INITIALISATION AT THE START OF THE PROGRAM

When a program containing an SFC chart is launched (initialised), the program needs to know which operating phase must be activated first; i.e. which is the step containing a status token at the time of initialisation. To set up this step in the chart, at least one SFC function called INITIAL SFC STEP (INIT STEP) or RESETTABLE INITIAL SFC STEP (RESET-INIT) must be used per independent SFC chart.

An independent SFC chart describes a group of SFC functions interlinked by token type links between the I/O (status token circulation).

First example: An SFC chart has two INITIAL SFC STEP functions

Second example: Two independent SFC charts each have one INITIAL SFC STEP function

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