Manual

34 Publication LOGIX-UM001B-EN-P - April 2010
Chapter 3 Guidelines
Execution Guidelines
A state model makes it much easier to separate the normal execution of your
equipment from any exceptions (faults, failures, off-normal conditions).
HoldingIdle Running Held
Restarting
Stopping Aborting
Stopped Aborted
Resetting
Complete
Use the resetting, running, and stopping states
for the normal execution of the equipment.
Use the holding, restarting, and aborting states to
handle exceptions (faults, failures, off-normal
conditions).
Guideline Details
Use the prestate routine to watch for
faults
Use the prestate routine for conditions that you want to watch all the time such as fault bits.
The prestate routine:
• runs all the time.
• runs before each scan of a state.
• runs even in the waiting states (idle, held, complete, stopped, or aborted).
current state
routine
prestate routine