Help us to help you. You can start by attaching a VI that shows some of your effort to accomplish your task. Among other things, it would tell us:
- What Version of LabVIEW you are using.
- What you mean by "an Excel file". Is this what LabVIEW calls a "Delimited Spreadsheet", a text file in "Comma-separated Values" (.csv), or a real Excel Workbook (.xlsx)?
- It would tell us if you are using NI's Report Generation Toolkit. This would let you:
- read an Excel .xlsx Workbook, look at a specified WorkSheet, and extract 2D data from specified Row/Column coordinates, which you can plot in the calling LabVIEW VI as a Graph.
- plot the above-mentioned 2D data as a Graph within an Excel Worksheet (of course, once you have 2D data from Excel, you can also plot it in LabVIEW as a Graph or a Chart, whichever is more appropriate).
A decade ago, I submitted a "Revised Generate Excel Report Example" (search for a title close to this name on the Search bar of this Forum). It should run, even though some of the RGT Function names have changed ("New Report" is now called "Create Report"). This example does not address reading Excel, but it does show you how to locate data and plot it on an Excel Worksheet.
For more help, attach your VI (best!) or provide answers to the points above, and provide more details on "what you know" and "what you want to do".
Bob Schor