Sequential function charts

The Workflow module provides graphical views of flows, based on Sequential Function Chart (SFC) technology.

An SFC is a graphical programming language used for Programmable Logic Controllers (PLCs). It represents the sequential flow of steps in a process and supports the parallelization of actions with contingency for the completion of all parallel branches for forward flow to progress.

These are the main components of an SFC:

  • Steps with associated actions
  • Transitions with associated logic conditions
  • Directed links between steps and transitions

Steps in an SFC diagram can be active or inactive, with actions being executed for active steps only. A step can be active for one of these reasons:

  • It is an initial step as specified by the programmer
  • It was activated during a scan cycle and not deactivated since

Steps are activated when all steps above it are active and the associated condition of theconnecting transition is true. When a transition is passed, all steps above are deactivated at once and after all steps below are activated at once.

Workflow sequential flow chart

The Workflow module enables these SFC charts to be defined at these levels:

  • A Routing level to view all operations and their sequence
  • An Operation level to see all the phases and their sequence
  • A Phase level to see all actions and their sequence