Saving data to spread sheet file

[edmiles55]

I am having trouble saving all of my data to file. I am taking 4 current readings and want to observe any changes over a long time frame, 30 min or more. To do this I have 4 strip charts set up. The DAQ vi is set to read 200 data points at 5KHz. This allows from somewhat real time viewing on the strip charts. However when I save I am only able to save the last 200 data points for each channel. What I need to find is a way to either store all the points in a buffer at once, or given the length of time this experiment takes save the data directly to disk. The VI is simple it is a DAQ assistant which outputs to the data to a signal splitter then to the strip charts. The data directly out of the DAQ is all I need saved.

[Dennis_Knutson]

If you are only able to save the last scan, then my guess is that your file write is outside the loop or you haven't set the file write to append data. You haven't posted your code or said what file write function you are using. The defaults for both Write to Spreadsheet File and Write LabVIEW Measurement File are to create a new file and will not append.

[edmiles55]

I have tried the append to file but instead of four columns of data I recieve eight. the first four rows are 600 data points long while the last four are 200 the loop only runs twice. I attached the VI, if you have time to look at it I appricate the help.

[Dennis_Knutson]

You did two things incorrectly. First, you put your file write outside the loop. The only data passed out of a loop is the very last iteration unless you click on the exit tunnel and select Enable Indexing. Second, you wired a True constant to the transpose input of Write Spreadsheet to File - not the append. That's why your data is backwards. Why don't you try just the express VI Write to LabVIEW Measurement File inside the while loop. Merge your 4 different signals together an wire that to the signals input of it.

Message Edited by Dennis Knutson on 08-31-2006 10:08 AM