Restart (Reset) The Sfc - Allen-Bradley Logix 5000 Programming Manual

Design a sequential function chart

Restart (reset) the SFC

If the SFC is
Nested (i.e., another SFC calls this SFC as a
subroutine)
Not nested (i.e., no SFC calls this SFC as a
subroutine)
If the stop element is at the end of a
• Sequence
• Selection branch
• Path within a simultaneous branch
Example
Use a stop element on page 48
Once at the stop element, you have several options to restart the SFC.
And the Last Scan of the Active Steps
option is
• Automatic reset
• Programmatic reset
• Don't scan
------------------------------->
Example
This example shows the use of the SFC Reset (SFR) instruction to restart the SFC
and clear the X bit of the stop element (see
Rockwell Automation Publication 1756-PM006I-EN-P - February 2018
Then
The entire SFC stops
Only that path stops while the rest of the SFC continues to
execute.
When the SFC reaches last_step and process_done is TRUE, the execution of the
SFC stops.
Then
At the end of the step that calls the nested SFC, the nested SFC automatically resets.
• The nested SFC resets to the initial step.
• The X bit of the stop element in the nested SFC clears to zero.
1. Use an SFC Reset (SFR) instruction to restart the SFC at the required step.
2. Use logic to clear the X bit of the stop element.
1. Use an SFC Reset (SFR) instruction to restart the SFC at the required step.
2. Use logic to clear the X bit of the stop element.
Restart (reset) the SFC
Chapter 1
on page 49).
49