Append HMI Studio

Append HMI Studio designs operator screens (HMIs) for PLCs, runs them against live equipment, and publishes them as Windows installers for the target PC.

• Design screens on a diagram canvas, with tags, animation links, window properties and scripts.
• Run them in the editor against real devices through the bundled comms server:
  • EtherNet/IP ControlLogix/CompactLogix;
  • SLC 5/05 and MicroLogix;
  • Modbus TCP;
  • a built-in simulator.
• Alarms: analog and discrete alarms with acknowledgement, the _AlarmsActive, _AlarmsUnacked and _AckAll system tags, Alarm List and Alarm History objects, and daily CSV history. See doc/HMI_ALARMS.md.
• Retentive memory tags keep their last value from one run to the next.
• Users and security: users with access levels 0–9999, a built-in login window, the _Username and _AccessLevel system tags, login script functions, masked password entry and the Enable animation. See doc/HMI_SECURITY.md.
• Indirect tags: IndirectDiscrete, IndirectAnalog and IndirectMessage tags that a script points at any tag with LinkIndirectTag("Indirect", "Tag"), so one faceplate serves many devices. See doc/HMI_INDIRECT.md.
• Recipes: recipe books of tag values with optional paired PLC tags, script functions to save, load, upload, download, export, import, delete, rename and select recipes, and a Recipe List object. Recipes saved at run time are kept on the running PC. See doc/HMI_RECIPES.md.
• Automation: build, check, render and publish projects from the command line or a script, from a plain JSON spec. See doc/HMI_AUTOMATION.md.
• Publish a project as a Windows installer (HMI > Publish). It installs a locked, run-only copy of the app with the comms server, built on any platform. See doc/HMI_PUBLISH.md.

Projects are saved as .ahmi files. Files saved as .drawio-hmi by earlier builds still open.

Getting started

The User Manual (Word) walks through building an application with screenshots, using the LiquidWeighHMI example. In short:

1. Tags: in HMI > Devices, add your PLC (or use the simulator). Then define tags in HMI > Tag Dictionary.
2. Screens: draw them on the canvas. Each page is a window of the application.
3. Animation: select an object and add animation links on the Animation tab (colors, fill, movement, value display, touch actions).
4. Test: HMI > Run runs the project against live or simulated data.
5. Deploy: HMI > Publish builds a Windows installer for the target PC.

Documentation

Topic	Document
Building HMI applications, step by step	User Manual (PDF)
Alarms, system tags, alarm objects and history	doc/HMI_ALARMS.md
Users, access levels and login	doc/HMI_SECURITY.md
Recipe books, recipe functions and the Recipe List	doc/HMI_RECIPES.md
Indirect tags and LinkIndirectTag	doc/HMI_INDIRECT.md
Publishing a runtime installer	doc/HMI_PUBLISH.md
Command-line automation and the JSON project spec	doc/HMI_AUTOMATION.md
The PLC comms server and its protocol	comms/README.md
Building and packaging	doc/BUILDING.md
Releases	doc/RELEASE_PROCESS.md

For AI coding agents, .claude/skills/append-hmi-studio is a Claude Code skill for building and publishing HMI applications from the command line.

Download

Releases are published at github.com/AppendAutomation/AppendHMIStudio/releases:

• Append-HMI-Studio-<version>-Setup.exe
  • Windows 10/11 x64 installer, for all users (administrator rights).
  • Silent install: /S. Silent uninstall: "C:\Program Files\Append HMI Studio\Uninstall.exe" /S.
• Append-HMI-Studio-<version>-x86_64.AppImage: Linux, runs without installing.
• Append-HMI-Studio-<version>-amd64.deb: Debian and Ubuntu (sudo apt install ./Append-HMI-Studio-*.deb).

The installers are not code-signed yet, so Windows SmartScreen asks for confirmation on first run.

There is no automatic update: install a newer version over the old one.

Settings and logs are kept in %APPDATA%\Append HMI Studio (Windows) and ~/.config/Append HMI Studio (Linux).

Security

The app works offline. Diagram and project data never leave the machine, and the Content Security Policy forbids remotely loaded code. The only network traffic is to the PLCs a project is configured to talk to, through the local hmi-comms server.

A diagram can still reference external media (an image or font by URL). That media is fetched when the diagram is opened, so the remote server sees the request, but no diagram content is sent.

Building

See doc/BUILDING.md. In short, with Node.js 22.12+ and the .NET 8 SDK:

git clone --recursive https://github.com/AppendAutomation/AppendHMIStudio.git
cd AppendHMIStudio
npm install
npm start                 # run from source
npm run dist-win          # Windows installer (on Linux too, no wine)
npm run dist-linux        # AppImage and deb

The repository uses submodules; after a plain clone, run git submodule update --init --recursive.

Path	Contents
src/main/	Electron main process: windows, IPC, run-only mode, Publish, alarm/retentive/user stores
drawio/	Submodule: Append Automation's fork of the draw.io editor (branch hmi); the HMI code is in src/main/webapp/js/hmi/
comms/	hmi-comms, the .NET 8 PLC communications server, with the cslogix and cscomm3_slc submodules in comms/lib/
scripts/	Build scripts (dist-win, dist-linux, the Windows runtime template, icons, NSIS download)
build/	Icons, signing and fuse hooks
src/test/	Unit tests (npm test)
doc/	Documentation

License and attribution

Append HMI Studio is © 2026 Append Automation and is licensed under the Apache License 2.0 (see LICENSE).

It is built on the draw.io diagram editor and drawio-desktop by JGraph Ltd, used and modified under the Apache License 2.0. NOTICE lists the third-party works and the changes made. Append HMI Studio is not affiliated with or endorsed by JGraph Ltd; "draw.io" is a trademark of its owner.