DAQmx RTSI Counter

Hello All,
I am attempting to generate a 40kHz counter and export the signal to a RTSI channel in order to synchronize two PCI-NIDAQmx cards(6025 & 6259) for analog output signal generation. I have made my best effort to create the VI, but am receiving the following error:
"Labview: Internal Error. Wrong memory zone accessed."
Any assistance would be greatly appreciated, and I'm open to any suggestions or alternate methods!
Sincerely,
Zach
Attachments:
RTSI_Clock.vi ‏29 KB

Hi Zach,
I took a look at your code, and I believe I have the answer as to why you are
receiving this error. It appears that you created a constant for your Simple
Error Handler to specify the "type of dialog", but you accidentally
wired it into the top-most input terminal, which is the "error code"
input. Thus, since you selected "OK message + warnings" on that enum,
it is passing the value of 3 into the error code, and thus returning the error
you are seeing every time you run the VI.
In addition, based on your explanation of what you are trying to accomplish
overall, I am not sure that your code will do quite what you are expecting. You
are using the Export Signal VI to route the Counter Output Event to the RTSI_0
line, but this is not the same as routing the output of the counter. The
Counter Output Event is a signal that will pulse when the counter reaches its
terminal count during an input task. In your case, you would actually want to
connect the counter output line, specified as "Dev1/Ctr0Out" to your
RTSI line using the Connect Terminals VI. You will also then have to disconnect
these terminals at the end of your program before clearing the task. I went
ahead and made the above changes to your VI and have attached it below. Please
also note that DAQmx allows you to route signals over the RTSI bus without
having to manually connect the terminals to the RTSI line. Therefore, you could specify the source of your sample clock on one device to be the counter output of the other device, and as long as you have properly configured the boards in Measurement & Automation Explorer (MAX) to be used with the RTSI cable, it will automatically route the proper signal over the RTSI bus. Hope this helps with your application,
Daniel S.
National Instruments
Attachments:
RTSI_Clock3.vi ‏29 KB

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Attachments:
Counter Output Front Panel Data.png ‏33 KB
Counter Output Block Diagram Data.PNG ‏21 KB
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Traditional DAQ Counter Gate Output.zip ‏32 KB

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Message Edited by Ed W on 01-26-2007 01:50 PM
Message Edited by Ed W on 01-26-2007 01:50 PM
Message Edited by Ed W on 01-26-2007 01:51 PM
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Hi Zibin
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Attachments:
continuously measure period buffered_singlechannel_forum Nov 13.vi ‏33 KB

HI dav2010,
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Try the meathod in the attached VI.
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Ed Dickens - Certified LabVIEW Architect - DISTek Integration, Inc. - NI Certified Alliance Partner
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Clear Counter Timeout.vi ‏35 KB

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I am working on getting just the counter working by using
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Error -200141
occurred at DAQmx Read (Counter DBL 1Chan 1Samp).vi
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Data was overwritten
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Attachments:
Counter_error.jpg ‏45 KB

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Hello every one
please help me with this one i am really stuck.
The situation   : I have two square wave signal, and i want to measure the frequency of both of themat the same time.
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Please see the attachement.
i also have 3 analog inputs to be measured.
but i dont have any problem with the analog inputs,,,multiple analog inputs can easily be measured,,,,,but the prob lem is in the digitl (square wave ) signals.
Attachments:
i want to use two counter input.GIF ‏54 KB
two counter tasks1.vi ‏250 KB

NI has an excellent overview of the accuracy and tradeoffs of the different freq measurement methods titled "Making Accurate Frequency Measurements." To boil down the essence of it, the (possibly) increased accuracy of the 2-counter method depends on a relatively long collection / accumulation time which would in turn typically limit the rate at which you could update your measured freq value.
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What I mean is that just because a hardware freq measurement can be performed that is precise to 1 part per million, it would be very RARE in a test that ALL of those 6 significant digits prove useful. In your app, the measurements are presently only approximately correlated in time. And the gap of blind time between measurements will usually represent a much longer period of time than the measurement itself.
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What would usually work out much better is to sacrifice some accuracy in order to collect a greater quantity of frames. You trade off the instantaneous accuracy for the overall coherency.
Sorry, got on a roll...   Back to your question. My own preference is almost always to avoid consuming hardware resources when not truly necessary. I've been toying with counters for many years and have still never once deployed an app using a 2-counter frequency measurement. I do the 1-counter measurement and save the other counter(s) for other purposes.
If you've got an M-series board, the 80 MHz timebase allows you to measure a 500 kHz pulsetrain with a quantization error of only about 0.06% (1 part in 160). There's a pretty fair chance that whatever physical process emits that pulsetrain isn't appreciably more stable than that
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Custom scale for counter input?

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