64 bit counter

[crdust]

Hi,

we are using PCI 6251 card to acquire some analog signals using a digital trigger.

We are using an external 10MHz GPS clock as the reference clock.

We want to measure the absolute time for each sample based on the GPS signal.

We are thinking of using the 32 bit counter to count the edges of the 10MHz clock, but the counter wraps around in less than 0.5 secs.

Is it possible to use the second counter as an extension to the first and get a 64 bit counter.

Thanks

-Charles

[JoshuaP]

NI is working on a PXI GPS board that will be capable of triggering or timestamping DAQ events to GPS.  It has a direct connection for a GPS antenna or you can use it with an external GPS source.  The board will be similar to the PCI-1588, but in PXI form and it can use GPS, IRIG, a pulse-per-second signal or IEEE 1588 as a time reference.  What is the time frame for your application?

-Josh

[crdust]

Hi,

  we are implementing this right now.

-Charles

[Neal M]

Hello crdust,

Thank you for contacting National Instruments. You can combine the two counters using property nodes so that when the first counter rolls over, it outputs a pulse to the second counter.  You then can compute the total value of the counters, effectively making a 64 bit counter.  I have found an example program that does this in our Developer Zone. I hope this helps you out, if you have any more questions feel free to post back.

Neal M.
NIC AE
www.ni.com/support
SR#: 1041677

[crdust]

Thanks Neal,

we are using LabWindows. It would be helpfull if you could provide some example for LabWindows. Is it possible to convert

the VI to Labwindows code.

Thanks

-Charles

[Neal M]

Hi again Charles,

It is not possible to convert the code from LabVIEW to CVI, however I have rewritten the example for you.  It is pretty simple, but it should give you an idea of how to accomplish what you are trying to do.  I put controls on the UIR so that you can change the device number, however you must still use counter 0 for the primary counter and counter 1 as the rollover counter.  Give this a  try and let me know how it works for you.

Neal M.
NIC AE
www.ni.com/support

[crdust]

Thanks Neal.

-Charles