How to Plot Chart in a Desired Speed

[jackhsu66]

Dear Community,

I am currently trying to simulate a pre-recorded signal in LabVIEW. I have successfully plotted the amplitude vs. data points on a chart from the excel file. However, I am having trouble plotting in the speed I want to mimic in real-time. My goal is to plot 1000 data points per second from the excel sheet, however, I'm not sure how to adjust the timing loop to achieve that fast. Also, when I rerun the program, how do I make the x-axis of the chart start from zero again. Thank you in advance!

The files are attached below.

"Read_Signal3.vi" is basically reading data from "20.csv" and plotting the points in a chart.

"20.csv" are the data points recorded with the first column as time and the second column as amplitude to the plot.

[altenbach · Accepted solution]

• What a mess!
• To run at 1000Hz, your wait should be 1ms, not 10ms. (but software timing might not be super deterministic)
• You can remove the header and get the second column as numeric 1D array before the loop, then just autoindex.
• You can write an empty array to the chart history property mode to clear the chart.
• You can show the digital display of the chart, no need for an extra indicator.
• There is no need to get a subset of higher columns (that don't exist!) later in the run.
• The first valid row is 1. (Taking the subset starting with 2 drops your first data value. The first array index is zero)
• Your file is not an excel file, just a delimited text file.

See if the attached can give you some ideas.

[jackhsu66]

Thank you so much for the constructive feedback, very appreciate your time!

My code indeed looked ugly... I really need to spend more time understanding the basics of dealing with arrays.

[Yamaeda]

A small addition to Altenbachs #1, Windows is very bad at keeping timing at sub 3ms periods. If you want to replay in a realistic manner it's probably better to plot 10 points at once in a 10ms loop.