Syntax

INITIAL_STEP name_1 :
  action_1();
  action_2();
  action_3(AQ);      (* with an optional action qualifier; 'AQ' is just a replacement for this. *)
  action_4(AQ,T#0s); (* with an optional action qualifier and a duration literal *)
  ...
  action_n();
END_STEP

Meaning

the initial →step within the →SFC network, name_1 must be an →IEC-identifier.
There must be exactly one initial step per SFC network. See the notes under "SFC elements in ST" how to create/use SFC networks efficiently and correctly.

One or several actions can be associated to the initial step: action_1(); ... action_n();The control of these actions is expressed by the optional action qualifier.

See "Evaluating the ST-code including the SFC networks" for information on when a step or initial step is active or inactive and the results of this.

The usage of the initial step is only possible within the current POU.

Example

INITIAL_STEP step0 :
  act0();
  actA0(N);
END_STEP

Using step flag and step times

It is possible to use the properties of the initial step. This is similar to using the properties of the step (see under "Steps in ST, Using step flag and step times").