# modbus_set_debug ## Name modbus_set_debug - set debug flag of the context ## Synopsis ```c int modbus_set_debug(modbus_t *ctx, int flag); ``` ## Description The *modbus_set_debug()* function shall set the debug flag of the *modbus_t* context by using the argument `flag`. By default, the boolean flag is set to `FALSE`. When the `flag` value is set to `TRUE`, many verbose messages are displayed on stdout and stderr. For example, this flag is useful to display the bytes of the Modbus messages. ```text [00][14][00][00][00][06][12][03][00][6B][00][03] Waiting for a confirmation... <00><14><00><00><00><09><12><03><06><02><2B><00><00><00><00> ``` ## Return value The function shall return 0 if successful. Otherwise it shall return -1 and set errno.