07-12-2019 04:42 AM
Hi, I'm working on measuring temperature against time in labview (of a thermistor). The data comes in as voltage and gets converted to temperature in the subvi. I'm not sure whether I should be using a waveform or XY graph for this. I've attached the block diagram and subvi.
Thanks!
Solved! Go to Solution.
07-12-2019 06:20 AM
Hi ehalpin,
I'm not sure whether I should be using a waveform or XY graph for this.
You should be sure about your requirements!
So what exactly do you want to display?
Waveform graphs are perfect for evenly-sampled data (fixed dt), while XY graphs are nice for data with random X coordinates. (You might also use waveform graphs for non-evenly spaced data when using the waveform datatype…)
Why do you need 2 local variables just to display data in the waveform graph?
07-12-2019 06:26 AM
Hi, thanks for the reply. I need to log a change in temperature over time so the waveform seems like the best option then!
Local variables were left over from something else I had tried out. Would it be better to just remove those?
07-12-2019 06:35 AM
@ehalpin13 wrote:
Local variables were left over from something else I had tried out. Would it be better to just remove those?
YES!
@ehalpin13 wrote:
Hi, thanks for the reply. I need to log a change in temperature over time so the waveform seems like the best option then!
You might want to consider moving the DAQ reading/logging into a parallel loop so it is constantly running and gathering data. You could change your graph into a chart then and make things simpler. You should also make sure your DAQ is set to be continuously running at a set rate (DAQmx Timing VI).
07-12-2019 06:59 AM
If you're looking to add a data points to "waveform" over time, it sounds like job for a Chart.
There's an article here on the difference between Graphs and Charts in LabVIEW.
07-12-2019 11:11 AM
I use X-Y charts 99% of the time even though they are a bit more cumbersome, I like having complete control over how the data is presented.