problem reading 9236 Strain guage as a golbal variable

[DangerDave]

Gotcha.  You had mentioned LabVIEW Real Time, so I figured I'd check.  

I ran my own DAQmx Task in MAX with the 9235 and saw expected response to strain.  
However, making a Global Virtual Channel from scratch (or converting from the Task) both saw the expected response to strain as well, so at this point, I haven't been able to reproduce the unresponsive and decreased sampling rate behavior in MAX.

Have you tried going back to making a Global Virtual Channel again using the 9205 to see if that is still working for you?

Also I am still observing no response from SignalExpress when I try to read my Global Virtual Channel, so I will research the issue a bit more and ask a few colleagues to see if they have any insights.

[DangerDave]

Hi Ron,

I escalated your issue to some colleagues, and I think we figured out what is going on here.  We actually have a support document that discusses this issue:

http://ae.natinst.com/public.nsf/webPreview/01EC4D7FB46D40608625790B0070DA33?OpenDocument

This could also explain why you are seeing weird behavior in MAX.  It looks like there is already a CAR filed for the behavior, so you can track if it has been fixed in future updates

Best,

David Randolph

Applications Engineering

National Instruments

www.ni.com/support

[RS1973]

Dear Dave

honestly this is  disappointing , now I have to inform project manager  about this bug 😞 

anyways the link you sent for me can not be opened , would you kindy resend or let me have a .pdf format.

Regards

Ron

[DangerDave]

Hi Ron,

Essentially, the problem is that Global Virtual Channels grab data through On Demand sampling, and do not generate any timing configuration for the acquisition.  DSA devices, however, require timing configuration because they are specialized for measuring frequency content.

Regardless, there may be some options we can explore for moving forward.

For one, is there a reason why you need a real time OS on your cDAQ's controller?  It seems like you are not using it at all in your applications. 

If you were to run Windows instead, you could just be running SignalExpress on the controller itself.  Then there would be no need to use a Global Virtual Channel.  You would simply interface with the hardware directly in SignalExpress.

Alternatively, if you have a USB cDAQ, you could similarly interface directly to the module through your desktop (no Global Virtual Channel required).  

WIth LabVIEW, you could also make an application that interfaces with your controller.

[RS1973]

Dear Dave 

By using windows instead of Real time OS you mean , it is possible to install windows on  cDAQ

And on cDAQ I could install signal express ?

If above understanding is correct would you give a link or document how to install windows on CDaq?

This is very essential for me to be able to use the existing configuration for my measurement .

Regards

Ron

[jcofer]

Hi Ron,

This sounds like it's a pretty complex issue that's specific to your individual setup. It might make more sense to create a Service Request about your question, so that one of the Applications Engineers at National Instruments can work with it more closely. Here's the link to do so: https://sine.ni.com/srm/app/getassistance

Once you create a service request, an engineer will help you determine whether you've chosen the correct hardware and software interfaces to do what you're trying to. Personally, I would choose a different, Windows-based device to do what you're trying to do, if you have the resources to do so.

Jennifer

[DangerDave]

Ron,

Here is a Knowledge Base article that describes that processs:

http://digital.ni.com/public.nsf/allkb/C121B7EB066F078D86256D6A0062E317

You will need an external CD-Drive and your own Windows installation CD.

Please note that the installation and functionality of the installed OS is not guaranteed by National Instruments, but with that being said, the controller is essentially a computer and can be treated as such.  Once Windows installed, you could install the appropriate drivers, NI MAX and SignalExpress on the controller itself, and hook up a keyboard, mouse and monitor.