Detect RS485 disconnection

Official Hardware Pro Solutions Portenta Machine Control
2

Hi @aqw42,

Can you post some sample code. I am working with RS485 modules and I have not come across this problem. I use a the following code to check for errors (using <ArduinoRS485.h> & <ArduinoModbus.h> libraries):

          ModbusRTUClient.beginTransmission(module, HOLDING_REGISTERS, index, 1);
          ModbusRTUClient.write(value);
          if (!ModbusRTUClient.endTransmission()) {
            char buffer[80];
            // Example output: RS485: [M:1 I:02] - Connection timed out
            sprintf(buffer, "RS485: [M:%d I:%02d] - %s", module, index, value, ModbusRTUClient.lastError());
            Serial.println(buffer);
          }

There is a great post here which may be of some use to you: