I wrote a python script acting as a MQTT Client using the standard MySensors Serial Gateway:

https://github.com/arendst/mqtt-mysensors

It is based on the MQTT Ethernet gateway as provided with the MySensors package. It supports the same message structure as
<topic_prefix>/<nodeid>/<childid>/<variable_type> [<value>]

Depending of the presence of <value> a C_SET or C_REQ message is send to the gateway. It recognizes ON and OFF for V_LIGHT. So publishing 'mysensors/0/0/V_LIGHT ON' will turn the light on for node 0 and child 0.

Before use please update the user configuration values according to your environment at the beginning of the script.

@John
Thanks for the response. I use Domoticz as controller which just started to support MySensors. It works great for V_Light and V_Dimmer but lacks RGB color support as the MySensors library lacks color support too.

@hek
Why not update the MySensors library with S_Color and V_RGB. That way Domoticz and other controllers can support color natively.

I agree on the 6 character hex text value. Who will implement this when in 1.4.2?
I have build a RGB neopixel led strip actuator and I would like to control the colours with V_RGB.
Thanks in advance.