Waveform chart extremely fast in the x axis

[kepham]

Hello, I am getting a horizontal line as the waveform chart is running at fast speeds. Is there a way I can enlarge the scale so that it will display more fine, instead of fast horizontal lines that are difficult to read? In the picture is what I am dealing with... I am using the cRIOMain2 to send data via shared variables to the SingleTunnel2 vi.

 

[kepham]

This would be the intended goal...

 

[Bob_Schor · Accepted solution]

Charts plot as fast as you send data to them.  If you are sampling at 1 kHz, you need to plot 1000 (new) points per second (which is about 20 times faster than you can "see" the data).  You can (a) acquire data at a slower rate, or (b) not plot every point.  There are two "easy" ways to do the latter -- plot every Nth (i.e. 20th) point, or average (say 20 points at a time) and plot the averages.

Bob Schor

[sahsak]

Hi!

But how to do that if I am not using DAQmx?

[GerdW]

Hi sahsak,

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@sahsak wrote:

But how to do that if I am not using DAQmx?

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By implementing "senseful" waits in your loops!

In your "SingleTunnel" VI there are loops:

• without any timing, running as fast as possible
• with a wait of "0" - this might have a reason, but it will mostly not fit with your current implementation…
• with a timing of "2000": your VI will get very unresponsive when there is a loop running for 20s (10 × 2000ms) just to read some locals and to plot some data…

Do you really think it is good coding style to have 4 frontpanel elements next to each other and have them ALL named "Nozzle 8"???

[sahsak]

Hi GerdW,

Thanks for your reply.

I am using wait and even tried a timed loop. Now, this solves the problem of "too fast x-axis change", but I am still not getting similar flow of curves as I get when I use DAQmx (idk how to explain this but when I use DAQmx, I could see the nice variation in temperature with time, whereas now it seems like it shows instantaneous values, like zig-zag). Moreover, I am not able to see all the curves I want in the waveform chart. Here is a part of the block diagram with thermocouple-connected channels.

The Strange thing is (or idk if it is even strange) that when I connect the waveform chart to an individual channel (one channel per waveform chart), I see the curves as I see in DAQmx (sort of).

Do you really think it is good coding style to have 4 frontpanel elements next to each other and have them ALL named "Nozzle 8"???

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I am sorry, I should've clarified. This is not me. I am just having similar issue as the original question.

Thanks.

[GerdW]

Hi sahsak,

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@sahsak wrote:

now it seems like it shows instantaneous values, like zig-zag). Moreover, I am not able to see all the curves I want in the waveform chart. Here is a part of the block diagram with thermocouple-connected channels.

The Strange thing is (or idk if it is even strange) that when I connect the waveform chart to an individual channel (one channel per waveform chart), I see the curves as I see in DAQmx (sort of)

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Do you read the context help sometimes?

Did you read the context help for a chart? It explains clearly which datatypes will result in which kind of plots!

You create a 1D array of your 4 TC values: this will result in one (1) plot, containing the values of all 4 TCs.

When you want 4 plots, one for each TC, then you should use a 2D array or a cluster of 4 elements - as explained in the (context) help!!!

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@sahsak wrote:

I am sorry, I should've clarified. This is not me. I am just having similar issue as the original question.

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Then why did you choose to continue this old thread instead of starting your own thread?

Yes, that's irritating.

Why don't you show your code?