connection of grounded signals

[Rupert Lee]

Need: Analog data acquisition. Both main signal (less than 1 V, slowly decaying voltage) and timing signal (5 V DC) have the same ground.

Hardware: PCI-16XE-10 and DAQ AI-16XE-50.

Question: I understand differential input (ACH+ and ACH-) is best. How do I connect the timing signal? PFI0 and DGND? Am I not creating a grouding loop (since DGND and AGND are connected together inside DAQ card)?

[Filipe A.]

Hello;

I'm not sure if I quite understood your question, however, in case you are intending to connect a digital pulse train, to one of the PFI lines, you just connect the digital pulse to the desired PFI line and its GND to the DGND pin, and you should be ok.

Regards
Filipe A.
Applications Engineer
National Instruments