How to specify gate and source using QAQmx on LabView 7.0

[mushi]

Probably this has been covered before but I didnt find it on the search.
In the good old days of Traditional DAQ each counter had a gate and a source (well some conters only had a source) can somebody please tell me which vi/property node am I supposed to use to configure the gate and source of each counter?
Currently I am using the M series new card (PCI 6602)

thanks in advance

mushi

Message Edited by mushi on 03-15-2005 01:39 PM

[gus]

It depends on the application you are performing mushi. You can see a list of the different applications and what the GATE, SOURCE, AUX, and OUTPUT are used for in the NI-DAQmx Help->Key NI-DAQmx Concepts->Counters->Counter Parts section. The default connections for a particular applcation can be found in DAQmx Help->Device Considerations->Counter Signal Connections section. Let me know if you have a specific question on changing the defaults for a particular application.

I hope this helps!
gus....

[mushi]

This is a very stupid question, but where exactly do I find this:

NI-DAQmx Help->Key NI-DAQmx Concepts->Counters->Counter

or this

DAQmx Help->Device Considerations->Counter Signal

Is it in the help file, in www.ni.com

I cant seem to find it

thanks in advancee

mushi

[gus]

If you already have DAQmx installed, you can get to the NI-DAQmx Help docuemnt through the start menu at:

Start->Program Files->National Instruments->NI-DAQ->NI-DAQmx Help

This is a help file and the path I gave are the headings on the left panel. If you don't have DAQmx installed, I believe this link is where you can download the latest version of the DAQmx help file from ni.com/manuals.

I hope this helps!
gus....

[mushi]

Thanks again for your prompt replay. I have looked at this help file before but there is somthing basic I dont understand. I am using the M series 6229 and I am trying to setup a counter for counting edges. In all the examples they have both in the web and in the help - find examples there is no CLEAR indication of which vi should I use to specify both the GATE and SOURCE. Is it the DAQmx Channel Property Node is it the DAQmx Trigger property node is it the DAQmx Timing property node is it one of the vi's.

I thought this is somthing pretty basics nothing fancy all I really want to know is how do I tell LabView to take the Gate from say PFI0 and the Source from PFI1. Am I missing somthing?

thanks for all your help anyway

mushi

Message Edited by mushi on 03-16-2005 12:45 PM

[mushi]

I think I have found a way of doing it. I am attaching here the vi that does it, it looks good on the scope so Ill sttle for this for the moment. Thank gus for everything

mushi

[mushi]

When using Traditional DAQ When settying up the Buffer for you had a choice between synchronous and asynchronous counting. The asynchronous counting was offered if your GATE was faster tahn your SOURCE. The problem is I am reading from a device that does not offer a constant rate so somtimes I am counting many edges other times I am counting none. So I need to use asynchronous counting. The vi I posted above with some modifications seems to work fine if the my GATE is slower than my SOURCE what do I do if its the other way round?

any ideas?

mushi

[mushi]

well subject sais it all.

In tradiional DAQ I know how to do Buffered Event Counting how do I do this in DAQmx

[Kevin_Price]

mushi,

Have you looked at the shipping example under Help-->Find Examples...? If you're familiar with counters under traditional NI-DAQ, I suspect the key ingredient you need is to add the DAQmx Timing vi to your config chain. This is how DAQmx distinguishes buffered from unbuffered counting tasks.

Note that in the example, the 'samples per channel' input is left unwired. DAQmx will actually pick a default buffer size to use when performing a continuous acquisition. You *can* override the default, but you need to use a special vi on a lower-level subpalette.

I did a lot of counter programming in traditional NI-DAQ too, and have struggled at times to make the transition over to DAQmx since it's the wave of the future. Some of the things I did were to start tasks then query all kinds of DAQmx properties in a loop to try to get a handle on things. Hang in there, it'll get reasonably familiar before long.

Just one other thing for anyone else listening out there. Is there a way to query the count value when generating a pulse or pulsetrain? I used to be observe the count value decrement toward 0 under traditional NI-DAQ, and found some uses for this info. Under DAQmx, I don't seem to be able to do this.

-Kevin P.

[mushi]

I am playing aroumd with it BUT if you remember in traditional DAQ when you used to use the Counter Buffer (NI-TIO).vi there used to be an option of synchronous and asynchronous counting. This basiclly means that if your GATE is faster than the SOURCE it can still count. When you look at the new examples all work IF your SOURCE is faster tna your GATE so the counter dosnt need to count a zero betwenn two successive gates BUT I need to use asynchronous counting. How do I do this in DAQmx.

---

@Kevin Price wrote:
mushi,

I did a lot of counter programming in traditional NI-DAQ too, and have struggled at times to make the transition over to DAQmx since it's the wave of the future. Some of the things I did were to start tasks then query all kinds of DAQmx properties in a loop to try to get a handle on things. Hang in there, it'll get reasonably familiar before long.

---

Thanks;

Its true I have spoken to the guys at NI and weather we like it or not DAQmx is the future, I suppose once I get the hang of it it will be ok, hopefully

About your question I wish I could help but I have no clues, sorry

mushi