Rockwell Automation Publication 1756-PM004D-EN-P - September 2012 57
Chapter
3
Force I/O
Introduction
Use a force to override data that your logic either uses or produces. For example,
use forces to:
· test and debug your logic.
· check wiring to an output device.
· temporarily keep your process functioning when an input device has failed.
Use forces only as a temporary measure. They are not intended to be a permanent
part of your application.
Precautions
When you use forces, take these precautions.
Enable Forces
For a force to take effect, you enable forces. You can only enable and disable forces
at the controller level.
· You can enable I/O forces and SFC forces separately or at the same time.
· You cannot enable or disable forces for a specific module, tag collection, or
tag element.
ATTENTION: Forcing can cause unexpected machine motion that could injure personnel. Before you use a
force, determine how the force will effect your machine or process and keep personnel away from the
machine area.
– Enabling I/O forces causes input, output, produced, or consumed values to change.
– Enabling SFC forces causes your machine or process to go to a different state or phase.
– Removing forces may still leave forces in the enabled state.
– If forces are enabled and you install a force, the new force immediately takes effect.
If you download a project that has forces enabled, the application prompts
you to enable or disable forces after the download completes.
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