Hi guys,
I want to use Ignition as a tool to diagnose an intermittent (happens about once a day) anomaly in one of our machines.
My approach is to log a few Boolean OPC tags in a historical transaction group when the values change.
My question is should I be worried about using a 1 millisecond execution schedule? If so, how can I figure out the fastest execution schedule I can run without worry?
Regards,
D.Botha
Depends what protocol and device you’re trying to get this data from, but 1ms is probably too fast to get reliably.
Even if you can get a transaction group to run that fast, you are unlikely to get an OPC driver to run that fast. This is a job for the PLC to do.
Hi guys, thanks for the replies - job for the PLC makes sense but I would still like to know if there are any implications of running transaction groups too fast.
I mean I don’t think there is any implications but 1ms is just too fast and besides, what’s the point of 1ms schedule time if your tag scan class is not 1ms(or faster) because if it’s not then you’re wasting time scanning the tag every 1ms when the tag itself isn’t even being scanned that fast.
I suggest you set your tag scan class to 1sec and set your transaction group to 500ms and let it run for a day or so and see what kind of info you get.
If the issue that you are having happens that darn fast that you feel like you might miss it if you don’t scan it every 1ms then maybe you should latch those BOOL tags for a few seconds when they come on and then unlatch them (if the tags are coming from a PLC). This way you don’t have to scan them that fast.
Just my two cents 
Good luck! 