EvenBetterFastSim is a desktop utility for emulating SEMI SECS/GEM equipment communication. It lets you emulate an equipment or host on your PC, and exchange HSMS/SECS-II messages manually or create your own scripted scenarios.
- HSMS (TCP/IP) communication with a live, timestamped message log
- An editable SECS/GEM message library loaded from XML (S1F1, S1F3, S2Fx, S6F11, …)
- Simulate workflows with multiple responses to a message using the Scenario canvas
- Create and define equipment events, reports and variables, and fire them as S6F11
- Run multiple instances at once (e.g. a Passive + Active pair) that talk to each other
- Control-state model (Online/Offline, Local/Remote) and configurable HSMS timers (T3–T8)
Use Visual Studio 2026 to open the .sln file.
You may download Visual Studio Community Edition for free to build, run or develop EvenBetterFastSim.
From the command line:
dotnet build EvenBetterFastSim.sln
dotnet run --project EvenBetterFastSim/EvenBetterFastSim.csprojYou can download the application using the following link Releases · Pre-Se/EvenBetterFastSim
Download the .zip file: it contains the exe together with the default
message library (Library\DefaultLibrary.msgpack).
Launching the app with no arguments opens the Hub. Each row is a named instance (a name plus an IP / port / connection mode/library); every profile launches as its own process so you can run several simulators side by side.
- New – add a single profile.
- New linked pair – create a Passive + Active profile that share one endpoint, so the two instances connect to each other the moment you launch them.
- Edit / Duplicate / Delete – manage existing profiles.
- Select a profile and click Launch instance (or double-click it).
Profiles live in %APPDATA%\EvenBetterFastSim\profiles\. Launching with --profile <name>
skips the Hub and opens that instance directly.
| Area | What it does |
|---|---|
| Left nav | Switches the centre panel between Messages, Events, Reports, Variables and Scenarios. |
| Centre panel | The library for the selected section, with a toolbar (Add / Modify / Duplicate / Delete / Send …). |
| Message Log (right) | Every SECS-II and HSMS control message, newest in order, with a ↑/↓ direction icon and millisecond timestamp. Double-click an item to inspect its tree (values shown as hex or Base64). |
| System Log (bottom) | Human-readable status: library loaded, connection changes, send failures, etc. |
| Status bar | The port toggle button, the HSMS state (Not Connected → Not Selected → Selected), comms-established flag, control state, and the Online / Offline / Local / Remote buttons. |
The window title shows the profile name and its endpoint so instances are easy to tell apart.
Open Connection ▸ Properties to set the IP address, port, connection mode (Passive = listen, Active = dial out) and the HSMS timers (T3–T8), session id, etc. When you launch from a Hub profile these are already filled in from the profile.
Click the port button in the bottom-left of the status bar to open/close the port. The connection restarts automatically if you change a setting while it is open.
In Messages, the tree is your SECS/GEM library (loaded from Library\SECSGEM_Library.xml
by default). Select a transaction and click Send — the primary message goes out and any
reply is paired up and shown in the Message Log. Use Add Transaction / Add Item / Modify
to shape the payloads, or Library ▸ Save Library to export your edits back to XML.
Define status/data variables under Variables, group them into Reports, then attach reports to a collection event under Events. Send Event builds and sends the corresponding S6F11 event report. (These lists start empty, populate them per your equipment model.)
The Scenarios section is a visual node graph for multi-step exchanges. Drag a transaction from the DRAG TO CANVAS palette onto the canvas, wire nodes from Start to End, and press Run to execute them in order against the live connection.
Node types: Send, Send & Wait (send and wait for the reply), Receive (wait for a matching incoming message, 30 s timeout) and Wait (a fixed delay). Scenarios are saved per instance and can be exported / imported.
Create a linked pair in the Hub and launch both. One listens (Passive), the other dials in (Active); once HSMS shows Selected on both, send a message from either side.