SFC Steps

A step represents a stable state.

  • It is drawn as a square box in the SFC chart.
  • Each step of a program is identified with a unique number.
  • At runtime, a step can be either active or inactive according to the state of the program.

  • Select a step, transition, or jump and press Ctrl+ENTER to change its number.

All actions linked to the steps are executed according to the activity of the step.

Inactive Step

Active Step

In conditions and actions of the SFC program, you can test the step activity by specifying its name (i.e., GS then the step number followed by .X).

Example

GS100.X
  • Is TRUE if step 100 is active.
  • Expression has the BOOL data type.

You can test the activity time of a step, by specifying the step name followed by .T.

  • It is the time elapsed since the activation of the step.
  • When the step is deactivated, this time remains unchanged.
    • It is reset to 0 (zero) on the next step activation.

Example

GS100.T

Is the time elapsed since step 100 was activated.

Expression has the TIME data type.

Initial Steps

Initial steps represent the initial situation of the chart when the program is started.

  • There must be at least one initial step in each SFC chart.
  • An initial step is marked with a double line: