Missing kernel driver for WCH CH348 (Waveshare USB TO 8CH RS485)

[bromeoo-lab]

Describe the issue you are experiencing

Describe the issue

I am using an industrial-grade "Waveshare USB TO 8CH RS485" converter module connected via USB to my Home Assistant hardware running HAOS.

The system successfully detects the USB hardware structure and displays the device name in the hardware info list. However, it completely fails to initialize or create the actual virtual serial communication ports (/dev/ttyUSB0 through /dev/ttyUSB7).

This 8-channel board is built on the newer WCH CH348 high-speed USB-to-UART bridge chipset. The required Linux kernel driver module (ch341 / ch348 support) is currently missing or disabled in the HAOS kernel build configuration.

Hardware information

• Device: Waveshare USB TO 8CH RS485
• Main Chipset: WCH CH348
• USB Vendor ID: 1a86 (QinHeng Electronics)
• USB Product ID: 55b8 (CH348 USB to 8UART)

Expected behavior

The Home Assistant OS kernel configuration should have the driver support for the WCH CH34x/CH348 series enabled by default, so that all 8 independent RS485 channels on this industrial DIN-rail module can be correctly exposed to the system as separate /dev/ttyUSBX serial interfaces.

These multi-channel Waveshare modules are becoming highly popular for home automation installations to aggregate multiple Modbus RTU, smart meters, and inverter lines into a single USB port. Thank you!

What operating system image do you use?

yellow (Home Assistant Yellow)

What version of Home Assistant Operating System is installed?

Home Assistant OS 17.3 (Kernel 6.12.75-haos-raspi)

Did the problem occur after upgrading the Operating System?

No

Hardware details

Home Assistant Yellow (aarch64)

Connected USB Hardware requiring driver:

• Device Name: Waveshare USB TO 8CH RS485 Converter
• Main Chipset: WCH CH348 (High-speed 8-port USB-to-UART bridge)
• USB Vendor ID: 1a86 (QinHeng Electronics)
• USB Product ID: 55b8 (CH348 USB to 8UART)

Steps to reproduce the issue

1. Connect the industrial "Waveshare USB TO 8CH RS485" converter module to any available USB port on the Home Assistant Yellow.
2. Go to Settings -> System -> Hardware -> All Hardware.
3. Observe that the OS successfully detects the USB topology and shows the device identity structure on the USB bus.
4. Check the /dev/ serial port mapping list. No virtual serial interfaces (/dev/ttyUSB0 to /dev/ttyUSB7) are initialized or mapped for this hardware because the newer WCH CH348 multiplexer driver is missing or disabled in the HAOS kernel build configuration.

Anything in the Supervisor logs that might be useful for us?

The hardware is successfully seen via the USB bus topology, but the driver registration is completely skipped as the ch34x/ch348 multiplexer module driver is absent in the kernel. No specific error trace is present in the Supervisor logs; the serial interfaces are simply not exposed to the system.

Anything in the Host logs that might be useful for us?

From Supervisor logs:
2026-05-17 22:48:49.659 INFO (MainThread) [supervisor.hardware.monitor] Detecting add hardware /dev/bus/usb/001/003 - None

The OS detects the hardware addition on the USB bus but initializes it as "- None" because the required CH348 driver module is missing in the kernel configuration.

System information

No response

Additional information

No response