OPC UA MCP NPX Server

An NPX-based Model Context Protocol (MCP) server for OPC UA operations. This server provides a set of tools to interact with OPC UA servers, including reading/writing variables, browsing nodes, calling methods, and performing batch operations.

Features

- Read OPC UA Nodes: Read values from individual or multiple OPC UA nodes
- Write OPC UA Nodes: Write values to individual or multiple OPC UA nodes
- Browse Node Children: Explore the OPC UA address space by browsing node children
- Call OPC UA Methods: Execute methods on OPC UA objects with parameters
- Batch Operations: Perform multiple read/write operations in single requests
- Get All Variables: Discover all available variables in the OPC UA server address space
- Automatic Type Conversion: Intelligent conversion of values based on node data types
- Connection Management: Automatic connection handling with graceful disconnection

Installation & Usage

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You can run the server directly using NPX without installing it globally:

``bash
npx opcua-mcp-npx-server
`

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`bash
npm install -g opcua-mcp-npx-server
opcua-mcp-npx-server
`

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`bash
git clone
cd opcua-mcp-npx-server
npm install
npm run build
npm start
`

Configuration

The server connects to an OPC UA server using the following environment variable:

- OPCUA_SERVER_URL: The OPC UA server endpoint (default: opc.tcp://localhost:4840)

Example:
`bash
OPCUA_SERVER_URL=opc.tcp://192.168.1.100:4840 npx opcua-mcp-npx-server
`

MCP Tools

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Read the value of a specific OPC UA node.

Parameters:
- node_id (string): The OPC UA node ID in the format 'ns=;i='

Example:
`json
{
"node_id": "ns=2;i=1"
}
`


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Write a value to a specific OPC UA node.

Parameters:
- node_id (string): The OPC UA node ID
- value (string): The value to write (automatically converted to the correct type)

Example:
`json
{
"node_id": "ns=2;i=2",
"value": "75.5"
}
`

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Browse the children of a specific OPC UA node.

Parameters:
- node_id (string): The OPC UA node ID to browse

Example:
`json
{
"node_id": "ns=2;i=3"
}
`

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Read values from multiple OPC UA nodes in a single request.

Parameters:
- node_ids (array): List of OPC UA node IDs to read

Example:
`json
{
"node_ids": [
"ns=2;i=4",
"ns=2;i=5",
"ns=2;i=6"
]
}
`

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Write values to multiple OPC UA nodes in a single request.

Parameters:
- nodes_to_write (array): List of objects containing 'node_id' and 'value'

Example:
`json
{
"nodes_to_write": [
{"node_id": "ns=2;i=7", "value": "50"},
{"node_id": "ns=2;i=8", "value": "true"}
]
}
`

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Call a method on a specific OPC UA object node.

Parameters:
- object_node_id (string): The OPC UA node ID of the object containing the method
- method_node_id (string): The OPC UA node ID of the method to call
- arguments (array, optional): List of arguments to pass to the method

Example:
`json
{
"object_node_id": "ns=2;i=9",
"method_node_id": "ns=2;i=10",
"arguments": ["25.0", "high_quality"]
}
`

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Get all available variables from the OPC UA server, excluding those under the built-in 'Server' object.

Parameters:
- None required

Example:
`json
{}
`

Returns:
A comprehensive list of all variables with their properties including name, node ID, object ID, current value, data type, and description.

Integration with Cursor/Claude

This server can be integrated with Cursor IDE or Claude Desktop for OPC UA operations. Add the following to your MCP configuration:

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Add to your Cursor settings:

`json
{
"mcpServers": {
"opcua-npx": {
"command": "npx",
"args": ["opcua-mcp-npx-server"],
"env": {
"OPCUA_SERVER_URL": "opc.tcp://localhost:4840"
}
}
}
}
`

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Add to your Claude Desktop configuration file:

`json
{
"mcpServers": {
"opcua-npx": {
"command": "npx",
"args": ["opcua-mcp-npx-server"],
"env": {
"OPCUA_SERVER_URL": "opc.tcp://localhost:4840"
}
}
}
}
`

Example Usage in Conversation

Once configured, you can ask Claude to perform real-world OPC UA operations:

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- "What is the current temperature reading from the reactor vessel?"
- "Check the pressure level in Tank A"
- "Read all temperature sensors in the cooling system"
- "Get the current flow rate on production line B"

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- "Turn on the conveyor motor"
- "Set the mixer speed to 80 RPM"
- "Open valve V-101 to 75% position"
- "Start the circulation pump"
- "Set the heating element to 150°C"

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- "Start production on line 1 with rate 100 units/hour"
- "Stop all motors in emergency mode"
- "Initialize the batch reactor with recipe A"
- "Begin the cleaning cycle for Tank B"

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- "Show me all alarm states in the system"
- "Read all sensor values from the water treatment plant"
- "Check the status of all pumps and motors"
- "Get the energy consumption readings"
- "Discover all available variables in the OPC UA server"
- "Show me a complete inventory of all sensors and actuators"
- "List all process variables with their current values"

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`
User: "What's the temperature in reactor R-101?"
Assistant: I'll read the temperature sensor for reactor R-101.
Tool call: read_opcua_node with node_id "ns=2;i=11"
Result: "Reactor R-101 temperature: 87.3°C"

User: "Turn on the main conveyor motor"
Assistant: I'll start the main conveyor motor for you.
Tool call: write_opcua_node with node_id "ns=2;i=12" and value "true"
Result: "Main conveyor motor started successfully"

User: "Set the pump speed to 65%"
Assistant: I'll adjust the pump speed to 65%.
Tool call: write_opcua_node with node_id "ns=2;i=13" and value "65"
Result: "Pump speed set to 65%"

User: "Show me all available variables in the system"
Assistant: I'll get a complete list of all variables in the OPC UA server.
Tool call: get_all_variables
Result: "Found 15 variables:
- Name: Temperature_Sensor_01, NodeID: ns=2;i=101, Value: 87.3°C
- Name: Pressure_Sensor_01, NodeID: ns=2;i=102, Value: 2.5 bar
- Name: Flow_Rate_01, NodeID: ns=2;i=103, Value: 125.8 L/min
..."
`

Security Considerations

- This server currently connects without security (SecurityPolicy.None)
- For production use, implement appropriate security policies and authentication
- Ensure proper network security when connecting to industrial OPC UA servers
- Validate and sanitize all input parameters

Error Handling

The server provides detailed error messages for:
- Connection failures
- Invalid node IDs
- Type conversion errors
- Method call failures
- Read/write operation errors

Dependencies

- @modelcontextprotocol/sdk: MCP SDK for Node.js
- node-opcua: OPC UA client library for Node.js
- typescript: TypeScript compiler

Contributing

We welcome contributions to improve the OPC UA MCP NPX Server!

Repository: https://github.com/midhunxavier/OPCUA-MCP

To contribute:

1. Fork the repository at https://github.com/midhunxavier/OPCUA-MCP
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Make your changes
4. Add tests if applicable
5. Commit your changes (git commit -m 'Add some amazing feature')
6. Push to the branch (git push origin feature/amazing-feature`)
7. Open a Pull Request

Please feel free to open issues for bug reports, feature requests, or questions.

License

MIT License - see LICENSE file for details

Support

For issues and questions:
- Open an issue on GitHub
- Check the OPC UA server connectivity
- Verify node IDs are correct
- Ensure proper permissions for OPC UA operations
- Review server logs for detailed error information