---
title: Properties
icon: settings-2
---

The BACnet MCP server leverages FastMCP 2.0's core building blocks - resource templates, tools, and prompts - to streamline BACnet read and write operations with minimal boilerplate and a clean, Pythonic interface.

### Read Properties

Each object on a device is mapped to a resource (and exposed as a tool) and [resource templates](https://gofastmcp.com/servers/resources#resource-templates) are used to specify connection details (host, port) and read parameters (instance, property).

```python
@mcp.resource("udp://{host}:{port}/{obj}/{instance}/{prop}")
@mcp.tool(
    annotations={
        "title": "Read Property",
        "readOnlyHint": True,
        "openWorldHint": True,
    }
)
async def read_property(
    host: str = settings.bacnet.host,
    port: int = settings.bacnet.port,
    obj: str = "analogValue",
    instance: str = "1",
    prop: str = "presentValue",
) -> str:
    """Reads the content of a BACnet object property on a remote unit."""
    ...
```

### Write Properties

Write operations are exposed as a [tool](https://gofastmcp.com/servers/tools), accepting the same connection details (host, port) and allowing to set the content of an object property in a single, atomic call.

```python
@mcp.tool(
    annotations={
        "title": "Write Property",
        "readOnlyHint": False,
        "openWorldHint": True,
    }
)
async def write_property(
    host: str = settings.bacnet.host,
    port: int = settings.bacnet.port,
    obj: str = "analogValue,1",
    prop: str = "presentValue",
    data: str = "1.0",
) -> str:
    """Writes a BACnet object property on a remote device."""
    ...
```
