I try to download the KNX Program to RDG200KN thermostat but When I press the left and right button for 6 second, It blink "PROG" for little bit time and return to normal mode immediately.

So ,I power off the thermostat and on again but It not work.

Hi Pongpakorn,

Maybe the reason is that there is no power supply on the KNX bus.

Please add a bus power supply and try again.

Best regards

RichardF