simultaneous signals into waveform graph

[CFAMS Brad]

I am trying to use a VI to test multiple components' voltage inputs and outputs and I have developed the following VI.  The problem I am seeing is that when I operate two components, the DAQ assistant sends the two signals in series and my waveform graph doesn't plot the two signals simultaneously.  It appears that the graph flickers as it alternates between either of the signals.  Ideally I want to have about 4 components read by this VI, but I have not been satisfied with two yet.  Is there a better way to split these signals?  I have attached the VI, with my latest unsuccessful attempt to split the signal.  Ideally both readings would be going to the graph simultaneously, as different plots.

[nyc_(is_out_of_here)]

You should be able to get all three plots on that Waveform Chart simultaneously.

What you need to do is use the Bundle Cluster element. By default it has 2 inputs, so you will need to another input.

Then wire the voltage values to its input and wire its output to the Waveform Chart.

I've attached an example in LV8 using random numbers. Hope it helps.

[Dennis_Knutson]

One thing you should not do is mix traditional DAQ and DAQmx. Use one or the other. Another thing, if you want to chart all signals acquired by the DAQ Assistant, wire the chart directly to the output and don't use the Split Signals function. Try doing that without any analog output first and you should see all analog inputs acquired at the same time on your chart.

[CFAMS Brad]

Thank you for both replies.  I had to take some time to upgrade to 8.0

I have incorporated the signal splitter and merger, feeding them into the same graph.  If I have the graph on autoscale and I set one input at a different value than the other (say 1+/-0.5 and 7+/-0.5), I will see the graph continuously flicker from a y scale of 0.5-1.5 then to a y scale of 6.5-7.5.  This flicker is apparent even without autoscale because it is arising from the two signals resulting in 2 graphs!  This is what I don't understand - I have merged the signals, but it wants to reproduce another graph everytime it switches between the signal it is reading!  Meanwhile, the numeric indicators give a good readout. 

I still have not tried to change the DAQmx to DAQ.  I will work on this next.

[Dennis_Knutson]

I guess I don't understand what you're doing now. The output of the DAQ Assistant should not be split/merged or anything except wired straight to the graph. And, I didn't mean to get rid of the DAQmx/DAQ Assistant. I meant that you should get rid of the traditional DAQ for your analog output.

[CFAMS Brad]

Thanks for the response Dennis. 

The first problem that I originally wrote about was that the readback from the DAQmx in my VI "flickers" between the two signals, indicating to me that perhaps the signals needed to split and re-merged.  Using the test function of the DAQmx task manager, the data flow smoothly and simultaneously, but in my VI there will always be, for instance, a changing y-axis in a chart if I set the two voltage signals to different values.  Meanwhile, numeric readbacks seem simultaneous, but that is harder to determine.

The second problem (tradition DAQ output and DAQmx input) stems from me reading a post when I first set up that my hardware does not support DAQmx.  It is a PXI-6704.  I checked this in the LabVIEW help files and this seems to have changed in later versions - although I have yet to make it work with only DAQmx.  Whether or not this is related to the first problem remains to be determined.  I have also posted a reply on the old post regarding incompatibility between the PXI6704 and the DAQmx to clarify what version they were using.

Brad

[CFAMS Brad]

I solved the problem by going to all DAQmx outputs and inputs.  The 6704 is working with DAQmx.  I appreciate the tips - there's obviously a lot I have to learn about this.