Overview
The serial node provides UART (Universal Asynchronous Receiver/Transmitter) communication
for connecting GPS modules, Arduino boards, Modbus devices, industrial sensors, and other serial equipment.
Voltage Level Warning
Raspberry Pi uses 3.3V logic. Never connect 5V serial devices directly! Use a logic level converter for Arduino (5V) or RS-232 devices. Direct 5V connection can damage your Pi.
Raspberry Pi Serial Ports
Primary UART (ttyAMA0)
Enable UART
# Edit /boot/config.txt
enable_uart=1
# Disable Bluetooth (use full UART)
dtoverlay=disable-bt
# Or use mini UART for Bluetooth
dtoverlay=miniuart-btProperties
| Property | Type | Required | Default | Description |
|---|---|---|---|---|
| port | string | Yes | - | Serial port path (e.g., /dev/ttyAMA0) |
| baudRate | number | No | 9600 | Communication speed |
| dataBits | number | No | 8 | Data bits (5, 6, 7, or 8) |
| parity | string | No | "none" | "none", "even", "odd", "mark", "space" |
| stopBits | number | No | 1 | Stop bits (1 or 2) |
| split | string | No | "\n" | Character to split input on |
Common Baud Rates
Inputs
Data to send over serial. Can be string or buffer.
// Send string
msg.payload = "AT+GMR\r\n";
// Send bytes
msg.payload = Buffer.from([0x01, 0x03, 0x00, 0x00]);
return msg;Outputs
{
"payload": "$GPGGA,123519,4807.038...",
"port": "/dev/ttyAMA0",
"_serial": {
"baudRate": 9600,
"bytesReceived": 82
}
}Common Use Cases
GPS Module
Parse NMEA sentences from GPS
Port: /dev/ttyAMA0
Baud: 9600
Split: \n
Arduino Communication
Exchange data with Arduino
Port: /dev/ttyUSB0 (USB)
Baud: 115200
Level converter needed!
Modbus RTU
Industrial sensor protocol
Port: /dev/ttyUSB0
Baud: 19200
Config: 8N1
ESP32/ESP8266
AT commands or custom protocol
Port: /dev/ttyAMA0
Baud: 115200
3.3V compatible
Example: GPS Position Tracker
Parse GPS NMEA data and extract coordinates.
// Function node to parse GPGGA sentence
var line = msg.payload;
if (!line.startsWith('$GPGGA')) {
return null;
}
var parts = line.split(',');
// Parse latitude (ddmm.mmmm)
var lat = parseFloat(parts[2]);
var latDeg = Math.floor(lat / 100);
var latMin = lat - (latDeg * 100);
var latitude = latDeg + (latMin / 60);
if (parts[3] === 'S') latitude = -latitude;
// Parse longitude (dddmm.mmmm)
var lon = parseFloat(parts[4]);
var lonDeg = Math.floor(lon / 100);
var lonMin = lon - (lonDeg * 100);
var longitude = lonDeg + (lonMin / 60);
if (parts[5] === 'W') longitude = -longitude;
msg.payload = {
latitude: latitude,
longitude: longitude,
satellites: parseInt(parts[7]),
altitude: parseFloat(parts[9])
};
return msg;Troubleshooting
No data received
- Check TX→RX and RX→TX wiring (crossed)
- Verify baud rate matches device
- Ensure UART is enabled in /boot/config.txt
- Check permissions:
sudo usermod -a -G dialout $USER
Garbled/corrupted data
- Baud rate mismatch - try common values
- Check data bits, parity, stop bits (usually 8N1)
- Voltage level mismatch - use logic converter
- Ground not connected between devices
Permission denied on port
sudo usermod -a -G dialout $USER
sudo usermod -a -G tty $USER
# Log out and back in