I have a question regarding the behaviour of the Pulse (P/P1) action qualifier in SFC programming.
There seems to be a strange behaviour when using a Pulse action for the same variable in two (or more) consecutive steps.
The pulse is missing for all following steps after the first apperance. (see red marking on screenshot)
If there is at least one step between those actions, the behaviour is as expected and the pulse is always triggered correctly. (second screenshot)
this behavior is intentional and not a bug. Pulse qualifiers (P and P1) generate a pulse only when a step becomes active. If the same Boolean variable is used with a Pulse qualifier in two immediately consecutive steps, the internal IEC action control flag prevents the same action from firing again right away. This flag exists to ensure an IEC action is not executed multiple times in succession when triggered again too quickly by another step.
When at least one neutral step lies in between, the internal flag has time to reset — which is why the pulse appears correctly again in the next step.
Workaround:
Use separate BOOL variables for each pulse action (e.g., Pulse_S1, Pulse_S2, …) and later combine them with OR.This avoids the internal control‑flag suppression because each step drives its own independent pulse signal.
