🛠 Configure serial I/O on EdgeComp MS-U320

Objectives

This tutorial guides you through configuring the serial (COM) interfaces of the EdgeComp MS-U320. Unlike consumer PCs, this industrial mini PC features four dedicated COM ports (RS232/422/485), essential for communicating with PLCs, industrial sensors, or legacy equipment. The goal is to verify hardware detection and send an initial test signal.

Required Materials

• A BIOSTAR EdgeComp MS-U320 mini PC running Ubuntu 24.04 or Windows 11.
• An appropriate serial cable (DB9 male/female depending on your equipment).
• A USB-to-serial adapter for comparison or a serial terminal (e.g., PuTTY, Tera Term, or minicom on Linux).
• A target device (sensor, display, or a physical loopback test connecting TX to RX).

Steps

1. Physical Identification: Locate the four serial connectors on the rear panel. They are typically labeled COM1 to COM4. Ensure your cable is securely inserted.
2. Detection on Linux: Open a terminal. Serial ports often appear as /dev/ttyS0 to /dev/ttyS3 or /dev/ttyUSBx if adapters are used. Type the following command to list active serial devices:

dmesg | grep tty

You should see the Intel controllers associated with the COM ports initializing.

1. Permission Configuration: By default, only administrators can access ports. Add your user to the dialout group:

sudo usermod -aG dialout $USER

Restart your session to apply changes.

1. Install a Testing Tool: Install minicom to send raw data:

sudo apt update && sudo apt install minicom

1. Start Communication: Open COM1 (adjust as needed) with standard parameters (9600 baud, 8N1):

minicom -D /dev/ttyS0 -b 9600

If you performed a loopback test (physically connecting the TX pin to the RX pin of the port), type text: it should appear on the screen. Otherwise, send a command compatible with your connected sensor.

Verification

If the text you type appears in the terminal window, the port is functional. If you get a "Permission denied" error, ensure you are in the dialout group. If no ports appear in dmesg, check the BIOS to ensure serial ports are enabled (often named "Super IO" or "Serial Port Configuration").

Going Further

Explore the differences between RS232 (point-to-point), RS422 (differential, long-distance), and RS485 (multipoint bus) standards. The MS-U320 allows configuring each port's mode via the BIOS or specific card utilities, offering crucial flexibility for complex automation projects.