So long story: the use case is operators currently manually record an online analyzer value at the time they take a sample. Then they run the sample through a measurement device in the lab, to compare the result with the online analyzer for QA purposes. Then they record these results on an HMI screen. Those values are stored in a holding register in a PLC, which then compares the difference and flags an alarm back to the HMI if the difference is out of spec. We use the PLC instead of simple built in HMI alarming because the allowed deviation is variable depending on the actual value or other factors.
So, now moving to Ignition - my first idea is just to replicate exactly, with individual OPC tags and a whole bunch of numerical data entry objects on a window that the operators click through like they do now on our existing HMI.
But I feel like there might be a better way that I'm just not aware of. Like some kind of data entry table where they can more easily tab through it...but I have no idea how to make a dataset where each piece of data is an OPC tag or if that is even possible.
We do need the tags historized so that if anything goes wrong we can prove we were performing the QA tests. And I don't think just using an SQL table for the data works because then I can't see how we would do the deviation alarming from there.
Are there any others out there that have done something similar and could share their ideas? We have a lot of resistance to our upgrade and any little win I can do to make HMI interactions quicker and easier for them will help immensely!
Manually entering multiple values for a specific sample...with history. Sounds like a job for Transaction Groups. Don't enable the tag history on the tag itself (it would be difficult to get back the exact values and exact timestamps when they occurred), create your user interface with the numerical entry components. On submit, perform calculations, save the results to some memory tags, and execute a transaction group to save the results into a database table. Of course you could also script some functions to run a named query to insert your data as well. I'm not clear on what the PLC is doing. Is there some additional parameters that only the PLC knows about the process that can't be done within Ignition? If you NEED the PLC, then create those OPC tags with your other memory tags to help in calculating the results.
Thanks! The PLC is checking what some specific conditions are (some are based on temperature that is a separate value, though that value does exist as an OPC tag in Ignition). Many are based on the value of the manual entry itself (for example if lab measured value is above 100, then acceptable deviation is 5, but under 100 than acceptable deviation is only 1, for example). Many are percentages of themselves (acceptable deviation is 2% of actual lab measured value). We moved all that to the PLC instead of trying to calculate it in iFIX...
So transaction groups...I've read of this term on the forum but have no knowledge...I guess I'm off to the University...