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Labview does not memorize whole measurement and DAQ assistant time

Hello all,

 

I am still new to Labview and I created a simple program by using the DAQ Assistant.

It measures the temperature with two RTDs and the Pressure with two full bridge pressure transducers, puts it in a graph which I then export to excel.

Now I have the following two problems:

°° I am not able to let the DAQ assistant do a measurement every two or three seconds.

°° For some reason Labview forgets a part of the measurement which is approx. 25minutes and I cannot figure out why it does that? The data is also missing in the excel sheet.

 

Best Regards

 

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A chart has a fixed size buffer and only keeps the last N points. You can change the history size, but don't overdo it. How about using a graph instead of a chart? Do you know the difference?

 

How are you running this? I don't see a top-level loop. Start with some basic tutorials.

 

(Posting by phone, can only look at pictures)


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Dear Knight of NI

 

Thank you, I followed a Tutorial on the youtube labview channel. I searched for the diffrence between a graph and a chart. Altough the tutorial using a graph I changed to a chart since I did not see any graphical results when using the graph. 

 

And I removed the Loop which was used in the tutorial and pressed run continuously to recieve the result I wanted. 

 

I just tryed to easiest way to recieve a graph/chart and excel file with measurements of the two RTDs and two Pressure sensors every second or every two seconds. And I started to trial and error to recieve the result I was aiming for.

 

Best regards

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@JanMM wrote:

And I removed the Loop which was used in the tutorial and pressed run continuously to recieve the result I wanted. 

 


"Run continuously" is a debugging tool to quickly test subVIs that don't have a toplevel loop. They are not a valid way to run a VI. (It basically re-runs the VI from scratch whenever the code completes)  A graph will only display the data from the current iteration, so you need to concatenate it yourself if you want to see all data.

 

Of course if you are happy with the current outcome except for the data length, just increase the chart history. It will be a horrible kludge but maybe it's all you need (shudder!) to do a quick measurement and then never use LabVIEW again.

 

You really (really!) need to first learn the basics. Unfortunately I don't have an DAQ installed, so I cannot even look at your express VI configuration. Maybe somebody else can help you.

 

I don't know what youtube videos you studied.


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Hello altenbach

 

My apologies I really tought Labview was a program which was easy to understand and could be used for a quick measurement. I took a while but I now slowly start to understand a bit of Labview. I still have a lot of work but progressing slowly. Most of the answers on the forum are vague and do not show examples.

Based on the library examples I have created two files since I was not able to merge them.

I have a measurement with a NI9237 for two full bridge pressure transducers which now are adapted so it is possible of measuring 1 sample a second by using decimate.

I have a very different measurement for two RTDs which I just took from the example library since and adapted, it was ok for what I need it.

 

I am aware you cannot just copy paste the two together and cannot use them apart since they are two tasks. 

 

when looking at examples pretty similar tasks like RTD and thermistor or pressure and force use simililar timing and so on.. 

But in my case almost everything is different and I do not understand how I can turn them into one task. I have read and tryed to follow a few examples without any result.  

Except for the DAQmx where you define the type of input/output almost everything is different.

 

ps: By taking less samples with the pressure sensors the charts themself now have more than enough memory.

 

Thank you 

 

Best regards

 

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I don't know if needed but I forgot to attach the files 

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