The Tally light on the CM70-series (including the NDI camera) is part of the optional license LC70-1 that also includes the Customizable Color Matrix CCM and SRT streaming. Without a license, the LED on the front is not controllable.
There are no status inquiry commands for the Tally light function, but RED, GREEN, OFF commands over VISCA (either IP or serial):
(Cm7x only with license active)
|Red||8x 01 7E 010A 00 02 03 FF||Tally Light Red ON|
|Green||8x 01 7E 010A 00 03 02 FF||Tally Light Green ON|
|Off||8x 01 7E 010A 00 03 03 FF||Tally Light OFF|
* Usually the Tally light is controlled via the video switcher.
* If using a CM70-NDI, don't forget to tick the box "Tally Light Enable":