External timing source for Timed Loop/Structure

[mikeeeee]

LabVIEW 8.6 Help file says: "You can create external timing sources for controlling a timed structure. Use the DAQmx Create Timing Source VI to programmatically select an external timing source. You also can use several types of NI-DAQmx timing sources, including frequency, digital edge counters, digital change detection, and signals from task sources, to control timed structures. Use the DAQmx - Data Acquisition VIs to create the following types of NI-DAQmx timing sources to control a timed structure."

I checked "DAQmx Create Timing Source VI" help and it says it can use a frequency timing source from a counter such as PXI-6608 which features an OCXO timebase.

Now my question is: can I use PXI-6653 Timing & Synchronization Module as the frequency timing source for "DAQmx Create Timing Source VI"? If so, how do I use it in software?

[Meadow]

Hello Mikee,

I checked the specification of PXI-6653 that you mentioned and it does have OCXO timebase in the system.

There is an example on using timed loop with Create Timing Source VI that give you an example on how to use the functions. The example is using timeloop with NI-DAQmx: time loop when Digital Input Change Detection and read digital level. The link to the example is:

http://zone.ni.com/devzone/cda/epd/p/id/6165

Let me know if you need a further assistance.

James

[mikeeeee]

Hi. thank you very much for the kind effort. Before I posted this question, I have actually had a look at the example that uses DAQmx to create external timing source (frequency source in particular that can use PXI-6608 counter card).
 
What is not clear is whether PXI-6653 Timing & Synchronization Module can be used as the external timing source. From what I know, PXI-6653 uses NI-Sync instead of DAQmx.

Message Edited by mikeeeee on 06-09-2009 03:06 AM

[Meadow]

Hello Mikee,

I understand what you mean. I found a more suitable example that you can refer to where the example is showing how to use NI-Sync to send sample clock and start trigger to DAQmx Device. I believe that you would need to adjust the example a bit but should worth a try.

Use NI-Sync to Send a Sample Clock and Start Trigger to a DAQmx Device.

http://decibel.ni.com/content/docs/DOC-3421

Regards