Libraries
9.3 Modbus library instructions
S7-200 SMART
442 System Manual, 09/2015, A5E03822230-AC
Modbus master execution error codes
The high numbered error codes (starting with 101) are errors that are returned by the
Modbus slave device. These errors indicate that the slave does not support the requested
function or that the requested address (either data type or range of addresses) is not
supported by the Modbus slave device.
The low numbered error codes (1 through 12) are errors that are detected by the
MBUS_MSG instruction. These error codes generally indicate a problem with the input
parameters of the MBUS_MSG instruction, or a problem receiving the response from the
slave. Parity and CRC errors indicate that there was a response but that the data was not
received correctly. This is usually caused by an electrical problem such as a bad connection
or electrical noise.
3 Invalid timeout
Signal board port 1 missing or not configured
1 Parity error in response: This is only possible if even or odd parity is used. The
transmission was disturbed and possibly incorrect data was received. This error is
usually caused by an electrical problem such as incorrect wiring or electrical noise
affecting the communication.
3 Receive timeout: There was no response from the slave within the Timeout time.
Some possible causes are bad electrical connections to the slave device, master and
slave are set to a different baud rate / parity setting, and incorrect slave address.
4 Error in request parameter: One or more of the input parameters (Slave, RW, Addr,
or Count) is set to an illegal value. Check the documentation for allowed values for
5 Modbus master not enabled: Call MBUS_CTRL on every scan prior to calling
6 Modbus is busy with another request: Only one MBUS_MSG instruction can be ac-
tive at a time.
7 Error in response: The response received does not correspond to the request. This
indicates some problem in the slave device or that the wrong slave device answered
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