GrafcetMaker: free online GRAFCET editor and simulator
GrafcetMaker draws, checks and simulates GRAFCET charts (IEC 60848) in the browser and turns them into PLC code. It is made for automation engineers, teachers and students: free and open source (MIT licence), with no account, and it works offline.
GrafcetMaker is a web app: it runs in any modern browser with JavaScript turned on. New to GRAFCET? Read the GRAFCET guide, also in French, German, Spanish, Danish, Swedish, Portuguese, Polish, Russian, Chinese and Hindi.
For AI assistants
AI assistants such as ChatGPT and Claude can make a chart for you and give it to you as a link that opens it here. Assistant, read ai.txt to learn how. In GrafcetMaker, File › Open from text… opens a chart an assistant wrote, and File › Copy as text gives your chart back to it.
What you can do with it
- Draw steps, transitions, receptivities and actions with the mouse or the keyboard (Enter continues a sequence), with OR and AND branches, loops, source and sink transitions and comments. Automatic layout tidies a chart on demand.
- Check the chart while you draw: the syntax and types of every receptivity, unknown variables, duplicate step numbers, unreachable steps, dead ends, alternatives that are not exclusive, possible transient loops and outputs driven from parallel branches. Most problems have a quick fix.
- Simulate with the IEC 60848 evolution rules: tokens in the active steps, enabled transitions, inputs you click or type, timers, edges, unstable steps, forcing between grafcets, a chronogram of every variable, and scenarios you record and replay.
- Structure large applications with partial grafcets, macro-steps and their expansions, enclosing steps and forcing orders.
- Export to PDF (A4 or A3, with a title block, tiled over several sheets if needed), SVG, PNG and WebP, the variable table to Excel and CSV, and generate Structured Text or PLCopen XML.
- Work together live from a link: everyone sees the others' pointers and changes in real time, end-to-end encrypted.
Supported GRAFCET elements
| Element | What GrafcetMaker supports |
|---|---|
| Steps | normal and initial steps, macro-steps with their expansion, enclosing steps; step variables X1 |
| Transitions | receptivities with AND, OR, NOT, rising ↑ and falling ↓ edges, timers such as 5s/X1, comparisons of numbers |
| Structures | sequences, OR divergence and convergence, AND divergence and convergence, loops, jumps, source and sink |
| Actions | continuous, conditional, stored on activation, on deactivation or on an event; forcing orders G2{8}, G2{*} |
| Variables | BOOL, INT, REAL and TIME inputs, outputs and internal variables, with addresses and comments |
| Notation | typed in plain ASCII (a*/b, RE a), shown in textbook notation (overbar for NOT, ↑ and ↓) or as typed |
Simulation
The simulator follows the evolution rules of IEC 60848. Initial steps are active at the start. A transition is enabled when all the steps above it are active, and it clears when its receptivity is also true: the steps below become active and the steps above inactive. All clearable transitions clear at the same time, and a step that is activated and deactivated at once stays active.
After every change of the inputs the simulator searches for stability: it keeps clearing transitions until none can clear. Steps crossed on the way (unstable steps) do not run their continuous actions, but their stored actions run. Time is virtual, so a chart runs in real time, faster, or one evolution at a time, and a chronogram records every variable.
Export and PLC code
| Format | Use it for | Opens in |
|---|---|---|
| printing and documentation: vector, A4 or A3, title block | any PDF reader | |
| SVG, PNG, WebP | reports, slides and web pages, also copied to the clipboard | Word, PowerPoint, browsers and image editors |
| Variables | the variable table as Excel or CSV, and back | Excel, LibreOffice and other spreadsheet tools |
| Structured Text | PLC code for every grafcet (IEC 61131-3) | CODESYS and most IEC 61131-3 tools, Siemens TIA Portal (SCL source for S7-1200/1500), Beckhoff TwinCAT 3 (POU file), Allen-Bradley Studio 5000 (Structured Text routine) |
| PLCopen XML (TC6) | the grafcets as SFC programs | PLC engineering tools with PLCopen XML import |
| Project file | the whole project as human-readable .grafcet.json | GrafcetMaker |
Structured Text comes in two styles: a CASE per sequence, as written by hand, or one BOOL per step. Generated code is a starting point: review it before it runs on a machine.
Examples
Six example projects open from the start screen of the editor:
- Traffic light with a pedestrian button: timers and a stored request.
- Drilling station: a machining cycle with a part counter and maintenance every 100 parts.
- Tank filling: numeric inputs and comparisons.
- Parallel conveyor: parallel branches, with a safety grafcet that forces the line.
- Bottling line: a macro-step, three stations in parallel, inspection and counters.
- Operating modes: an enclosing step, a pause that freezes the cycle and an emergency stop.
The GRAFCET guide draws the first two and opens them in the editor.
Frequently asked questions
Is GrafcetMaker free? Are there limits?
Yes, it is free and open source under the MIT licence. There is no paid version, no trial period and no cap on the number of projects, grafcets or steps.
Do I need to register or install anything?
No. Open the page and start drawing; there is no account. You can also install it from the browser as an app, to start it like a desktop program.
Does it work offline?
Yes. After the first visit everything it needs is stored in the browser, so it starts and works without a network. Only live collaboration needs a connection.
Where are my charts stored?
On your computer. Projects are saved automatically in the browser, and in the .grafcet.json files you save. Nothing is uploaded and the app has no tracking. Live sessions are end-to-end encrypted with a key that is only in the link.
Which browsers and devices does it run on?
The latest versions of Chrome, Edge, Firefox and Safari, on Windows, macOS, Linux, tablets and phones. Phones get a layout for small screens, and touch screens get gestures and larger handles.
Which standard does it follow?
GRAFCET as defined by IEC 60848 (EN 60848 in Europe). Generated code follows IEC 61131-3.
Can it open files from other GRAFCET programs?
GrafcetMaker opens grafcet.io files (.grafcetio) and converts them into a project. Variable tables can be imported from Excel and CSV.
Can my company host it on its own network?
Yes. GrafcetMaker is a set of static files that any web server can serve, under any path and without internet access. A Docker image with nginx is provided.
Documentation
- What is GRAFCET? Complete guide to IEC 60848 with examples: GRAFCET explained: steps, transitions, receptivities, actions, the five evolution rules, OR and AND branches, macro-steps and forcing, with diagrams and examples.
- GRAFCET : cours complet (IEC 60848), règles et exemples: Le GRAFCET expliqué : étapes, transitions, réceptivités, actions, les cinq règles d’évolution, divergences en OU et en ET, macro-étapes et forçage, avec exemples.
- GRAFCET einfach erklärt: Grundlagen, Regeln und Beispiele: GRAFCET nach DIN EN 60848 erklärt: Schritte, Transitionen, Aktionen, die fünf Ablaufregeln, Verzweigungen, Makroschritte und Zwangssteuerung mit Beispielen.
- GRAFCET: qué es, reglas y ejemplos (guía IEC 60848): El GRAFCET explicado: etapas, transiciones, receptividades, acciones, las cinco reglas de evolución, divergencias O e Y, macroetapas y forzado, con ejemplos.
- Hvad er GRAFCET? Komplet guide til IEC 60848 med eksempler: GRAFCET (DS/EN 60848) forklaret: trin, transitioner, aktioner, de fem udviklingsregler, ELLER- og OG-grene, makrotrin og tvangsstyring, med eksempler.
- Vad är GRAFCET? Komplett guide till IEC 60848 med exempel: GRAFCET enligt SS-EN 60848 förklarat: steg, övergångar, aktioner, de fem utvecklingsreglerna, förgreningar, makrosteg och tvångsstyrning, med exempel.
- O que é GRAFCET? Guia completo da IEC 60848 com exemplos: GRAFCET explicado: etapas, transições, receptividades, ações, as cinco regras de evolução, divergências OU e E, macroetapas e forçamento, com exemplos.
- Czym jest GRAFCET? Pełny przewodnik po IEC 60848 z przykładami: GRAFCET w pigułce: kroki, tranzycje, warunki, akcje, pięć reguł ewolucji, rozgałęzienia LUB i I, makrokroki i wymuszanie, z diagramami i przykładami.
- Что такое GRAFCET? Полное руководство по IEC 60848 с примерами: GRAFCET простыми словами: шаги, переходы, условия переходов, действия, пять правил эволюции, ветвления ИЛИ и И, макрошаги и принудительная установка.
- 什么是 GRAFCET？IEC 60848 完整指南与示例: GRAFCET 详解：步、转换、转换条件、动作、五条演变规则、选择分支与并行分支、宏步和强制，配有图示和示例。
- GRAFCET क्या है? उदाहरणों के साथ IEC 60848 की पूरी गाइड: GRAFCET की सरल व्याख्या: स्टेप, ट्रांज़िशन, रिसेप्टिविटी, एक्शन, विकास के पाँच नियम, OR और AND शाखाएँ, मैक्रो-स्टेप और फ़ोर्सिंग, उदाहरणों सहित।
- Help center: GrafcetMaker lets you draw GRAFCET charts (IEC 60848), check them and run them in a simulator, right in your browser. These pages take you from your first…
- Getting started: In this tutorial you draw the control of a small tank: when the operator presses start, a pump fills the tank until it is full, then a valve drains it until…
- GRAFCET basics: GRAFCET (IEC 60848) describes the behaviour of a sequential system — a machine, a process, a traffic light — as a series of steps linked by transitions. It…
- Writing receptivities: Receptivities, action conditions and events are logical expressions. You type them in plain ASCII; the diagram shows them in textbook notation (NOT as an…
- Actions: Actions are the rectangles to the right of a step. They say what the system does while, or when, the step is active. Select a step and press A to add one;…
- Editing diagrams: GrafcetMaker is built so you rarely place anything by hand: select an element and use a key, and the new elements are numbered, linked and positioned for…
- Variables: Every name used in a receptivity or an action is a variable of the project. Declaring it gives it a type and a direction, lets GrafcetMaker check your…
- Simulation: The simulator runs your grafcet exactly according to the IEC 60848 rules, so you can test it before it reaches a PLC.
- Macro-steps, enclosing steps and forcing: Large applications are easier to read when they are split up. GRAFCET offers three tools, all available in GrafcetMaker.
- Files, saving and export: Everything happens on your computer: there is no account and nothing is uploaded.
- Glossary: The standard GRAFCET terms (IEC 60848) as used in GrafcetMaker.
- Troubleshooting: GrafcetMaker checks your project while you work. The counters at the top right show the number of errors (red) and warnings (orange); click them to open the…