Rockwell-automation Logix5000 Controllers Sequential Function Charts P Manuale Utente Scaricare il pdf (Pagina 77)

Chapter 3

Force steps

Use a force to override data that your logic either uses or produces.

• Test and debug your logic.

• 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.

Make sure you understand the following before using forces.

ATTENTION

Forcing can cause unexpected machine motion that could injure personnel. Before you use a force,

determine how the force will affect your machine or process and keep personnel away from the

machine area.

• 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.

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.

Introduction

Precautions

Enable forces

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Rockwell-automation Logix5000 Controllers Sequential Function Charts P Manuale Utente Pagina 77