How to connect a BNC to a PFI input (NI USB 6210 DAQ)

[Flonares]

Hello, 

This is a rather n00b question, so please bear with me.

I have a start (+5V)/stop(-5V) trigger created by a laser driver that I wish to feed to my NI USB-6210 in order to create a trigger to start and stop measurements. When it comes to connect a BNC to a AI port, it feels really simple: just wire the two cables coming from the BNC to the positive and negative ends of the the AI channel. My question now is - how about a PFI channel? How do I wire the BNC to the DAQ so that the latter reads a valid TTL sign in a PFI channel? 

Thanks in advance!

  

[santo_13]

Wiring a +/-5V signal into an AI channel is fine, but the signal going into PFI must be a TTL signal and not -5V.

Is your goal to start DAQmx captures/read whenever the signal goes 0 -> +5V and stop the capture whenever the signal goes 0 -> -5V?

[Flonares]

Hello,

That is exactly what I want. I realized that the NI 6210 does not support analog signals, only digital ones.

[santo_13 · Accepted solution]

I would take a post-processing approach.

Connect your LASER trigger signal to another AI channel in addition to your signals to capture, put all these AI channels in the same DAQmx task, and do a continuous high-speed capture.

Create a post-processing algorithm that uses the LASER trigger AI channel voltage level or edge transition to extract the necessary subset of measurement samples.