Introduction

The LD editor is used for graphical ladder diagram programming according to IEC 61131-3.

Representation

Representation of an LD section:

Objects

The objects of the LD programming language help to divide a section into a number of:

  • Contacts,

  • Coils,

  • Elementary Functions (EFs)

  • Elementary Function Blocks (EFBs),

  • Derived Function Blocks (DFBs)

  • Procedures

  • Control elements

  • Operation and compare blocks which represent an extension to IEC 61131-3

  • Subroutine calls

  • Jumps

  • Links

  • Actual Parameters

  • Text objects to comment on the logic

Properties

LD sections have a background grid that divides the section into lines and columns.

The LD programming language is cell oriented, i.e. only one object can be placed in each cell.

LD sections can be 11-63 columns and 17-3998 lines in size.

The program can be entered using the mouse or the keyboard.

Input Aids

The LD editor offers the following input aids:

  • Objects can be selected from the toolbar, the menu or directly using shortcut keys

  • Syntax and semantics are checked as the program is being written.

    • Incorrect objects are displayed in blue

    • Unknown words (e.g. undeclared variables) or unsuitable data types are marked with a red wavy line

    • Brief description of errors in the Quickinfo (Tooltip)

  • Information for variables and for elements of an LD section, that can be connected to a variable (pins, contacts, coils, operation and compare blocks), can be displayed in a Quickinfo (Tooltip)

    • type, name, address and comment of a variable/expression

    • type, name and comment of FFB pins, contacts etc.

  • Tabular display of FFBs

  • Actual parameters can be entered and displayed as symbols or topological addresses

  • Different zoom factors

  • Tracking of FFB links

  • Optimizing the link routes of FFB links

  • Display of inspection windows