Design a sequential function chart
36 Rockwell Automation Publication 1756-PM006I-EN-P - February 2018
Each step of the SFC includes a millisecond timer that runs whenever the step is
active. Use the timer to for these situations.
• Signal when the step has run for the required time and the SFC should go to
the next step.
• Signal when the step has run too long and the SFC should go to an error
step.
The following shows the action of a timer and associated bits of a step.
Description
Step becomes active.
X bit turns on.
Timer (T) begins to increment.
Timer reaches the Preset (PRE) value of the step.
DN bit turns on.
Timer continues to increment.
Step becomes inactive.
X bit turns off.
Timer retains its value.
DN remains on.
Step becomes active.
X bit turns on.
Timer clears and then begins to increment.
DN bit turns off.
Transition after a specified
time
To Next Page
Loading...
Need help?
General
