I try to communicate CP341 with modbus rtu slave but the response at the funcion code 05 or 15 is always exception code 04. what kind of error is this?? anybody know ???
Hello,Error code 04 = Slave Device Failure
'An unrecoverable error occured while the server was attempting to perform the requested action'
This error code is not seen often. To analyse what the reason in your case might be, more information on your slave device is needed. One possibility is that you try to write into a write protected area of the slave (I have seen this reaction on a device).
by Kate Smith