I can now use Tuya TS004F rotary knob in a 'dimmer' mode to control a Philips Hue white Zigbee bulb brightness (level control) and switch it on/off, even when my C-7 hub is powered offf ! 
Unfortunately, when the level is changed directly from the dimmer (using the Zigbee Group broadcast), the HE hub does not receive the changed level and the Group DImmer virtual device does not update the level..
Is it possible to also use the Group Messaging for Color Control (0x0300) ?
