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Peroidic Datalogging?

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Hello all, I'm working on a program that can periodically log a few minutes of data once a week. So far, I've only been able to log data for a single event (one date, in this case). This seems like a fairly common problem, but I haven't been able to find any information on similar programs. Looking ahead, I also anticipate problems with the Write to Measurment block overwriting my previous data as well. My program is fairly similar to the sample NI tutorial program on data logging, so I'll leave a picture of that here. Thank you for your time.  

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Accepted by jcjones42

Hi jcjones,

 

I'm working on a program that can periodically log a few minutes of data once a week

Then you should not check for a certain period of time. You should check for those "few minutes once a week"…

 

I also anticipate problems with the Write to Measurment block overwriting my previous data as well.

You need to configure this ExpressVI more carefully. It supports an "append" mode when writing data…

Best regards,
GerdW


using LV2020 on Win8.1+cRIO
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So you're saying I shouldn't use a time stamp at all in my conditional statment? I think I follow, somewhat. The only issue I'd have then is controlling my intial start time.

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Accepted by jcjones42

Hi jcjones,

 

So you're saying I shouldn't use a time stamp at all in my conditional statment?

Yes: you can convert a timestamp to a cluster of time values ("date time record") and check hours, minutes, days seperately.

No: you could subtract the timestamp from "start of week" to get a relative time value. Then use InRange with relative values…

General answer: you should not use absolute timestamps (which include day and year) to compare for certain hour/minute values!

Best regards,
GerdW


using LV2020 on Win8.1+cRIO
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