Triggering ai/Trigger with ao/StartTrigger

[echu]

I'm trying to trigger the AI to start taking measurement using ao/StartTrigger with PXI-6071E. Software trigger is used for AO. As soon as AO start generating signal, the AI should be triggered and start taking measurement.

I had the same system with older NIDAQmx (downloaded from NI ~6 month ago, I'm not sure the exact version). The had triggering code below and it was working

DAQmxCfgDigEdgeStartTrig(aiTask, "ao/StartTrigger", DAQmx_Val_RisingSlope);

DAQmxDisableStartTrig(aoTask);

Now, I'm using NIDAQmx 8.1.6f0. AI always timed out with the same code. I need to add the code below to connect the ao/StartTrigger and PFI6 explicitly to fix the problem.

DAQmxConnectTerms("/DAQ/ao/StartTrigger", "/DAQ/PFI6", DAQmx_Val_DoNotInvertPolarity);

Is the DAQmxConnectTerms required for the newer version of NIDAQmx?

Thanks

Eric

[Ima U]

Hi Eric,

I checked the device routes in Measurement and Automation Explorer (MAX) and there a direct route between PFI6 and aoStartTrigger.  You would have always needed to make the connection so I am curious to know why it worked before without you making the connection.  I would like to know what version of the DAQmx driver that you were using before.  I would also like to know if you made any changes other than the driver (such as a change of hardware).

[echu]

Ima,

Sorry for the late response. Currently, I'm using DAQmx 8.1.6f0. I have been using DAQmx with PCI & PXI-6071E for the last few years. The same code work for me. The last time I used the same code in a similiar system was Sept 06. I could not find out the exact version of NIDAQmx since the system is at cutsomer site. I always installed the latest version available.

Thanks

Eric

[Ima U]

Hi Eric,

I know it has been a while.  What is the status of your application.  Is it working or do you still have a question.  I would like to be of help if I can.

[beavercreek]

I'm having very similar issues....I was expecting that with the following code I would get two AI loops per AO loop.  As you can see this is not what happens.  Any ideas?  (Using 6723 with 6031E (pci))

PS. Not sure why a connection must be made from ao\starttrigger to pfi6 when the ai/ao multidevice example doesn't show this?

[Dan_K]

Hello beavercreek,

How many loops are you getting through the Analog Input and the Analog Output. If you could post a screenshot of your running VI it would help see exactly what is going on. One thing you could try is to use a DAQmx Write Property Node and change the Regeneration Mode to Do Not Allow Regeneration. This will prevent DAQmx from outputting the same sample more than once.

Message Edited by Dan_K on 11-19-2008 12:49 PM