# kukapay/modbus-mcp [Health: Active]

**Category:** 📟 Embedded System  
**Repository:** https://github.com/kukapay/modbus-mcp  
**GitHub Stars:** 25  
**Views:** 3  
**Installs:** 0  
**Upvotes:** 0  
**Directory Page:** https://allmcps.com/mcp/kukapay-modbus-mcp

## Description
An MCP server that standardizes and contextualizes industrial Modbus data.

## Claude Desktop Quick Installation
Heuristic fallback — verify the package name and runner against the repository README before running it. Uses `npx` (confidence: low):

```json
"mcpServers": {
  "modbus-mcp": {
    "command": "npx",
    "args": ["-y","kukapay-modbus-mcp"],
    "env": {
      "MODBUS_TYPE": "",
      "MODBUS_HOST": "",
      "MODBUS_PORT": "",
      "MODBUS_DEFAULT_SLAVE_ID": "",
      "MODBUS_SERIAL_PORT": "",
      "MODBUS_BAUDRATE": "",
      "MODBUS_PARITY": "",
      "MODBUS_STOPBITS": ""
    }
  }
}
```

**Requires environment variables:** `MODBUS_TYPE`, `MODBUS_HOST`, `MODBUS_PORT`, `MODBUS_DEFAULT_SLAVE_ID`, `MODBUS_SERIAL_PORT`, `MODBUS_BAUDRATE`, `MODBUS_PARITY`, `MODBUS_STOPBITS` — the values above are empty placeholders; fill in real credentials before running (see the repository for what each one is for).

## Documentation

## What kukapay/modbus-mcp MCP server does

The kukapay/modbus-mcp MCP server makes selected Modbus device operations available to MCP-compatible AI clients. It supports holding-register reads and writes, coil reads and writes, input-register reads, and multi-register holding-register reads. The server also provides an `analyze_register` prompt for interpreting register values with a customizable prompt.

This is suited to environments where an AI agent needs to inspect device state or issue supported Modbus commands through a client such as Claude Desktop. Write operations change device data, so deployments should be configured with the same access controls and operational safeguards used for other industrial control software.

## How it works

The server uses connection settings from the process environment or a `.env` file, then communicates with a configured Modbus device. The connection mode is selected with `MODBUS_TYPE`, which accepts `tcp`, `udp`, or `serial`.

Tool calls use structured parameters such as an address, count, value, and slave ID. For example, a holding-register read identifies the register address and slave ID, while a coil read also specifies how many coils to retrieve. Clients that translate natural-language requests into tool calls may allow conversational use, but the README notes that this depends on the client. The MCP Inspector requires structured JSON input.

## Setup and configuration

The project requires Python 3.10 or later and uses `uv` for dependency and virtual-environment management. The documented setup is:

1. Install `uv`.
2. Clone the repository.
3. Run `uv sync` from the repository directory.
4. Configure the server in the MCP client.

TCP and UDP connections use `MODBUS_HOST`, `MODBUS_PORT`, and the configured slave ID. Serial connections use `MODBUS_SERIAL_PORT`, `MODBUS_BAUDRATE`, `MODBUS_PARITY`, `MODBUS_STOPBITS`, `MODBUS_BYTESIZE`, and `MODBUS_TIMEOUT`. The documented defaults include localhost, port 502, slave ID 1, 9600 baud, no parity, one stop bit, eight data bits, and a one-second timeout. The configuration table names the slave-ID variable `MODBUS_DEFAULT_SLAVE_ID`, while the TCP example uses `MODBUS_SLAVE_ID`; verify the expected variable name in the project before deployment.

Claude Desktop can launch the server with `uv`, using the project directory and the `modbus-mcp` run target, while passing the Modbus environment variables in its server configuration.

## Tools and capabilities

Supported operations include:

- `read_register` for one holding register.
- `write_register` for one holding register.
- `read_coils` for a range of coils.
- `write_coil` for one coil.
- `read_input_registers` for a range of input registers.
- `read_multiple_holding_registers` for a range of holding registers.
- `analyze_register` for analyzing register values through a customizable prompt.

The available transport choices are Modbus TCP, UDP, and serial. The material does not document additional protocol functions, device discovery, scheduling, authentication, or data persistence.

## Limitations and notes

The README does not specify device-model compatibility, register schemas, retry behavior, concurrency guarantees, or safety validation for writes. Register addresses, counts, values, and slave IDs therefore need to match the target device’s Modbus documentation. Natural-language interaction is also client-dependent; structured tool input may be required.

The project is licensed under MIT. No paid API, external credential, or hosted service is described in the provided material.

_Full upstream README: https://allmcps.com/mcp/kukapay-modbus-mcp/readme_