Glossary
What is Step timeout?
A timer watching each step of a sequence: if the step does not finish in its expected time, raise a fault instead of waiting forever.
Without it the machine hangs silently: the valve never opened, the step waits for feedback that will not come, and the operator sees a frozen screen with no reason given.
The implementation is simple: a TON started on entry to the step, and if its Q arrives before the transition condition, the machine goes to a fault state with a message naming the step that failed.
Related terms
- State machine
- A pattern where the process is in exactly one known state at a time and moves between states on defined conditions.
- On-delay timer (TON)
- A standard function block whose output Q becomes true after IN has stayed true for PT without interruption, and resets as soon as IN drops.