'Turn on dimmer child device.'

def _turn_on_dimmer(self, **kwargs):

    set_req = self.gateway.const.SetReq
    brightness = self._brightness
    if ((ATTR_BRIGHTNESS not in kwargs) or (kwargs[ATTR_BRIGHTNESS] == self._brightness) or (set_req.V_DIMMER not in self._values)):
        return
    brightness = kwargs[ATTR_BRIGHTNESS]
    percent = round(((100 * brightness) / 255))
    self.gateway.set_child_value(self.node_id, self.child_id, set_req.V_DIMMER, percent)
    if self.gateway.optimistic:
        self._brightness = brightness
        self._values[set_req.V_DIMMER] = percent
        self.schedule_update_ha_state()
