I have an industrial camera that I'd like to trigger using code from an Arduino board. The camera has power from another source but can accept a trigger signal through another pin. The documentation states "When configured as inputs, the pins are internally pulled high using weak pull-up resistors to allow easy triggering of the camera by simply shorting the pin to ground (GND)." I've tested this and it does work just fine (there is access to the gnd and trigger pins).
So my question is how can I "short the pin to ground" using an Arduino?
From the description, the camera probably uses a microcontroller itself. Have you A) measured the open circuit voltage across the camera's trigger? And B) the current through the trigger when grounded?
If the answer to A is 5V or less and the answer to B) is 40ma or less, then you can connect the trigger directly to any digital pin of the Arduino and the ground of the Arduino directly to the ground of the camera.