modbus_reply - send a response to the received request
The modbus_reply() function shall send a response to received request. The
req given in argument is analyzed, a response is then built and sent
by using the information of the modbus context
If the request indicates to read or write a value the operation will done in the
mb_mapping according to the type of the manipulated data.
If an error occurs, an exception response will be sent.
This function is designed for Modbus servers.
The function shall return the length of the response sent if successful. Otherwise it shall return -1 and set errno.
- EMBMDATA, sending has failed
See also the errors returned by the syscall used to send the response (eg. send or write).