Engineering monitor tally

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Joined: 29/09/2016
Posts: 4
Engineering monitor tally

Hi Guys

I've got a setup including three broadcast chains (Ikegami HDK-55 with OCP-300's) and two Hotheads (Panasonic AW-HE130 with two Panasonic RCP's)

So, 5 camera's total with 5 RCP/OCP's, each of which uses contact closure for touchdown preview on the engineering monitor.

That engineering monitor features a nice tally light, that I'd like to get working.

Touchdown preview is working with a Blackmagic GPI interface (we use a BM Router), not the best solution but we manage.

Tally is working with another BM GPI/Tally interface connected to our ATEM 1 M/E.

The thing is, the tally light has to work when the source on the monitor is on PGM. 


I was thinking of using IC's to build a logic circuit, using GPO from both interfaces, using AND gates to check if the source is both on the engineering monitor on the router and in PGM on the switcher, then delivering the result from that gate to an OR gate, and then to the contact closure tally input on the monitor.

Is this a propper way to go? I would combine the GND from both GPI/O units with the GND from the monitor. 

Does anyone have any pointers? Does my idea make sense?


Kind regards!




United Kingdom
Joined: 23/04/2011
Posts: 1217
You can build a combined

You can build a combined touchdown and tally controller using Skaarhoj Arduino libraries - this could work alongside your exisitng solution or it could replace the BMD GPIO interfaces and control your router as well as the tally lights.