Beckhoff TwinCAT Bridge

The Beckhoff bridge connects PLC Assist to your TwinCAT XAE project. Once running, PLC Assist can read your project tree, edit Structured Text code, compile, and more — the same workflow available for CODESYS.

Prerequisites

System Requirements

Make sure TwinCAT XAE is installed and you can open/edit PLC projects. No additional setup is needed — the bridge uses the Automation Interface which is included with TwinCAT.

Step 1: Download the Bridge

Click Connect in PLC Assist, then click Download Bridge to get BeckhoffBridge.exe.

Save it to a folder of your choice (e.g. C:\Tools\BeckhoffBridge).

Step 2: Open your TwinCAT project

Start Visual Studio (or TcXaeShell) and open your TwinCAT project. Make sure the project contains at least one PLC project.

Step 3: Start the bridge

Open a terminal and run:

BeckhoffBridge.exe

You should see output like:

BeckhoffBridge 1.0.0
Connecting to TwinCAT XAE...
Connected to project: MyProject
Starting HTTP server on port 8555...
TwinCAT Bridge listening on http://127.0.0.1:8555
Press Ctrl+C to stop.

Step 4: Connect from PLC Assist

In PLC Assist, select Beckhoff TwinCAT as the bridge type and click Connect. PLC Assist will automatically connect to localhost:8555.

Options

BeckhoffBridge.exe --port 8555    # Custom port (default: 8555)
BeckhoffBridge.exe --version      # Show version
BeckhoffBridge.exe --help         # Show help

Troubleshooting

"No running TwinCAT XAE instance found"

• Make sure Visual Studio or TcXaeShell is running
• Make sure a TwinCAT project (not just any VS solution) is open
• If multiple VS instances are running, close the ones without TwinCAT projects

"No TwinCAT project found in the open solution"

• The open solution must contain a TwinCAT XAE project
• If you just added TwinCAT to a solution, save and reopen it

"No PLC project found"

• Add a PLC project to your TwinCAT configuration (right-click PLC node > Add New Item)

COM Permission Errors

• Run the bridge with the same user account that started Visual Studio
• If using TcXaeShell, ensure it was started before the bridge

Port Already in Use

Use a different port:

BeckhoffBridge.exe --port 8558

For more help, see the troubleshooting guide.