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IEC 61131 Compliance

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ISaGRAF IEC 61131 Compliance

The ISaGRAF Application development Workbench supports all of the standard IEC 6-1131 control program languages as well as Flow Chart.

These Languages are:

SFC: Sequential Function Chart

FBD: Function Block Diagram

LD: Ladder Diagram

ST: Structured text

IL: Instruction List

FC: Flow Chart

You may use any or all of the control languages in your application as it best suits your needs.

Sequential Function Chart (SFC)
Sequential Function Chart (SFC), the core language of the IEC 61131-3 standard, divides the process cycle into a number of well-defined steps, separated by transitions. The other languages are used to describe the actions performed within the steps and the logical conditions for the transitions. Parallel processes can easily be described using SFC.

ISaGRAF's SFC Editor provides efficient and easy-to-use editing features, both mouse and keyboard driven. It has a Graphic User Interface (GUI) to color-coded chart elements in an easy-to-use grid for element insertion, selection and movement. During the development, the chart is automatically rearranged to provide a clean display. The Level 2 SFC, which is the program performed in a step, is displayed on-screen in a resizable window. Many powerful, timesaving features have been incorporated into the SFC editor; for example, the SFC Gallery enables fast insertion of complex SFC structures from managed templates.

Function Block Diagram (FBD)
Function Block Diagram (FBD) is a graphical language that allows the user to build complex procedures by taking existing function blocks from the ISaGRAF library, and wiring them together on screen. As you would expect from ISaGRAF, the diagrams are color-coded and can be zoomed into view the whole diagram or specific areas in more detail. Modifications to the diagram are tracked and highlighted, to the extent that sections can be marked for deletion, while still visible in the code.

Ladder Diagram (LD)
The Ladder Diagram (LD) is one of the most familiar methods of representing logical equations and simple actions. Contacts represent input arguments and coils represent output results. ISaGRAF's Quick LD editor provides the best compromise between high-level graphic capabilities and easy-to-use keyboard driven programming. Each block in the selection list has a description text with the option for manual text input from the keyboard. With ISaGRAF, users can mix LD and FBD programming in the same chart.

Structured Text (ST)
Structured Text (ST) is a high level structured language with a syntax similar to Pascal but more intuitive to the automation engineer. This language is primarily used to implement complex procedures that cannot be easily expressed with graphical languages (e.g. IF / THEN / ELSE, FOR, WHILE...). ISaGRAF's ST editor guides the user to the correct syntax and punctuation. To further facilitate and speed development, ISaGRAF provides highly useful validation and programmer assistance facilities.

Instruction List (IL)
The Application Workbench also includes Instruction List (IL), a low-level Boolean language similar to the simple textual PLC languages that are programmed at the register level.




Flow Chart
Recognizing that virtually every engineer graduating from college today has programmed in Flow Chart, the Workbench fully supports graphical Flow Chart programming. The Flow Chart is an easy to read decision diagram where actions are organized in a graphic flow. Binary decisions are used to control the flow. The Flow Chart Editor has full support for connectors and sub-programs. Actions and tests can be programmed in LD, ST or IL. The graphical editor allows each symbol to be resized independently, and automatically arranges the chart during development.

Additional Options

"C" User Program Support
Additionally, for ultimate power and flexibility, the Workbench supports "C" user programs written in one of the following ways:

  • Functions and function blocks written in C that can be called directly from any of the six supported languages. These routines become an extension of the ISaGRAF languages. C functions and function blocks can be used to access any resources of the target system (e.g. writing files, mailbox, etc.).
  • On multitasking systems, user tasks written in C can run in parallel with the ISaGRAF program. Such tasks can be used to display graphics, interface to networks or disks, or perform complex algorithms such as motion control. C function blocks can also send or receive any data from user tasks running in parallel with ISaGRAF.