How to generate a trigger at arbitrary time

[mlars]

Hi All,

I have a digital output card pci 6534 and an analog output card pci 6723. 

I would like to generate a long hardware timed pulse sequence. The 6534 has 32mb on board memory so it is good making a long sequence. The 6723 will run out of memory if started at the same time. Therefore I would like to trigger the 6723 at a later time. The boards are connected with rtsi.

I see 3 ways to do this (the last one I know how to do, but the two first would be more elegant):

1) Generate a digital pulse sequence on the ports (know how to this), then convert a port line to a rtsi line (don't know how to that)?

2) Generate a trigger at arbitrary time on the rtsi lines (don't know how to that)?

3) Go with 1) by physically connecting a port line to a PFI line on the analog card.

[Matt_L]

Hi mlars,

I think the easiest way to do this would be to give the trigger a delay time, since there is actually a property node to do just that.  The property allows you to set both time units and length of delay, as seen in the help file here: http://zone.ni.com/reference/en-XX/help/370469AB-01/daqmxprop/attr1856/.  There's also a quick example of this in LabVIEW here: https://decibel.ni.com/content/docs/DOC-10685.  Hope this is what you were looking for!

[mlars]

Hi Matt,

What would you use as trigger source from the 6534?

Thank you for the answer.

-Lars

[Matt_L]

Well, since you say they are both connected with RTSI, I would use that to send that a digital start trigger from the 6534 (you don't have to use one of the digital outputs to do this).  I realize this is a bit different from the example, as the digital edge start trigger VI is what you will use on the 6723 to pull in that trigger and delay the trigger response by your desired amount of time.

To pass the trigger signal out from the 6534, you can do this by using the DAQmx Export Signal VI to send a start trigger over the same RTSI line that you read in on the 6723.  I've attached a screenshot of what this should be like (where the device name would be your 6534 device, and task reference coming from your DO task).  Give this a shot and see if that does the trick for you.

[mlars · Accepted solution]

I did not find a way to send a trigger at an arbitrary time with the RTSI. Instead I went with solution 3) , and connected digital outputs to the analog card PFI channels.