What errors can occur during modbus communication?

Explanation of error codes:

1. The received function code can not be processed.
2. The data address specified in the request is not available.
3. The value contained in the query data field is an invalid value.
4. An unrecoverable error occurred while the slave attempted to perform the requested action.
5. The slave has accepted the request and processes it, but it takes a long time. This response prevents the host from generating a timeout error.
6. The slave is busy processing the command. The master must repeat the message later when the slave is freed.
7. The slave can not execute the program function specified in the request. This code is returned for an unsuccessful program request using functions with numbers 13 or 14. The master must request diagnostic information or error information from the slave.
8. The slave detected a parity error when reading the extended memory. The master can repeat the request, but usually in such cases, repairs are required.