mixed signal graph: scaling of x-axis

[Vhha1972]

Hi all,

I am writing a simple program in LabVIEW using DAQ assistant reading 4 signals from 4 AI channels. I have samples to read at 125 and freq at 250.

I am trying to display this data on mixed signal graph. However, the x-axis cannot be scaled! I scale it to say show 5 s of data, but I still get ~ 0.5 s of plots. They don't stretch out to 5 s. If I change samples to read to 1000, then the graph stretches out to 2 s but then the system gets slow.

Please see attached. Any help would be much appreciated!

Saif

[GerdW]

Hi Vhha,

I have samples to read at 125 and freq at 250.

Ok, this makes for 125 Samples / 250 Samples/s = 0.5 s. Getting data for 0.5s sounds familiar, or?

If I change samples to read to 1000, then the graph stretches out to 2 s

Same calculation: 1000 / 250/s = 2s…

I scale it to say show 5 s of data, but I still get ~ 0.5 s of plots.

The x axis scaling of the graph has nothing to do with your DAQ part. And a graph only displays the data you provide it in your wire!

Solution: when you want to show more data in your graph you need to provide more data to the graph! Or in other words: collect the data in a buffer (aka array)!

[Vhha1972]

Thank you so much for your guidence  GerdW 🙂

I did somehow manage to get the 5 seconds of data (from all 4 signal) displayed on the mixed signal graph. Alhough I must confess that I may not have used the most optimized method. Did use stacked registers.

Pls. see VI attached.

I also added radio buttons - to choose between various breathing stages (0 to 😎 and to annotate the text file (last column) accordingly.

Now I am looking for a countdown timer on the UI for each stage. But the countdown time for each stage is different. So, when user clicks on say stage 1, I want the timer to show 20 s, 19 s, ... 0 s. Here 0 s shows this stage is over (20 s duration). Next, when I click on stage 2, I want timer to show 45 s, 44 s, ... 0 s (45 s duration).

Is there an easy way to do it? 

Thanks a lot!

Saif