Rockwell Automation Logix5000 Controllers Sequential Function Charts Programming Manual - Manual (Page 45)

Design a sequential function chart Chapter 1
In this example, a step turns on a fan and then calls another SFC. The nested SFC
sequences the remaining functions of the step. The fan stays on throughout the
steps of the nested SFC.
Example
Use a Large Step
This action turns on a fan.
• fan.ProgProgReq lets the SFC command the state of the fan.
• fan.ProgCommand turns on the fan.
This action calls another SFC. The SFC
sequences the remaining functions of
the step.
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 Do this
Automatically loop back to an earlier step Wire the last transition to the top of the step to which you want to go.
Stop and wait for a command to restart Use a stop element on page 45 .
Use a stop element
The stop element lets you stop the execution of an entire SFC or of a path of a
simultaneous branch and wait to restart.
When an SFC reaches a stop element, the following actions occur.
End the SFC
Rockwell Automation Publication 1756-PM006F-EN-P - October 2014 45