Introduction

A transition provides the condition through which the checks of one or more pre-transition steps pass on one or more consecutive steps along the corresponding link.

Transition Condition

Every transition is allocated with a transition condition of data type BOOL.

The following are authorized as transaction conditions:

  • an address (input or output)

  • a variable (input or output)

  • a Literal or

  • a Transition Section

The type of transition condition determines the position of the name.

Transition Condition

Position of the Name

  • Address

  • Variable

  • Literal

  • Transition Section

Transition Name

If an address or a variable is used as a transition condition then the transition name is defined with that name (e.g. %I10.4, Variable1).

If a transition section is used as a transition condition then the section name is used as the transition name.

Transition names (maximum 32 characters) must be unique over the entire project, i.e. no other transition, variable or section (with the exception of the assigned transition section) etc., may exist with the same name. There are no case distinctions. The transition name must correspond with the standardized name conventions.

Enabling a Transition

A transition is enabled if the steps immediately preceding it are active. Transitions whose immediately preceding steps are not active are not normally analyzed.

NOTE: If no transition condition is defined, the transition will never be active.

Triggering a Transition

A transition is triggered when the transition is enabled and the associated transition conditions are satisfied.

Triggering a transition leads to the disabling (resetting) of all immediately preceding steps that are linked to the transition, followed by the activation of all immediately following steps.

Trigger Time for a Transition

The transition trigger time (switching time) can theoretically be as short as possible, but can never be zero. The transition trigger time lasts at least the duration of a program cycle.