Introduction

For every transition, a transition section can be created. This is a section containing the logic of the transition condition and it is automatically linked with the transition.

Name of Transition Section

The name of the transition section is always identical to the assigned transition, see Transition Name.

Programming Languages

FBD, LD, IL and ST are possible as programming languages for transition sections.

Suggested Networks for Transition Section:

Language

Suggested Network

Description

FBD

The suggested network contains an AND block with 2 inputs for which the output is linked with a variable having the name of the transition section.

The suggested block can either be linked or it can be deleted if desired.

LD

The suggested network contains a coil which is linked with a variable having the name of the transition section.

The suggested coil can either be linked or it can be deleted if desired.

IL

-

The suggested network is empty.

The content may only be created of Boolean logic. The assignment of the logic result on the output (the transition variable) is done automatically, i.e. the memory assignment ST is not allowed.

Example:

LD A

AND B

ST

-

The suggested network is empty.

The content may only be created of Boolean logic in the form of a (nested) expression. The assignment of the logic result on the output (the transition variable) is done automatically, i.e. the instruction assignment := is not allowed. The expression is not terminated by a semicolon (;).

Example:

A AND B

or

A AND (WORD_TO_BOOL (B))

Properties of Transition Sections

Transition sections have the following properties:

  • Transition sections only have one single output (transition variable), whose data type is BOOL. The name of these variables are identical to the names of the transition sections.

  • The transition variable can only be used once in written form.

  • The transition variable can be read in any position within the project.

  • Only functions can be used, function blocks or procedures cannot.

  • Only one coil may be used in LD.

  • There is only one network, i.e. all functions used are linked with each other either directly or indirectly.

  • Transition sections can only be used once.

  • Transition sections belong to the SFC section in which they were defined. If the respective SFC section is deleted then all transition sections of this SFC section are also deleted automatically.

  • Transition sections can be called exclusively from transitions.