Installing the CODESYS Bridge
Set up the PLC Assist bridge inside CODESYS in under a minute.
The CODESYS bridge is a single Python script that runs inside CODESYS. Once started, PLC Assist can read your project tree, edit code, compile, and report errors — all from your browser.
Requirements
| Requirement | Details |
|---|---|
| CODESYS | V3.5 SP18 or later |
| 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 CODESYS. You get a single file: plc-assist-bridge.py. It already contains your account token — no further configuration needed.
2. Run it in CODESYS
With your project open:
Tools → Scripting → Execute Script File → pick plc-assist-bridge.py.
That's it. The bridge takes about a minute to attach to CODESYS, finish loading the project, and connect to the cloud relay. While it's working, you'll see lines like Waiting for CODESYS to finish loading… — that's normal.
When it's ready you'll see:
IDENTITY Connected as <your-email>— confirms the bridge belongs to the account you're signed in to in the browser.[OK] Connected to relay — you can now use the chat.
The CODESYS window title also shows [Bridge Active].
3. 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
Closing CODESYS stops the bridge. 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When a newer bridge is released, the chat shows a "Bridge outdated" warning.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 file — your account token is preserved.
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 file 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"Bridge outdated" warning in the chat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 .py and run it again.
"Port 8555 already in use"
Another CODESYS instance on the same machine is running its own bridge. Close that one, or stop its bridge, and try again.
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.