modbus_reply_exception(3) ========================= NAME ---- modbus_reply_exception - send an exception reponse SYNOPSIS -------- *int modbus_reply_exception(modbus_t *'ctx', const uint8_t *'req', unsigned int 'exception_code'); DESCRIPTION ----------- The *modbus_reply_exception()* function shall send an exception response based on the 'exception_code' in argument. The libmodbus provides the following exception codes: * MODBUS_EXCEPTION_ILLEGAL_FUNCTION (1) * MODBUS_EXCEPTION_ILLEGAL_DATA_ADDRESS (2) * MODBUS_EXCEPTION_ILLEGAL_DATA_VALUE (3) * MODBUS_EXCEPTION_SLAVE_OR_SERVER_FAILURE (4) * MODBUS_EXCEPTION_ACKNOWLEDGE (5) * MODBUS_EXCEPTION_SLAVE_OR_SERVER_BUSY (6) * MODBUS_EXCEPTION_NEGATIVE_ACKNOWLEDGE (7) * MODBUS_EXCEPTION_MEMORY_PARITY (8) * MODBUS_EXCEPTION_NOT_DEFINED (9) * MODBUS_EXCEPTION_GATEWAY_PATH (10) * MODBUS_EXCEPTION_GATEWAY_TARGET (11) The initial request _req_ is required to build a valid response. RETURN VALUE ------------ The function shall return the length of the response sent if successful. Otherwise it shall return -1 and set errno. ERRORS ------ *EINVAL*:: The exception code is invalid SEE ALSO -------- linkmb:modbus_reply[3] linkmb:libmodbus[7] AUTHORS ------- The libmodbus documentation was written by Stéphane Raimbault