Protocol Error after connecting to TCPModbus Device

beckseba

Hi all,

the code

if (reply->error() == QModbusDevice::ProtocolError)
{
      qDebug()<<"Write response error: %1 (Mobus exception: 0x%2";
      qDebug()<<reply->errorString();
      qDebug()<<reply->rawResult().exceptionCode();
}

responses with the following error

2021-06-21 14:16:30.750 DBG default: Write response error: %1 (Mobus exception: 0x%2
2021-06-21 14:16:30.750 DBG default: "Modbus Exception Response."
2021-06-21 14:16:30.750 DBG default: 3

after the connection to a TCPModbus coupler is established (connected signal is already triggered). Unfortunately, I cannot find any hint in the documentation on the reason of this error.

Any ideas?

Thanks a lot.