ch340-can

An EventEmitter-based Node.js driver for USB-CAN adapters using the CH340/CH341 chip and Seeed binary frame protocol. Compatible with the Seeed Studio USB-CAN Analyzer and similar generic adapters commonly available under various brand names.

Not compatible with SLCAN text-protocol adapters (e.g. CANable) or SocketCAN-based devices.

Installation

npm install ch340-can

Usage

const CanBus = require('ch340-can');

const bus = new CanBus('/dev/ttyUSB0', { bitrate: 500 });

bus.on('open',  ()    => console.log('Listening...'));
bus.on('error', (err) => console.error('Error:', err.message));

bus.on('frame', (frame) => {
  console.log(`ID: 0x${frame.id.toString(16).toUpperCase()} DLC: ${frame.dlc} Data: ${frame.data.toString('hex')}`);
});

bus.open();

process.on('SIGINT', () => bus.close());

API

new CanBus(port, options?)

| Parameter | Type | Default | Description | |-----------|------|---------|-------------| | port | string | — | Serial port path, e.g. /dev/ttyUSB0 or COM3 | | options.bitrate | number | 500 | CAN bus bitrate in kbps | | options.silent | boolean | true | Listen-only mode — recommended for monitoring | | options.reconnect | boolean | true | Auto-reconnect on disconnect | | options.retryDelay | number | 1000 | Initial reconnect delay in ms | | options.retryMax | number | 10000 | Maximum reconnect delay after backoff in ms | | options.maxRetries | number | 0 | Max reconnect attempts before giving up (0 = forever) |

bus.open()

Opens the serial port and sends the initialization frame to the adapter.

bus.close()

Closes the serial port. Suppresses automatic reconnect.

Events

open

Emitted when the port is successfully opened.

close

Emitted when the port is closed intentionally via bus.close().

disconnect

Emitted when the port closes unexpectedly. Reconnect will be attempted automatically if reconnect is true.

reconnecting

Emitted before each reconnect attempt.

bus.on('reconnecting', ({ attempt, delay, max }) => {
  console.log(`Attempt ${attempt} in ${delay}ms`);
});

reconnected

Emitted when the port is successfully reopened after a disconnect.

error

Emitted on serial port errors or initialization failures.

frame

Emitted for each decoded CAN frame.

bus.on('frame', (frame) => {
  // frame.id    — number  — CAN message ID
  // frame.ext   — boolean — true = 29-bit extended, false = 11-bit standard
  // frame.rtr   — boolean — true = remote frame
  // frame.dlc   — number  — data length (0–8)
  // frame.data  — Buffer  — payload bytes
});

Supported Bitrates

500, 250, 125, 100, 50, 20, 10, 5 kbps and 1000, 800, 400, 200 kbps.

Requirements

• Node.js 14+
• serialport (peer dependency)

License

MIT