*int modbus_reply(modbus_t *ctx, const uint8_t *req, int req_length, modbus_mapping_t *mb_mapping);
The modbus_reply() function shall send a response to received request. The request req given in argument is analyzed, a response is then built and sent by using the information of the modbus context ctx.
If the request indicates to read or write a value the operation will done in the modbus mapping 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 server.
The modbus_reply() function shall return the length of the response sent if successful. Otherwise it shall return -1 and set errno.
Sending has failed
See also the errors returned by the syscall used to send the response (eg. send or write).
The libmodbus documentation was written by StГ©phane Raimbault <firstname.lastname@example.org>