Digital triggering problem with PCI-6024E

[ptuinluff]

I believe the PCI-6024E is supposed to support digital triggering. However, I receive the following message whenever I attempt digital triggering:

"Error -200452 occurred at Property Node DAQmx Trigger (arg 1) in DAQmx Start Trigger (Digital Edge).vi:1->trigger test.vi

Possible reason(s):

Measurements: Specified property is not supported by the device or is not applicable to the task.

Property: Start.TrigType

Task Name: _unnamedTask<245>"

 I'm on Labview 8.6 and DAQmx 8.9.

I've included the simple vi I've been trying to test digital triggering with in case I've made any dumb mistakes.

Thanks!

Message Edited by ptuinluff on 05-20-2009 05:26 PM

[Now_With_Underscores]

The Digital output lines on the PCI-6024E are software-timed, so digital triggering is not supported.  Therefore, if you're trying to update DO values on the 6024, this will need to be done in software.  We could have a simple loop that reads the input of your 'trigger' line and then updates the output accordingly.  This will not result in an immediate 'trigger,' as Windows is a nondeterministic operating system; the length of delay is usually very short, but this is not guaranteed due to the nature of the operating system.

If you're trying to start a digital stream with a digital trigger, I would recommend looking at different hardware, such as the PCI-6220, 6251, or any other card that supports hardware-timed DIO.  To browse all cards that support hardware-timed DIO, go to ni.com, click on 'Data Acquisition', click on 'At least 1' under the 'Digital I/O Channels' section, and then click on 'Hardware' under the 'Digital I/O Timing' section.  The resulting cards have hardware-timed DIO, which is what we need to use triggers with DIO.  Since DIO lines on M series devices do not have the necessary hardware to use start triggers, we will need to create a dummy task that does support triggers (AI, Counter, etc). 

Hope this helps.  Let me know if you have any questions.

Regards, 

John S

Applications Engineer

National Instruments 

[ptuinluff]

I see, so I was in fact I was wrong about assuming that PCI-6024E supports digital triggering.

The datasheet seems rather misleading then...

http://www.ni.com/pdf/products/us/4daqsc202-204_ETC_212-213.pdf

What does the mentioned "digital triggering" actually refer to?

In any case, perhaps you could help with an alternative to a hard trigger then:

I'm triggering a camera with a pulse train generated at a counter output and I would like to trigger a task (that turns on one source of illumination) with every other (eg. just even pulses) pulse generated. The other pulses (i.e. the odd pulses) would then trigger another task (that turns on another illumination source).

I would be very grateful for an effective solution that works with the PCI-6024E, thanks!

[ptuinluff]

I've dug around and quite amazingly found a 6251 card!

However, I'm still not sure how to get start triggers working with the M-series card. I don't quite understand what you mean by creating a dummy task that supports triggers.

Thanks!

[Now_With_Underscores]

"Digital Triggering" refers to the fact that we can use digital triggers to start analog tasks.  I agree that this is slightly ambiguous.

John S

Applications Engineer

National Instruments

[Now_With_Underscores · Accepted solution]

Hey Ptuinluff,

 Take a look here for information and an example on how to use another subsystem to enable start triggering.  Let me know if you have any questions.

John S

Applications Engineer

National Instruments 

[ptuinluff]

That works just fine...thanks!