Time on X axes (Multiple pressure sensors)

[Natig]

Hi everyone,

I can not get time in X axes. X axes maximum show always same number with 'samples to read'

I asked chat gpt and read old forums in ni communty. Based on that I have added an empty array to chart history node of waveform chart and added "build waveform". But this did not worked. 

I just want to see time in x axes, which should run as normal seconds. I changed chart history to 30 because I just need to see what happened in last 30 seconds. 

Also I am not sure about all the sample rate, sample to read, there is also sample per channel in timing vi,  and number of samples per channel in read vi. I just need 2 sample in a second to see in write to measurement file later. 

[GerdW]

Hi Natig,

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@Natig wrote:

I just want to see time in x axes, which should run as normal seconds. I changed chart history to 30 because I just need to see what happened in last 30 seconds. 

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You are using a chart, not a graph…

You can display waveforms in the chart and it will display time on X axis! It would help to get rid of ExpressVIs and DDT wires…

Do you want to see absolute timestamps or relative time intervals?

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@Natig wrote:

Also I am not sure about all the sample rate, sample to read, there is also sample per channel in timing vi,  and number of samples per channel in read vi. I just need 2 sample in a second to see in write to measurement file later. 

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Right now you set a sample rate of 500S/s and read 200 samples. This will need 200/500 s = 0.4s.

Additionally there is a 500ms wait inside the loop - which should be DELETED!

When you need just 2S/s then you should set a samplerate of 2 (instead of 500)…

[Natig]

Hello Sir and all labview folk,

I have removed Express vis and DDTs but still I see high numbers in X axes. I want to have time start from 0 and continue. I have unchecked autoscale as well. 

[GerdW]

Hi natig,

see this:

[Natig]

Hi, I think that is what you meant. But It does not start from 0 still.

[GerdW · Accepted solution]

Hi Natig,

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@Natig wrote:

Hi, I think that is what you meant.

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No, this is not what I suggested…

• Why do you manipulate the t0 of the waveforms from DAQ? I didn't say so…
• Why do you need GetDateTime 3 times in the same loop?
• Why do you subtract the current DateTime even though I suggested to use the timestamp from before the loop?
• Why do you subtract the timestamp from your sample data (aka Y array in the waveforms)??? I manipulated the t0 value in the IPE structure!
• Why do you manipulate the dt value in those waveforms instead of relying on your DAQ driver?