Scan_to_disk replacement function for nidaqmx.h

[sparckis]

Hello,
     We are upgrading an old card to a PCI NI 6224 or 6225.  The old project was developed in C++ and used the nidaq.h header.  The new development will also be done using C++. 

1)  Is there any documentation on how to use the nidaqmx.h file in C++?  If you could point me to it that would be great.

2)  Using C++ as our base, would it be possible to use two 6224 cards instead of the 6225?  Is it still possible to synchronize the cards?

3) I need to replace the old function Scan_to_disk with something that will do the same thing in the nidaqmx driver.  Is this function still realisable?  Is there a procedure out there somewhere?


Thanks

[Alex A.]

Sparckis,

To help answer your questions.....

1)  Is there any documentation on how to use the nidaqmx.h file in C++?  If you could point me to it that would be great.

Using NI-DAQmx in Text Based Programming Environments

For further information about using the functions in the DAQmx API, please refer to the NI-DAQmx C Reference Help located in the Windows start menu:
Start » Programs » National Instruments » NI-DAQ

2)  Using C++ as our base, would it be possible to use two 6224 cards instead of the 6225?  Is it still possible to synchronize the cards?

Yes, you can use two cards in C++, you will just have separate tasks for each as you would in any language.  They can be synchronized by use of a RTSI cable.

3) I need to replace the old function Scan_to_disk with something that will do the same thing in the nidaqmx driver.  Is this function still realisable?  Is there a procedure out there somewhere?

Old Forum on Issue

What are the Terminology Changes in NI-DAQmx?

[sparckis]

Thanks for the help.  Actually, we've decided we can accomplish what we need with just a single card.  We'll try to replace the Scan_to_disk using DAQmxReadAnalogF64 function.  However I'm really lost in the terminology.

What exactly is a 'scan'?  How does a scan work with multiple channels using a scan sequence?

Basically I am working with a device that 'scans' 63 channels using the Scan_to_disk function.

The setup from the original code is 'SCAN_to_Disk(1, 63, Array_of_channel_scan_sequence, Array_of_gains, filename, 151200, 250000.0, 2000, 0)'

Here we setup 63 channels, that are scanned in a sequence defined by the array.  They are then given a gain setting and put into a file.

What I don't understand is how Scans relate to sampleRate (250000.00), ScanRate (2000) .  Also, what does the unit pts/s correspond to in sample rate?

Thanks again.

[sparckis]

Hello,
     I was able to find a helpful link to this issue here
http://forums.ni.com/ni/board/message?board.id=180&message.id=2012&requireLogin=False

Now I am curious though, is it true that NI-Daqmx does not support interval scanning?

http://forums.ni.com/ni/board/message?board.id=250&message.id=26171&requireLogin=False

Thanks again

[Alex A.]

As far as I know, DAQmx is only capable of Round Robin Scanning.

Message Edited by AA_meeting on 09-10-2007 10:55 AM