[quote=“Carl.Gould”]Ok guys, so first of all it will always be true that without any PLC logic, a momentary button implemented in a software system will be open for the potential for latching on.
The reasons for this should be obvious: a “soft” momentary button isn’t a physical switch, it’s two separate write commands. It isn’t hard to concoct a situation where the second write command doesn’t happen: power down the entire scada system and boom - latched bit. Given this, the advice earlier in the thread about avoiding momentary buttons is good advice.
That said, I think it is certainly fair to say that under normal conditions, momentary buttons should just work. That is: we shouldn’t hide behind a general “momentaries are bad” advice to skirt around the real issue here, which is that there seems to be a race-condition affecting the momentary button.
We think we have this narrowed down (like all race conditions, it’s tricky to pin-point because it’s hard to verify 100% that you’ve fixed the issue if you can’t reliably reproduce it). We’ll re-work the section in question for 7.5.5 and I’ll post back here when progress is made on this ticket.[/quote]
the solution is simple. If the loss of focus on a momentary button is lost for what ever reason, the bool referenced by the button should be returned to its previous state.