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Why didn't my recurring form trigger? (Continuous vs. Cumulative Time)

Explains why an OFS-Flow recurring form can fail to fire even when a machine state's total time exceeds the trigger threshold, because triggers track continuous spans, not accumulated time.

The issue

You have a form set to repeat every 120 minutes based on a machine state (e.g. Running). The form doesn't trigger, even though the machine has been Running for a total of 3 hours over the morning.

Why this happens

OFS-Flow triggers evaluate uninterrupted spans of a state. They don't buffer or accumulate time across separate events.

  • How it works: when the machine enters the target state (Running), a timer starts. If the machine stays in that state for the full duration set in your trigger (e.g. 2 hours), the form fires.
  • The gap problem: if the machine state changes — even for a single minute — the timer for that span is destroyed. When the machine returns to Running, the timer restarts from zero.

Example

  • 08:00 — Machine starts Running (timer starts).
  • 08:20 — Unplanned downtime for 5 minutes (timer is killed).
  • 08:25 — Machine starts Running again (timer starts at 0).
  • 10:05 — Machine is still Running.
  • Result: no form triggers. Even though the machine ran for 120+ minutes in total, the longest continuous span was only 1 hour 40 minutes.

Key caveats

  1. State sensitivity — any state not explicitly selected in your trigger breaks the chain. If your trigger only covers Running, then Run Slow will reset your timer.
  2. The Start toggle — with the Start toggle on, the form fires immediately when the state begins (or after the configured offset). The 2-hour repeat timer then begins after that first alert.
  3. Shift changes — depending on your configuration, a shift change or job change can also end a state span, resetting your frequency timer.

Best practice

If your production environment is prone to micro-stops or frequent short downtimes, a 2-hour machine-state repeat can be too fragile.

The alternative: use a shift-based trigger with a repeat interval instead. Shift triggers follow the wall-clock time of the shift rather than the machine's state, so the form fires every 2 hours regardless of technical interruptions. See this article for setting up count-based triggers.