sylo-codesys

Drive a live, open CODESYS V3.5 project from Sylo chat — create POUs, write Structured Text, compile, read/write PLC variables — with changes appearing in the CODESYS IDE in real time.

This package does not speak MCP and does not spawn CODESYS. It is the skill + a setup/diagnostic tool. The actual CODESYS tools come from the external codesys-mcp-sp21-plus stdio MCP server, surfaced into Pi by the pi-mcp-adapter package once you add a codesys server to a workspace .mcp.json.

Requirements

• CODESYS V3.5 SP19 / SP21 / SP22 installed (Windows).
• Node.js 18+ (for the MCP server).
• The pi-mcp-adapter package enabled in Sylo → Capability manager.
• The global npm package codesys-mcp-sp21-plus:

  npm install -g codesys-mcp-sp21-plus
  

Setup

1. Enable sylo-codesys in Sylo → Capability manager → Sylo optional packages.

2. Enable pi-mcp-adapter (separate package) if it isn't already.

3. In Sylo chat, ask the agent to call codesys_setup_check. It detects your CODESYS install, verifies the npm package, checks for a codesys server in your .mcp.json, confirms the mcp adapter is live, and prints a ready-to-paste, augmented .mcp.json snippet.

4. Paste that snippet into your workspace .mcp.json (merge into the existing mcpServers object). The recommended entry looks like:

   {
     "mcpServers": {
       "codesys": {
         "command": "codesys-mcp-sp21-plus",
         "args": [
           "--codesys-path", "C:\\Program Files\\CODESYS 3.5.22.30\\CODESYS\\Common\\CODESYS.exe",
           "--codesys-profile", "CODESYS V3.5 SP22 Patch 3",
           "--mode", "persistent",
           "--no-auto-launch",
           "--auto-mirror"
         ],
         "lifecycle": "lazy-keep-alive",
         "requestTimeoutMs": 180000,
         "directTools": ["get_codesys_status", "get_project_info", "get_all_pou_code", "create_pou", "set_pou_code", "create_method", "create_property", "create_dut", "create_gvl", "create_folder", "delete_object", "rename_object", "save_project", "compile_project", "get_compile_messages", "add_library", "list_project_libraries", "connect_to_device", "read_variable", "write_variable", "start_stop_application", "get_application_state", "mirror_export", "shutdown_codesys"],
         "approveTools": ["delete_object", "write_variable", "force_variables", "unforce_variables", "download_to_device", "reset_application", "shutdown_codesys", "remove_library"]
       }
     }
   }
   

   Get the exact --codesys-path / --codesys-profile strings with codesys-mcp-sp21-plus --print-config (the setup tool does this for you).

5. Restart the broker so pi-mcp-adapter re-reads .mcp.json.

6. In chat, ask the agent to drive CODESYS (e.g. "create a POU FB_Motor in Application and compile"). The first tool call launches CODESYS (persistent, UI visible); with lazy-keep-alive it stays resident across turns.

How it works

Sylo agent (LLM)
   │  calls codesys_create_pou, codesys_compile_project, …  (directTools)
   │  or mcp({ tool: "create_pou", args })                   (proxy, other tools)
   ▼
pi-mcp-adapter  (Pi extension; spawns + owns the MCP server stdio process)
   ▼
codesys-mcp-sp21-plus   (Node, stdio MCP server)
   │  file-based IPC: writes command .py → watcher polls → result
   ▼
CODESYS.exe             (persistent, --runscript=watcher.py, UI visible)
   ▼
open .project           (live; operator watches changes in the IDE)

Notes

• Modifying tools (set_pou_code, create_pou, …) auto-save the project. Ctrl+Z in the IDE does not recover set_pou_code edits. With --auto-mirror, each change re-runs mirror_export to a .st mirror on disk — commit that mirror to git for real undo.
• connect_to_device may pop a "Device User Login" modal in the IDE. Pre-set CODESYS_DEVICE_USER / CODESYS_DEVICE_PASSWORD in the server env block to suppress it.
• MCP-server compatibility & docs: see the codesys-mcp-sp21-plus README and ARCHITECTURE.md.