Help me to organize acquisition from 3 boards PXI-6221, PXI-4472, SCXI-1520

[FFXX]

Hi, experts!

I need to measure signals from three boards (PXI-6221, PXI-4472, SCXI-1520) simultaneously. All signals are different:

6221 – Current (8 channels)

4472 – Accelerometer (4 channels)

1520 – Strain (2 channels)

I created new VI and added three typical measurement DAQmx tasks one after the other. But when I started VI I got next signal from 6221 board (It should be continuous).

 

Other signals seemed to be ok. I think this is a synchronization problem.

How should I organize my VI to get continuous signal?

[FFXX]

I have some information to add.

This is a normal signal (current only measurement):

And I'm attaching a little edited VI

All ideas will be appreciated!

[PeterGC]

FFXX,

Does this behavior start when you add the SCXI task to your program or when you add the 4472?

[FFXX]

This situation appears in the following situations:

1. 6221+4472+1520

2. 6221+4472

[PeterGC]

Try running these two examples individually and if that works, try combining them.  You can slowly add your other functionality once you start collecting proper data.

>>Program Files\National Instruments\LabVIEW 2011\examples\DAQmx\Analog In\Measure Current.llb\Cont Acq 0-20mA Current Samples-Int Clk.vi

>>Program Files\National Instruments\LabVIEW 2011\examples\DAQmx\Analog In\Measure Acceleration.llb\Cont Acq Accel Samples-Int Clk-Analog Start.vi

Let me know how this goes.

[FFXX]

PeterGC, thanks for the answer.  I've found out some interesting thing. Yesterday when I started only acquisition via 6221 board I got the same effect. I tried to figure out what had had the influence to my VI and I realized that nothing had happened except my antivirus system update. I decided to check it via stressing CPU and got the same effect. And now I think that this is a drawing problem. And I don't know how to check it. If you have any suggestions I'll appreciate it very much.

[PeterGC]

Not a problem!

There is not much more to suggest for testing.   You ran some tests and it sounds like it is caused by overloading the system.

I would try slowing down your acquisition speed.  This may allow you to add the other devices and at get some good data, even if it is not as many readings.

Hope this helps,