The server does not send an acknowledgment to the client, in case there is a transmission failure or in case a non-existent (or switched off) device is being addressed. This results in a Timeout. When the communication runs over a Modbus RTU/TCP Gateway, you get an error message from this Gateway telling you that the addressed device does not answer.

The server returns the errors with a corresponding error message to the client.

Depending on the error code, ibaPDA reports the error at the start either as error or as warning: