modbus_rtu_set_custom_rts - set a function to be used for custom RTS implementation
int modbus_rtu_set_custom_rts(modbus_t *ctx, void (*set_rts) (modbus_t *ctx, int on))
The modbus_rtu_set_custom_rts()
function shall set a custom function to be
called when the RTS pin is to be set before and after a transmission. By default
this is set to an internal function that toggles the RTS pin using an ioctl
call.
Note that this function adheres to the RTS mode, the values MODBUS_RTU_RTS_UP
or
MODBUS_RTU_RTS_DOWN
must be used for the function to be called.
This function can only be used with a context using a RTU backend.
The modbus_rtu_set_custom_rts()
function shall return 0 if successful.
Otherwise it shall return -1 and set errno to one of the values defined below.
- EINVAL, the libmodbus backend is not RTU.