I use Datalink and PICompDat to pull lab results, call it Tag1, into Excel. I'm never sure what the frequency or time stamp will be, or even whether the test was being run, so Compressed data works best to pull in all the available results. For each Tag1 value, I then want to get a result for Tag2, a different lab test, from around the same time. By tieing them together on the same row, I can then do some calcs with the two values, run statistics, etc.
Typically, I've used PiTimedDat for Tag2, referencing the timestamps of Tag1. But if Tag2 values do not exist for whatever reason, PI will interpolate a result from days, even weeks old data! I tried using exact time for the retrieval mode, but the time stamps never exactly match up and I get no Tag2 data.
If no Tag2 data exists within an couple hours, I rather have a blank, or a flag I can test for in Excel, because I could then calculate a value from other data.
We're relatively new to PI, so presumably there is a way around this. Thanks in advance.