Is Continuous Digital Buffered Acquisition Possible using PCI-6034E Card?

[Pauldoc]

I am using a PCI-6034E card and I want to continuously acquire and save data from 8 digital input lines.  Furthermore, I only want to read and save the data from the input lines when they change logic level.  Therefore, I thought the 'Cont Change direction vi' from the examples folder would be appropriate for my application.  However, I am receiving error messages when I run the vi due to my interface card not supporting buffered file I/O vi's.  Does this mean that I will not be able to create a vi to perform the function that I want? Or is the some other way of doing this?

I am using Labview 7 Express

cheers  

[JonBowers]

Hi Pauldoc,

The 6034E card is not capable of buffered digital I/O. the example you are talking about is only for the 6534 and the 6533. The example finder should tell you the devices supported in the box in the bottom right hand corner. What speed aquisition are you looking at? if it is fairly slow you could do the change detection in software then decide whether to save it to file or not. However if you need fast aquisition then you would have to purchase a PCI 6533/4.

Regards

Jon B
Applications Engineer
NIUK

[Pauldoc]

Cheers Jon B

Thanks for the help, however I was wondering if you could explain to me what digital I/O functions I can use to change detection as I had the opinion I can only use high level digital I/O.  Would I be correct in saying this?

I am only wanting to acquire approx 1 sample per channel every 5 seconds so I was wondering how I would go about setting a sampling rate?

cheers

Pauldoc    

[Dennis_Knutson]

With your board, the only way to set sampling rate is with software. Look at the shipping example for DAQmx called Read Dig Chan. The loop timing is set for 100msec so the digital channels will be sampled approximately every 100 msec (you can never really depend on timing being exact with just software). To detect a change, all you have to do is wire the current result to a shift register and use the Equal function to compare to the previous value. You can set the Equal function to compare aggregates so that if any bit is different, you will fail the comparison.