How to write to an existing file, but replace the data just to the last row

In my data acquisition system, the columns represent the channels and each represent line analysis of the data for all channels. It is easy to get the file write by add or replace a file exist. But sometimes I want to just overwriting new data in the last line in a file exist. for example: I have DAQ with 10 channels and scan all channels for three times in each race. So my data file will be 10 columns and 3 rows of each run if I put the file "append". next time I want to record the data by "crash" (so a single row of 3 scans) in the same file but just crash to 11th place (so I'm going to keep all the data I had previously). How to do this?

Hi GPIB Analyzer.

Why do you need to read the entire file?

You can:

-get the size of file with 'Get file size' or 'file info '.

-set the position of reading with "Set file position.

You should subtract the file size 1024, define what the position of the file read 1024 bytes. Now analyze this 1 KB of data, find the last line, set the file again, write to the file. No need to read the entire file.

And as previously stated:

How Labview should know the last line in the file without looking for him? You can do this research better than a simple brute force attack

Tags: NI Software

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