States, Modes and Events

Introduction

A State is an abstraction of the system’s hardware state. For instance the system can be In OFF State, where power to the drives and motors is off, or ENGAGED State where the system is tracking external setpoints or executing a motion program.

A Mode is an abstraction of the way how signals are routed through the control system. The system can for instance be in Automatic Mode or Manual Mode.

There are also intermediate States/Modes between other State/Modes. These are be called Transitions or Transitional States/Modes. Transitions are protected by a Timeout if the system remains in the Transition for too long (for instance the system is commanded to go from OFF to IDLE State and because of some hardware failure it cannot switch on the drives, a timeout error will occur in the Transitional State OFF_TO_IDLE).

An Event is a trigger that initiates some change in the Control System, such as changing States or Modes. Events can be triggered by user interaction or programmatically.

States

Modes