PCI-6251 reference analoge edge trigger not work with two channels?

[detech]

Thanks, I think you make it very clear now. I am going to try.

[detech]

I tried what you suggested. I input signals from AO0 and AO1, and used APFI as trigger signals (the same signals from AO0 or AO1). I did get trigger triggered. But the signal acquired is not what it should be. It should be a squar wave last 1 second. I got several sharp spikes.

For checking, I input just one signal AO0 or AO1, and used APFI as trigger channel. Trigger signal is same as AO0 or AO1. Everything is fine. I got what I should got.

Still I have problem for acquire two signals at the same time with reference trigger. I am thinking, this card has so many inputs. It should work with two channs.

Please advice.

Liming

[John_P1]

Hi Liming,

I'm not 100% sure that I follow what you are doing.  Is the following procedure correct?

-Connect AO0 to one of the AI Channels

-Connect AO1 to another AI Channel

-Connect either AO0 or AO1 to APFI0

-Output Square Wave on AO channels

-Use Analog Triggering off of APFI0 to acquire on both AI Channels

If that isn't the case let me know.  Could you post a screenshot of the spikes you are seeing and confirm your connections?

Best Regards,

[detech]

What you said are right on the connection. The above is what I see on the screen. I can not get into the measurement system today. I draw what I see per memerization.

Thank

liming

[John_P1]

Can you please attach your code and a connection diagram when you have the chance.

Best Regards,

[detech]

Here is the program I used for acquiring data from 2 channels with third one APFI as trigger. Please check it.

Liming

[John_P1]

Hi detech,

The connection diagram would be also helpful, as well as a screenshot of how your front panel is configured.  It would be helpful to know the following information:

 

Also, it woudln't hurt to post the screenshot after you've ran the test so we can take a look at the actual signal.

Best Regards,

[detech]

Trigger source: APFI;

Chan : DEV1/AI8;

Chan: DEV1/AI0;

Input config: RSE (which is only one working wright)

[John_P1]

Hi detech,

The code works fine on my system (using APFI0).   This is the result I get:

The AI8 channel I just left unconnected--the sawtooth present is a result of ghosting.

This is how I have it connected:

Could you please provide the same information (screenshots of both the measured signal as well as how you have your signal connected).  I'd like to offer some advice but I don't really have any information to work with at this point.

Best Regards,

[John_P1]

I should add that I did make one change--you had configured an Analog Window Trigger when it sounds like you wanted an Analog Edge Trigger.

Now that I think about it, this might explain the behavior you were seeing.  It was a bit confusing since the labels on your controls corresponded with those that would match up to an Analog Edge trigger.

Anyway, try changing the polymorphic trigger VI as follows:

Best Regards,