question about DAQmx Trigger.vi and trigger property node, when using them to program the DSA card and Timer/Couter card.

[xl]

I used DAQmx VI to program the pxi 4472 and pxi 6602 card so that one does the data acquisition the other generate the pulses. I hope these two card can work at the same time, so I specify in the trigger property node that both of the two card will use the star_stigger riging edge as the digital start trigger source and edge, and it can work. But if I changed the trigger property node into start trigger instance of the DAQmx trigger.vi , and specity the digital source and digital source edge, it doesn't work. In theory, I think both of the two methods can work, why in practice it doesn't??

[reddog]

I suspect it's because you are failing to set the Start->Trigger Type attribute. If you look at the block diagram for the Trigger VI, you will see it's setting three properties, trigger type, trigger source, and trigger edge. If you don't set the trigger type property, it will default to a value of None and no triggering will be performed. This may seem a little odd, but it was designed this way so you can easily reconfigure your task to enable/disable triggering without having to set/reset a whole bunch of attributes.

[xiaolu]

Thank you for your reply. But the problem is I have already set the trigger type into "Start Digital Edge" in the block diagram rather than the default value "None".

[xl]

I did it like the attached pic shows. when using the trigger property node it works while the trigger.vi doesn't.

[chericks1]

Hi xl,

Please view the following jpg. It shows the composition of the DAQmx Trigger VI. Inside, it IS the trigger property node. Thus, it will perform the same.

Verify you are connecting the task to the DAQmx Trigger VI. In your picture above, there was no connection shown.

Let me know if you have further questions or if this does not resolve your issue!

Chad AE
Applications Engineer