How to capture a device LCD to number

I want to find a solution to convert any handheld instrument digital readout into a data stream that it can plot as a chart based on a preset time interval like this:

LCD to number chart

Using a webcam to capture and dump the data to a spreadsheet to plot the chart. I did look into source code like ssocr, capture2txt etc, but none of them can do a complete solution. Any suggestions welcome. Thanks.


 
 
 
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