Change X-axis unit of data inTDMS file

[victor55]

Hi NI Community,

I'm open a data file (TDMS file) and I would like to change the X-axis unit.

Currently, it shows the "# of samples" but I'd like to change it to test time duration with the following equation: T0 + SampleingRate*(sample number)

Please show me how to do.

Thank you for your help!

[Dia791]

Hello Victor,

since you're talking about axis, you're probably in VIEW or REPORT module.

I assume your data channel is NOT a waveform (has also no time-depending info like duration...)

In this case you need a time channel; can create it in:

ANALYSIS --> CHANNEL FUNCTIONS --> GENERATE TIME CHANNEL

There select the time unit (e.g. seconds) and "use number of samples" (this value will be automatically set to the mostly correct one).

Finally drag&drop this time channel as X-channel in your diagram.

[victor55]

Hi Dia791! Thank you for your reply. I tried doing this with DIAdem 2018 and I could not find the "number of samples" in Time Unit. I could be understanding your instructions wrong. 

[Dia791]

Time unit = "second"

Time step = 1

Time Domain specification = not the first possible selectiion, but the second; should be something with "number"

[victor55]

Ah I got it. Here is what I have. The settings makes senses. Is the "Number of values" how many points we expect? If I collected a signal at 1MS/s for 10 seconds, that is 10,000,000 points. Do I put that 10,000,000 there? The Generated time is now on the Y_AXIS when I drag and drop it in my graph. How do I make it X axis? 

[Dia791]

Generally you're on the right way, but.

Think about the result: if you have the test duration of 10 seconds at high sampling rate, it doesn't make sense to set the step to "1 second". Maybe it's better to take microsecond? and the time step to 10, if it fits?..

I guess 1 microsecond should fit in this case 🙂

Just play with it to understand, what do you expect to get.

The number of values/samples must be the same as in your data channel, and the time step must be the same as for data.

When you're happy with yout time channel, just put it to the data channel into your graph.