COM Port

System Node

You can access the COM port on the panel via /dev/ttyTHS0 By default, the baud rate is 115200.

Pin Definition

Pin	RS-232	RS-422	RS-485 (Two-wire 485)
1
2	RX	TXD+	TXD+/RXD+
3	TX	RXD+
4		RXD-
5	GND	GND	GND
6
7
8		TXD-	TXD-/RXD-
9

Disable Debug UART

In our pre-built system image, we disabled the debug UART feature of Jetson Xavier NX. If you built your system image, please remember to execute the following commands and reboot to disable the debug UART to properly use the COM port.

sudo systemctl stop nvgetty
sudo systemctl disable nvgetty

Using Debug UART

In our pre-built system image, we disabled debug UART on the COM port. If you want to use the debug UART, please use the following commands to enable debug UART.

sudo systemctl enable nvgetty
sudo systemctl start nvgetty

# confirm nvgetty status by 
sudo systemctl status nvgetty

Then you can use another computer to connect to the COM port and remember to set the baud rates to 115200. For example, if you connect to NRU-52S from COM 1 of another Linux computer, you can type the following commands to access the debug console.

sudo minicom -b 115200 -D /dev/ttyS0

Please also make sure the "hardware flow control" and "software flow control" are disabled.

Ctrl-A Z to open the menu. Type "O" for "Configure Minicom"

Select "Serial port setup"

Make sure "Hardware FLow Control" and "Software Flow Control" are disabled

Then you will see something like below while NRU-52S rebooted.

Hardware Configurable COM Port

The NRU-50 series has a hardware configurable COM port. The user can remove the bottom cover, and find a DIP switch to change various COM port settings.

RS-232 / RS-422 / RS-485 Configuration (DIP switch #2, DIP switch #1)

This mode is controlled by the DIP switch #2 (COM1_MODE1) and DIP switch #1 (COM1_MODE0).

	DIP Switch #1, Value 0	DIP Switch #1, Value 1
DIP Switch #2, Value 0	Loopback	RS-232
DIP Switch #2, Value 1	RS-485 Half Duplex	RS-422/RS-485 Full Duplex

RS-422/485 Termination (DIP switch #3)

For RS-422/485 communication, the RS-422/485 Termination option determines whether to enable/disable internal termination of RS-422/485 transceiver according to your wiring configuration (e.g. with or without external termination).

Slew Enable (DIP switch #4)

“Slew Rate” defines how sharp the rising/falling edge is for the output signal. For long-distance RS-422/485 transmission, you may set the “Slew Rate” option as “High” to improve signal quality.