IEC programming languages

Powerful programming editors for efficient engineering

Description

SIMATIC STEP 7 (TIA Portal) provides powerful programming editors for programming SIMATIC S7 controllers

  • Structured text (SCL), ladder logic (LAD) and function block diagram (FBD) languages are available for all controllers.

  • Statement list (STL) and step sequence programming* (GRAPH, SFC) are additionally available for the controller series S7-300, S7-400, WinAC and new S7-1500.

Functions such as drag & drop, project-wide cross-reference list and Intellisense provide users with intuitive tools for all tasks. STEP 7 (TIA Portal) therefore enables efficient creation of user programs. It is also straightforward to have different programming languages in a single block.

Programming editors and the latest Windows technologies adapted to tasks and processing provide the basis for the intuitive STEP 7 (TIA Portal) operating concept. The embedding of the various editors in a common working environment ensures that all data is available to the user on a consistent basis and an overview of the project data is assured at all times.

Program blocks can be saved at any time. Troubleshooting is made easier and quicker thanks to several tools – a syntax window lists all errors in the current block. This permits simple navigation between the errors and has an indicator for faulty networks.

* Support of GRAPH for S7-1500 controllers – to follow

LAD and FBD – graphic programming languages

With STEP 7 (TIA Portal) , graphic programming languages are supported by new, high-performance compilers. Powerful tools and integrated functionality, such as indirect programming, boost engineering efficiency when creating programs.

The user-friendly, fully graphical LAD and FBD editors offer excellent clarity and fast navigation in the block editor thanks to

  • opening and closing entire networks

  • showing and hiding symbols and addresses

  • direct zooming and saving of layouts

  • a host of keyboard shortcuts

  • lasso function, copying and pasting for individual commands and command structures

  • comments

  • New CalculateBox permits the direct input of formulas for the S7-1200 and
    S7-1500


SCL (Structured Control Language) – Programming of complex algorithms

The Structured Control Language (SCL) corresponds to the textual high-level language ST (Structured Text) defined in the standard IEC 61131-3 and fulfills base level and reusability level requirements according to PLC open. SCL is particularly suitable for the high-speed programming of complex algorithms and arithmetic functions and for tasks in data processing. The SCL code is simpler, shorter and clearer to produce and handle. Programming efficiency is enhanced using new, high-performance SCL compilers.

S7-SCL Editor offers the following functionalities:

  • Complete areas of program code can be activated/deactivated with just one click

  • Loops and multi-line comments can be expanded and collapsed

  • Bookmarks

  • Export of SCL code

  • Fast access to tag parts (bit, byte, word...) with "slicing"

  • The values of all tags are displayed clearly online

  • SCL blocks can be used in other STEP 7 languages

  • Ideal for user-defined function blocks for libraries

  • SCL blocks form the basis for sharing program code between S7-1200, S7-300, S7-400 and WinAC

  • Considerable time savings compared to programming in LAD/FBD/STL


STL – Statement list

The statement list (STL) textual programming language enables the creation of hardware-level runtime and memory-optimized user programs.

It supports the user with a host of new user-friendly editing functions:

  • Intelligent selection of symbols from PLC tags, DBs, local tags

  • Clear presentation even of complex program code

  • Code can be activated/deactivated with  just one click

  • Option of adding display of absolute addresses

  • Breakpoints can be set directly

  • Clear online presentation


GRAPH (SFC) - Programming of sequencers

Sequential Function Chart (SFC) is used for describing procedures with alternative or parallel sequencers.

The sequencers are configured and programmed clearly and quickly in a standardized display mode (in line with IEC 61131-3, DIN EN 61131).

The process is described graphically and divided into individual steps with a manageable scope of functions.

Basic functions

  • Flexible sequencer structure:
    Simultaneous and alternative branches, jumps within the sequencers, step activation and deactivation.

  • Selective processing of steps.
    The processing time of a sequencer is thus independent of the number of steps.

  • Synchronisation of automatic and manual mode:
    The process is no longer synchronous if it was put into a different state manually. GRAPH supports the locating of synchronization points for restarting automatic operation. The relevant steps are marked for this purpose. Transitions or interlocks can be defined as criteria

  • Single-step presentation shows all details of a step at a glance

  • Considerable time savings compared to programming in LAD/FBD/STL

Test and diagnostics functions
Online functions: The online functions can result in considerable time savings, particularly during the commissioning phase. For example, active steps, the status of the interlocking, monitoring and step enabling conditions, and past actions can all be displayed online.