I have this device with an LED is on when the readout terminal of the LED is +5V. In order to turn the LED off, I need to ground that +5V terminal. I wonder what's the best way to do it with the LabJack U3? Should I use one of the FIO?
Since the ground of the device is not the same ground as the U3's GND terminal, what can I try to accomplish what I want to achieve?