code i intially can write debug messages to the Serial monitor via Serial (Onboard USB C). But once i start using RS485 on Serial1 i can no longer print to the serial monitor via Serial and the code freezes.

What i did to re configure the RS485 obj. I implemented the following based on this work around from Arduino ArduinoModbus for other shields and with different Serial port - MKR SHIELDS - Arduino Forum
Then saved my updated ArduinoRS485 in /lib.

In ArduinoRS485.cpp

 void RS485Class::setSerial(HardwareSerial* serial) {
  _serial = serial;
}

In ArduinoRS485.h
void setSerial(HardwareSerial* serial);

In my setup code i defined;

 #define UART1_TX_PIN PA_9       // J1 header 33 (LPUART) = SERIAL1_TX  = R0
 #define UART1_RX_PIN PA_10      // J1 header 35 (LPUART) = SERIAL1_RX   = DI
 #define UART1_RTS_PIN PI_14     // J1 header 37 (LPUART) = SERIAL1_RTS  = REn pin
 #define UART1_CTS_PIN PI_15     // J1 header 39 (LPUART) = SERIAL1_CTS  = DE
 #define SERIAL_PORT_HARDWARE Serial1

My ModbusClient set up

void modbusClientSetup() {
     
   while (!Serial);
     Serial.println("");
     Serial.println("Modbus RTU Client Test");
     
     RS485.setPins(UART1_TX_PIN, UART1_RX_PIN, UART1_RTS_PIN);
     RS485.setDelays(50,50);
     RS485.setSerial(&SERIAL_PORT_HARDWARE);
 
     if(!ModbusRTUClient.begin(9600,SERIAL_8N1 )){
     //Serial.println("Failed to start Modbus RTU Client!");
     while (1);
   }
 }

The line Serial.println("Modbus RTU Client Test"); works fine.

Then i run this code to test my Modbus

 void writeCoilValues() {
   
   // set the coils to 1 when counter is odd
   byte coilValue = ((counter % 2) == 0) ? 0x00 : 0x01;
 
   Serial.print("Writing Coil values ... ");
 
   // write 10 Coil values to (slave) id 1, address 0x00
   ModbusRTUClient.beginTransmission(slaveID, COILS, 0x15, 10);>   for (int i = 0; 
     i < 10; i++) {
     counter = i;
     coilValue = ((counter % 2) == 0) ? 0x00 : 0x01;
     ModbusRTUClient.write(coilValue);
     delay(100);
   
   if (!ModbusRTUClient.endTransmission()) {
     Serial.print("failed! ");
     errClient = ModbusRTUClient.lastError();
     Serial.println(errClient);
   } else {
     errClient = "All Good";
     Serial.println("success");
   }
 }

The line Serial.print("Writing Coil values ... "); does not print but the code does not freeze.

But once i get to Serial.print("failed! "); the code just freezes at write_op.wait(NULL); within USBCDC.cpp below.

 bool USBCDC::send(uint8_t *buffer, uint32_t size)
 {
     lock();
 
     AsyncWrite write_op(this, buffer, size);
     _tx_list.add(&write_op);
 
     unlock();
 
     write_op.wait(NULL);
     return write_op.result;
 }

I have been stepping thru this for the last days, but i still cant find where if fails. if anyone has an idea or a better method please let me know.

Cheers

2

Hi someone on a different site gave me a clue for a different way which i have posted here incase anyone else is intrerested.
I had tried this before but for what ever reason i couldnt get it to work. But this code works fine now.

#include <ArduinoRS485.h>
#include <ArduinoModbus.h>

// Pin defs form STM32H7 Portenta H7 on Breakout Board
#define UART1_TX_PIN PA_9       // J1 header 33 (LPUART) = SERIAL1_TX  = R0
#define UART1_RX_PIN PA_10      // J1 header 35 (LPUART) = SERIAL1_RX   = DI
#define UART1_RTS_PIN PI_14     // J1 header 37 (LPUART) = SERIAL1_RTS  = REn pin
#define UART1_CTS_PIN PI_15     // J1 header 39 (LPUART) = SERIAL1_CTS  = DE

// These next two lines are different.
RS485Class rs485(Serial1, UART1_TX_PIN, UART1_RX_PIN, UART1_RTS_PIN);
ModbusRTUClientClass mbClient(&rs485);

void setup() {
  Serial.begin(115200);

  // start the Modbus RTU client
  if (!mbClient.begin(9600)) {
    Serial.println("Failed to start Modbus RTU Client!");
    while (1);
  }
}

void loop() {
 // access various ModbusRTUClient methods with the mbClient object
}