Rockwell Automation Logix5000 Controllers Sequential Function Charts Programming Manual - Manual (Page 44)

Chapter 1 Design a sequential function chart
When the SFC leaves the step that stores the action, the Logix Designer
application continues to show the stored action as active. By default, a green
border displays around the action. This lets you know that the SFC is executing
the logic of that action.
To use a stored action, follow these guidelines.
• The Reset action only turns off the stored action. It does not automatically
turn off the devices of the action. To turn off the device, follow the Reset
action with another action that turns off the device. Or use the Automatic
reset option described in Use the automatic reset option on page 40 .
• Before the SFC reaches a stop element, reset any stored actions that you do
not want to execute at the stop. An active stored action remains active even
if the SFC reaches a stop.
• Use caution when you jump in between a step that stores an action and a
step that resets the action. Once you reset an action, it only starts when you
execute the step that stores the action.
In this example, step_1 – step_4 require a fan to be on. At the end of
step_4, the fan is reset (turned off). When the SFC jumps back to step_3,
the fan remains off.
To turn the fan back on, the SFC has to jump back to step_1.
Use one large step
If you use one large step for multiple functions, then use additional logic to
sequence the functions. One option is to nest an SFC within the large step.
44 Rockwell Automation Publication 1756-PM006F-EN-P - October 2014