Matrox Iris GT MIL Installation And Technical Reference page 131

3. If routing the signal to the Matrox Iris GT trigger signal, connect the ground of
the breakout board (J20 of the breakout board power source connector) and the
TRIG- wire terminal (J37 on the breakout board's input connector) to the ground
of the third-party device providing the trigger signal.
The TRIG- wire terminal can also be connected to another ground (floating
ground) that is not electrically connected to the ground of your Matrox Iris GT.
This results in your Matrox Iris GT being fully isolated electrically from the
opto-coupled trigger signal (that is, both TRIG_OPTO_IN+ and
TRIG_OPTO_IN-).
Alternatively, turn on output-to-trigger bypass switch 2 (SW6[2]). This grounds
the trigger signal (TRIG_OPTO_IN-).
Routing signals to Matrox Iris GT input signals
Breakout board
J37
Third party device
J20
(Trigger generator)
GND
Breakout board
Trig +
J38
Trig -
J37
J20
GND
Third party
device
(Trigger
generator)
GND
131