While using DAQmx with PXI 4472 Card it is giving an Error 200618

[npai]

i have a PXI 4472 cards, I need some channels for IEPE internal exitation and some with DC coupling. I need to specify those channels.

When I am using DAQmx create channel vi, for different channels, it is givnig me an error -200618

DAQmx Create Channel (AI-Sound Pressure-Microphone).vi:1<append>
<B>Physical Channels: </B>Excitation1

<B>Task Name: </B>_unnamedTask<C>

I am not selecting the channels in a line. I am selecting it randomly. when I do just a single channel in a sequence the programs runs fine, but when i do it random channels it gives me this error.

I am attaching a sample test program with this so u can look at it.

Thanks

Nitin

[Minh T.]

Good afternoon Nitin,

Thanks for contacting National Instruments with your issue, we'll try our best to resolve it for you as quickly and efficiently as possible.

As the error message stated:

"Analog input virtual channels cannot be created out of order with respect to their physical channel numbers for the type of analog device you are using. For example, a virtual channel using physical channel ai0 must be created before a virtual channel with physical channel ai1."

If you need to randomly switch which channels you want to either control IEPE excitation or coupling on, a better approach rather than having all of these channels in one task as you've done in your attached VI, is to parse your program down to multiple tasks that can run simultaneously. 

I have attached a screenshot of this approach, which hopefully is not a compromise to your application.

Best of luck with your project.

Sincerely,

Minh Tran

Applications Engineering

National Instruments

[npai]

Hi Minh,

Thank you for your response.

I tried to do what you suggested to me, but I need to write all the files in a similar file name like ID001_ch1, ID001_ch2 and so on. If I use two parallel tasks for doing AC coupling for some channel # 1,3 ,5 and DC coupling for channel 0,2,4 how will i be able to write them in a sequence. Is there any possible way that I can combine the two task into one

Regards,

Nitin

[Minh T.]

Good afternoon Nitin,

Rather than combining the tasks, which you won't be able to do for your application, you can always merge the signals you're reading which you wish to write to a file.  I have attached VI illustrating the basic concept.  Depending on which version of LabVIEW you're using you can find the Merge Signals.vi in different location, but searcing the function palette should help locate it.

Regards,

Minh Tran

Applications Engineering

National Instruments

[npai]

Good Afternoon Minh,

I tried to merge the two signals, but my problem is little bit different. I have 8 channels so in One of the file name, lets say "ID001" I need to write the signals in the 8 channels with file name "ID001_ch01" "ID001_ch02" and the corresponding signals coming from those channels. As the coupling for different channels is different how will I assign the correct channel name to each of the file if I merge the signals.

I am attaching my VI with this message which will clear what I am saying. I need seperate signal information for each channel in seperate files, not in one file.

Best regards,

Nitin