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modbus_receive_confirmation() modbus_receive_confirmation() Name modbus_receive_confirmation - receive a confirmation request Synopsis int modbus_receive_confirmation(modbus_t *ctx, uint8_t *rsp); Description The modbus_receive_confirmation() function shall receive a request via the socket of the context ctx. This function must be used for debugging purposes because the received response isn't checked against the ini- tial request. This function can be used to receive request not handled by the library. The maximum size of the response depends on the used backend, in RTU the rsp array must be MODBUS_RTU_MAX_ADU_LENGTH bytes and in TCP it must be MODBUS_TCP_MAX_ADU_LENGTH bytes. If you want to write code com- patible with both, you can use the constant MODBUS_MAX_ADU_LENGTH (max- imum value of all libmodbus backends). Take care to allocate enough memory to store responses to avoid crashes of your server. Return value The function shall store the confirmation request in rsp and return the response length if successful. The returned request length can be zero if the indication request is ignored (eg. a query for another slave in RTU mode). Otherwise it shall return -1 and set errno. Example uint8_t rsp[MODBUS_MAX_ADU_LENGTH]; rc = modbus_receive_confirmation(ctx, rsp); See also • modbus_send_raw_request <modbus_send_raw_request.md> modbus_receive_confirmation()
Name | Synopsis | Description | Return value | Example | See also
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