I’m looking to validate my understanding of how tag groups work when you have different tag groups on tags looking at the same device (in my case, a modbus TCP device). I feel like I’m missing something pretty fundamental about how Ignition groups up these requests for execution behind the scenes, so it would be great if someone could give me a rundown of how it works (couldn’t find it in the docs, IU, etc)
What I want to do is to have tag groups with different history logging parameters, so I might have “My Device Slow History” and “My Device Fast History.” If I set both tag groups to have a direct execution rate of say 1 second, would Ignition be guaranteed to group them up into one batch of requests and fire it off every second - or could it end up staggered so some of the read requests might go off at 300ms past the second and some might go off at 700ms past the second?
The desireable outcome for me is for them all to be grouped up and execute together, so that the same number of requests are always hitting my device every time period. I also am heavily reliant on the only one concurrent request option, so it’s important to retain that functionality.
Once I’ve got my head around that one, I’d also like to understand what happens if I set half of the tags for my modbus device to 1 second and half to 3 seconds. Would it do a full poll every 3 seconds, then just do whatever polling it needs to on the other 2 cycles to collect just that group of tags? i.e. if I have span gaps on it would grab some smaller subset of tags, but if I don’t have span gaps on it would send many requests since some of my tags are only on the 3 second cycle?
Hopefully that made sense! Sorry for the wall of text.