bacnet-wasm

BACnet/SC thin client for JavaScript/TypeScript via WebAssembly.

Provides a browser-compatible BACnet/SC (Secure Connect) client that connects to BACnet/SC hubs over WebSocket. Built on the rusty-bacnet protocol stack.

Installation

npm install @rusty-bacnet/bacnet-wasm

Quick Start

import { BACnetScClient, ObjectTypes, PropertyIds, encodeReal } from '@rusty-bacnet/bacnet-wasm';

// Create client and connect to SC hub
const client = new BACnetScClient();
await client.connect('wss://hub.example.com:1234');

// Read a property
const value = await client.readProperty(
  ObjectTypes.analog_input(), // object type
  1,                          // instance number
  PropertyIds.present_value() // property identifier
);
console.log('Present Value:', value);

// Write a property
await client.writeProperty(
  ObjectTypes.analog_value(),
  1,
  PropertyIds.present_value(),
  encodeReal(72.5),  // application-tagged value bytes
  8                   // priority (optional)
);

// Subscribe to COV notifications
client.onCovNotification((data) => {
  console.log('COV notification:', data);
});
await client.subscribeCov(1, ObjectTypes.analog_input(), 1, true, 300);

// Send Who-Is
client.onIAm((data) => {
  console.log('I-Am received:', data);
});
client.whoIs();

// Disconnect
await client.disconnect();

API Reference

BACnetScClient

| Method | Description | |--------|-------------| | new() | Create a new client (random VMAC) | | connect(url) | Connect to SC hub via WebSocket | | readProperty(objectType, instance, propertyId, arrayIndex?) | Read a property | | writeProperty(objectType, instance, propertyId, valueBytes, priority?) | Write a property | | whoIs(low?, high?) | Send Who-Is broadcast | | subscribeCov(processId, objectType, instance, confirmed, lifetime?) | Subscribe to COV | | onIAm(callback) | Register I-Am callback | | onCovNotification(callback) | Register COV notification callback | | disconnect() | Disconnect from hub | | connected | Property: connection status |

Value Encoding Helpers

| Function | Description | |----------|-------------| | encodeReal(value) | Encode a float as BACnet Real | | encodeUnsigned(value) | Encode an unsigned integer | | encodeBoolean(value) | Encode a boolean | | encodeEnumerated(value) | Encode an enumerated value |

Type Constants

• ObjectTypes — BACnet object type constants (e.g., analog_input(), device())
• PropertyIds — Property identifier constants (e.g., present_value(), object_name())

Architecture

This crate compiles the core BACnet protocol logic (types, encoding, services) to WebAssembly and bridges to the browser's native WebSocket API. BACnet/SC already uses WebSocket as its transport, making browsers a natural fit.

┌─────────────────────────┐
│  JavaScript/TypeScript   │
├─────────────────────────┤
│  BACnetScClient (WASM)  │
├──────────┬──────────────┤
│ SC Frame │  APDU/NPDU   │
│  Codec   │   Codec      │
├──────────┴──────────────┤
│  Browser WebSocket API  │
└─────────────────────────┘

License

MIT