DSC and DAQmx / DAQOPC client not compatible with DAQMX

[Laura F.]

Hi Munir,

I have looked at your pictures and the error is telling us the trouble - that each array for your different channel is a different size (or maybe just one array is a different size).  You can break apart the waveform with the Get Waveform Components function and then use the Array Size function to determine what the array sizes are. 

There are a few techniques that you could use to swap the waveforms to different channels.  The easiest in my opinion is using a case structure to switch the outputs depending on the case.  I've done a really simple example and am attaching it.  You might want to do something a little more complex, with the array operations taking place inside the case structure. 

Hope this helps,

Laura

[mbhatti2000]

Dear Laura,

Thanks once again for the great answers. The stimulation part of my program complete.
Now I want to make a measurement program. I want to ask the following questions:

1) Can the stimulation part and meaurement part work in the same VI?
2) Is there any precautions that should be taken if the stimulation and measurement are done
   at the same time?
3) The measurements will be in the mV range, which example VI would be good for this?
4) I want to measure 8 channels and record them in EDF format, can Labview record in EDF format
   if not which example VI would be good to record the data in ASCII or binary format?

Sincerely,
Munir Afzal Bhatti

[Laura F.]

Hello Munir,

I am glad to hear that you've got part of your program complete!

To answer your questions,

1.  Yes, the stimulation (output) and measurement (input) portions can work in the same VI.  If you are not passing data between the two portions, you could place the code inside separate while loops if necessary.

2.  There are some programming precautions to consider depending on how your VI needs to work.  If you plan to place both the input and output in the same loop be sure to put all of the configuration and start task VIs outside of the loop, as well as any stop and clear task VIs.  You will need to take into account that a DAQmx Read function when doing a continuous operation can take a while to return data depending on your selections.  For example, if you choose a sample rate of 1000 Hz and are reading 5000 samples each iteration, it will take 5 seconds for enough data to be acquired to return.  If you need to update your output waveform during this time, you will have to wait until the next iteration.  I don't think this will be a big problem, you can adjust your samples to read so that it works best for your program, I just want you to think about this.

3. Any example VI will work for measurements in this range.  The important thing is that you set your maximum and minimum values correctly.  For example, you could set the minimum to -100 mV and the maximum to 100 mV so that the driver applies the correct amount of gain to give you the best resolution for your measurement. 

4.  I am not familiar with EDF format and cannot find much information here about it.  However, there are examples of writing to a text file in the example finder such as Write to Text File.vi (search for "text").  If you have further file I/O questions I would recommend starting a new thread in the LabVIEW forum since I am not an expert at it, and I am not sure how many people are looking at this thread. 

Hope this helps!

Laura

[mbhatti2000]

Dear Laura,
I am having problems in saving the waveform information to a file.
When I use the simulated device in  MAX  and choose the channels in it the program works perfectly, But when I open the new project and choose the real time target and add a file such and deploy the VI the to the RT Engine, the VI runs but does not ask where to save the file and the file cannot be saved. I have tried this with all the funtions such as write to measurement file express VI,  write to binary file and write to text file funtions for writing to a file but they do not work after deployment and before deployment using the simulated device they are working and saving the files.