Using Tally
Sending Tally Signals via a GPI and Tally Interface
Your ATEM switcher can send tally signals to monitors and cameras to make it clear which
source is on the program output, i.e. which source is on air.
Tally is commonly used to light the red light on top of a camera or monitor so the talent knows
they are on air. Tally can also illuminate a border on a monitor such as a Blackmagic SmartView
Duo or SmartView HD. The border allows production staff to know which camera is on air.
The GPI and Tally Interface by Blackmagic Design, is an Ethernet device which provides eight
mechanical relay contact closures to ground that can be used for tally. Tally signals are sent
from the Ethernet port of your ATEM switcher to a GPI and Tally Interface on the same network
as the switcher. By following the wiring guide on the back of the GPI and Tally Interface,
a breakout cable can be connected to video equipment that supports contact closure tally
signals, such as Blackmagic SmartView Duo and SmartView HD. Up to 8 tally receiving devices
can be supported with a single GPI and Tally Interface. Only one GPI and Tally Interface unit is
needed when used with an ATEM switcher that has 1 M/E. Up to 3 units will be needed for the
20 inputs of the ATEM 4 M/E Broadcast Studio 4K and 2 M/E Production Studio 4K.
GPI and Tally Interface
The GPI inputs are optical isolators which are triggered by connection to ground with a
maximum of 5V at 14mA.
The tally outputs are mechanical relay contact closures to ground with a maximum of 30V at 1A.
The following table illustrates which tally signal is sent when a switcher input is selected on the
program output. When using GPI and Tally Interface with an ATEM 2 M/E Production Switcher,
use Blackmagic ATEM Setup to set one unit to signal on tally outputs 1 - 8 and the second unit
to signal on tally outputs 9 - 16.
Program Output
Tally signal
Switcher Input 1
Tally 1
Switcher Input 2
Tally 2
Switcher Input 3
Tally 3
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Using Tally