Turn OFF Tellstick Net/Duo LEDs?

[Safiiri]

TS Net/Duo units have quite powerfull red+blue leds and they lighten a dark room every time when receiving temp measurement from a sensor. You can imagine when there is 10pcs temp sensors and Net/Duo receives data every minute.

Is there any other way to dim or turn Off led than using a black tape? I would appreciate a tdtool command to turn off leds totally and/or dim 80%.