UART

Connect to UART serial ports

Connect to UART serial ports on Lagerboxes for serial communication with devices.

Syntax

lager uart [NETNAME] [OPTIONS]

Arguments

Argument	Description
NETNAME	UART net name (optional if default is set)

Options

Option	Description
--box BOX	Lagerbox name or IP address
--baudrate RATE	Baudrate (e.g., 9600, 115200)
--bytesize SIZE	Data bits (5, 6, 7, 8)
--parity MODE	Parity: none, even, odd, mark, space
--stopbits BITS	Stop bits (1, 1.5, 2)
--xonxoff / --no-xonxoff	Software flow control
--rtscts / --no-rtscts	Hardware flow control (RTS/CTS)
--dsrdtr / --no-dsrdtr	Hardware flow control (DSR/DTR)
-i / --interactive	Enable input mode for typing
--opost / --no-opost	Convert \n to \r\n on output
--line-ending MODE	Line ending: lf, crlf, cr (default: lf)

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Usage

Read-Only Mode (Default)

# Monitor serial output
lager uart SERIAL1 --box my-lager-box

# With specific baudrate
lager uart SERIAL1 --baudrate 115200

Interactive Mode

# Type commands and see responses
lager uart SERIAL1 --interactive

# With specific settings
lager uart SERIAL1 -i --baudrate 9600 --parity none

Get Serial Port Info

# Show device path for a UART net
lager uart SERIAL1 serial-port

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Serial Configuration

Baudrate

Common baudrates:

• 9600 (default for many devices)
• 19200
• 38400
• 57600
• 115200 (common for embedded development)
• 230400
• 460800
• 921600

Data Format

Setting	Options	Default
Bytesize	5, 6, 7, 8	8
Parity	none, even, odd, mark, space	none
Stopbits	1, 1.5, 2	1

Flow Control

Type	Options	Description
Software	--xonxoff	XON/XOFF characters
Hardware	--rtscts	RTS/CTS pins
Hardware	--dsrdtr	DSR/DTR pins

Flow control types cannot be combined.

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Line Endings

Mode	Sequence	Use Case
lf	\n	Unix/Linux
crlf	\r\n	Windows
cr	\r	Legacy systems

Use --opost to automatically convert line endings on output.

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Supported USB Serial Adapters

The following USB-to-serial adapters are automatically detected and supported:

Adapter	VID:PID	Description
Prolific USB-Serial	067b:23a3	Common USB-Serial adapter
Silicon Labs CP210x	10c4:ea60	Popular embedded dev boards
FTDI FT232R	0403:6001	Single-channel USB-Serial
FTDI FT4232H	0403:6011	Quad-channel USB-Serial
ESP32 USB JTAG/Serial	303a:1001	Built-in ESP32-S3/C3 USB

These adapters are automatically recognized by lager instruments and can be configured as UART nets.

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Device Path Support

UART nets can reference devices two ways:

USB Serial Number (preferred):

Net configured with USB serial number
Automatically resolves to correct /dev/ttyUSBx

Direct Device Path (fallback):

# When adapter has no serial number
lager uart /dev/ttyUSB0 --baudrate 115200

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Examples

# Basic serial monitor
lager uart DEBUG_UART --box lab-gw

# Interactive shell with common embedded settings
lager uart CONSOLE -i --baudrate 115200

# Legacy device with specific format
lager uart LEGACY --baudrate 9600 --bytesize 7 --parity even --stopbits 2

# With software flow control
lager uart MODEM --xonxoff

# Windows-style line endings
lager uart TERMINAL --line-ending crlf --opost

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WebSocket Connection

The UART command uses WebSocket for communication:

• Provides real-time bidirectional data
• Supports both read-only and interactive modes
• Automatically reconnects on connection loss

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Troubleshooting

Device Not Found

# List available instruments to find UART devices
lager instruments --box my-lager-box

# Check if USB serial adapter is connected
ssh lagerdata@my-lager-box 'ls -la /dev/ttyUSB*'

Permission Denied

# Ensure udev rules are installed
lager update --box my-lager-box --yes

No Output

• Check baudrate matches device
• Verify TX/RX connections
• Try interactive mode to test input
• Check flow control settings

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Notes

• Interactive mode requires a TTY terminal
• USB serial numbers are truncated for display
• Default net can be set with lager defaults add --uart-net
• Connection retry logic handles temporary disconnections