acquiring signals from multiple boards simultaneously

[LVCoder]

Hi,

I am trying to acquire signal from my NI PXI cards simultaneously but having some trouble to implement that.

Here is my setup:

Hardware setup:

1) NI PXIe-1071 chassis

2) Card - NI PXI 4461 - 2 I/P and 2 O/P

3) Card - NI PXI 4492 - 8 I/P

Below is the Acquisition code that I have written:

The issue is that when I use the I/P channels on the same card(4461 or 4492) then the code runs fine, but if I use the input channels on both cards simulataneously then I get an error message:

"

Error -200106 occurred at DAQmx Read (Analog 1D Wfm NChan NSamp).vi:

Possible reason(s):

Property must have the same value for all channels on this device.

Property: RefClk.Src

"

I have tried setting the Reference clock to "Onboard clock" but I still get the same error.

What should I do to reslove this issue? 

Thanks,

Ritesh

[Bob_Schor]

I'm not familiar with those particular cards, but if you are acquiring a similar number of samples from both cards at identical rates (so that you would expect a DAQmx Read N Samples to take the same time for both), you should be able to simply run the two DAQ systems in parallel, starting them in parallel (do not use a Frame Sequence, which forces them to be sequential).  You can even have a single While loop with both DAQ Reads inside it.

Bob Schor

[LVCoder]

Hey Bob, 

the sequency structure is for starting the Input task before the output task. I need to do it sequentially because I do not want my output task to start before my input task.

I just have 1 "start task" for all the input channels and I am using only 1 "DAQmx Read N Samples" for to receive data from all the input channels.

[LVCoder]

I have posted this same question on the hardware board now. Below is the link:

http://forums.ni.com/t5/Instrument-Control-GPIB-Serial/acquiring-signals-from-multiple-boards-simult...

[Dennis_Knutson]

Moved to http://forums.ni.com/t5/Multifunction-DAQ/acquiring-signals-from-multiple-boards-simultaneously/m-p/... Since instrument control board is not appropriate.