Installing the Beckhoff Bridge
Set up the PLC Assist bridge for TwinCAT XAE in under a minute.
The Beckhoff bridge is a standalone Windows app that talks to your running TwinCAT XAE instance. Once started, PLC Assist can read your project tree, edit Structured Text, compile, and report errors — all from your browser.
Requirements
| Requirement | Details |
|---|---|
| TwinCAT XAE | 3.1 Build 4026 or later |
| IDE host | Visual Studio 2019 / 2022 (with TwinCAT XAE extension) or TcXaeShell |
| Operating System | Windows 10 / 11 (64-bit) |
You also need a PLC Assist account.
Setup
1. Download the bridge
In the PLC Assist chat, open the Set up bridge wizard and click Download for Beckhoff TwinCAT. You get a file named BeckhoffBridge-xxxx.exe — the -xxxx suffix is your one-time setup code. Leave the filename as-is — the bridge reads its own filename to pick up your account token.
Save it anywhere — your desktop, C:\Tools\, wherever convenient.
2. Open your TwinCAT project
Start Visual Studio (or TcXaeShell) and open your TwinCAT solution containing the PLC project. The bridge needs the IDE running to attach.
3. Run the bridge
Double-click BeckhoffBridge-xxxx.exe. A console window opens. You should see:
BeckhoffBridge 4.9.xIDENTITY Connected as <your-email>— confirms the bridge belongs to the account you're signed in to in the browser.Looking for TwinCAT XAE...→[OK] Attached to TwinCAT XAE[OK] Connected to relay — you can now use the chat.
If you start the bridge before opening the TwinCAT project, that's fine — it retries every 3 seconds and attaches as soon as TwinCAT comes up.
4. Switch back to the browser
The chat connects automatically via the cloud relay — no port, firewall, or localhost configuration. The bridge bar at the top of the chat turns green when the bridge attaches, and the tool is fully operational.
Stopping the bridge
Close the bridge console window (or press Ctrl+C in it). The chat's bridge bar returns to "Waiting for your bridge…" within a few seconds.
Updating
When a newer bridge is released, the chat shows a "Bridge outdated" warning. Re-download from the setup wizard and run the new .exe — your account token is preserved in the filename.
Troubleshooting
The chat says "Waiting for your bridge…" but the bridge is running
The bridge is probably signed in to a different account than the browser. Each account has its own cloud relay slot, so a bridge downloaded under one account never shows up on another.
Check the bridge console — near the top you'll see a line like:
[HH:MM:SS] STARTUP IDENTITY Connected as alice@example.comCompare that email to the one shown in the setup wizard. If they don't match, click Re-download for this account in the wizard and run the new .exe instead.
"Bridge outdated" warning in the chat
Re-download the bridge from the setup wizard. The version is pinned to what the server expects, so a fresh download always picks up the right version. Replace your old .exe and run it again.
"No running TwinCAT XAE instance found"
The bridge needs Visual Studio (or TcXaeShell) running with a TwinCAT solution open. Start the IDE first, open your solution, then run the bridge.
If both are running but the bridge still can't attach, make sure the bridge is launched as the same Windows user as Visual Studio — TwinCAT's COM interop won't cross user sessions.
Firewall
The bridge needs outbound WebSocket access to relay.plc-assist.com on port 443. No inbound ports are opened; you don't need to configure port forwarding. If your corporate firewall blocks outbound traffic to that host, allow it.