SFC instances

I have an SFC chart with RunAlways execution mode and using this chart I write to tag different values. Every time when I save my project one more chart instance starts. I need to have only one running instance because other instances make manipulations with the same tag.
Is it possible to start only one instance of the chart? Or may be there is a way to control how many instances of the chart are running and close them?

Did you ever figure this out? I’m considering trying the SFC module, but may pass on it if it’s not mature.


This has been fixed in the latest iteration of the SFC module. Unfortunately its release got a bit delayed due to things going on with the platform, but it will be out with 7.7.7 and 7.8.2.

If you are currently using 7.7, you can go to downloads>early access>7.7 rc, and get just the sfc module.
On 7.8, you can go to early access>7.8 beta, and get just the module.


My understanding of the fix is that it will cancel your currently running version and start the new version whenever you save.

I didn’t want that, so when I complained about this same issue, and the above behavior was described to me, I implemented a global event script that will run every X seconds and check to see if the SFC is running, and if not it will start it up. This has the side effect of not having updates to charts be take affect unless you manually restart the chart, where updates to the global python script WILL be updated and take affect immediately. Also as a side benefit to figuring out about how to check if the chart is running I ended up writing a routine that all the charts run at start up making sure that it isn’t a duplicate instance, and if so, it exits.

Their way is safest of course, I don’t normally change the charts much, since most of my action steps actually just call shared script functions, and I didn’t want to have to worry about charts being restarted whenever I did a save.

Bill S.