ModbusMaster: compatibility problem with ESP32?

ModbusMaster version

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About this issue

Original URL
State: closed
Created 6 years ago
Comments: 40

Most upvoted comments

to avoid watchdog timeouts in ESP32 when waiting for a slave response (or when no slave connected), you can disable the watchdog as described above. However this is not ideal. Also when working with multi-thread freeRTOS, the operating system should have the chance to jump to another task when waiting for slave response.

This can be done by inserting a 1ms delay in the transmission loop, it also avoids watchdog timeouts: Since modbus send/receive is slow, I’m using the modbus communication is a seperate freeRTOS task.

in the modbusMaster.ccp file:

// loop until we run out of time or bytes, or an error occurs
  u32StartTime = millis();
  while (u8BytesLeft && !u8MBStatus)
  {
    delay(1);			//WKE to avoid ESP32 watchdog timeout and reset
	if (_serial->available())
    {
#if __MODBUSMASTER_DEBUG__
      digitalWrite(__MODBUSMASTER_DEBUG_PIN_A__, true);
#endif
      u8ModbusADU[u8ModbusADUSize++] = _serial->read();
      u8BytesLeft--;
#if __MODBUSMASTER_DEBUG__
      digitalWrite(__MODBUSMASTER_DEBUG_PIN_A__, false);

TLS1000 on Nov 8, 2019