1756-PM003H-EN-E, SFC and ST Programming Languages ...

Design a Sequential Function Chart 4-39
For additional information on how to nest an SFC, see “Nest an SFC”
on page 4-41.
End the SFC
Once an SFC completes its last step, it does not automatically restart at
the first step. You must tell the SFC what to do when it finishes the last
step.
To:
automatically loop back to an
earlier step
stop and wait for a command to
restart
Do this:
Wire the last transition to the top of the step to which you want to go.
See “Wire to a Previous Step“on page 4-14.
Use a Stop Element.
See “Use a Stop Element” on page 4-38.
Use a Stop Element
The stop element lets you stop the execution of an entire SFC or a
path of a simultaneous branch and wait to restart. When an SFC
reaches a stop element:
• The X bit of the stop element turns on. This signals that the SFC
is at the stop element.
• Stored actions remain active.
• Execution stops for part or all of the SFC:
If the stop element is at the end of a:
sequence
selection branch
path within a simultaneous branch
Then:
entire SFC stops
only that path stops while the rest of the
SFC continues to execute.
Publication 1756-PM003H-EN-E (excerpt from 1756-PM001H-EN-P) - August 2005