How to graph increase in voltage while storing

[alm111222]

Hi, I am relatively new to LabView and require help. 

I have a pressure sensor that takes readings in Volts and it is connected to a 6009 DAQ. I have used the DAQ assistant and have managed to get the output connected to a gauge that is converted to mmHg. The next step is to have a graph that will continuously plot the increase in pressure to time but also store it at the same time. I am currently using a waveform graph but can only get readings in seconds and it does not continuously graph the increase but rather it just shows the increase/decrease in milliseconds within that second. Any help would be greatly appreciated. Thanks

[GerdW]

Hi alm,

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@alm111222 wrote:

I have used the DAQ assistant and have managed to get the output connected to a gauge that is converted to mmHg.

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Which is fine so far…

(Using simple DAQmx functions instead of the DAQAssistent will make your life easier in the end!)

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@alm111222 wrote:

The next step is to have a graph that will continuously plot the increase in pressure to time but also store it at the same time.

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Do you want to  plot the "increase in pressure to time" as the mathematical derivation of the pressure over time? Or do you want to plot just the pressure (on Y axis) vs. time (on X axis)?

A graph just shows the data which you wire to it, it does not "store" any data! When you want to show a certain amount of data then you need to "store" (aka collect) it on your own…

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@alm111222 wrote:

I am currently using a waveform graph but can only get readings in seconds and it does not continuously graph the increase but rather it just shows the increase/decrease in milliseconds within that second. Any help would be greatly appreciated.

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Now it's the point where YOU should attach your current VI so WE can see what you did and where you failed.

In other words: No code, no help!

[alm111222]

So basically I have built a burst pressure test rig, a sample is clamped and the pressure is gradually increased until the sample bursts. I would like for the pressure to be on the y axis and time on x axis. Ideally I want the graph to show the pressure increasing with respect to time and when the pressure suddenly drops (bursts), the maximum point on the graph is the 'burst pressure' and I need it to record highest pressure.

Here is my VI so WE. thanks for help.

[GerdW]

Hi alm,

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@alm111222 wrote:

So basically I have built a burst pressure test rig, a sample is clamped and the pressure is gradually increased until the sample bursts. I would like for the pressure to be on the y axis and time on x axis. Ideally I want the graph to show the pressure increasing with respect to time and when the pressure suddenly drops (bursts), the maximum point on the graph is the 'burst pressure' and I need it to record highest pressure.

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• When you want to plot signal vs. time then you should learn about using waveforms in LabVIEW. (Keep in mind "waveform" is a special LabVIEW datatype, which includes not just the signal values, but also the acquisition time…)
• To find the maximum of a signal/waveform you need to apply a MinMax function somewhere in your code. Right now there is no such function…

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@alm111222 wrote:

Here is my VI so WE. thanks for help.

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No, there is no VI attached in your message. All we got is an image of a VI, which is something completely different!

Would you attach an image of some text when you want to discuss C or Matlab code?

Would you present an image of your car, when you want to have it repaired at the garage?

As I wrote before:  I recommend to use simple DAQmx functions instead of DAQAssistent ExpressVI and the "evil twin" DDT wires!

[alm111222]

I miss understood you, I think I have attached the file now. Thanks. I am having trouble changing getting the values after 1 seconds and not storing it. I also do not understand what you mean by DAQmx functions.