08-13-2025, 01:44 PM
Hello, friends.
Help: Connect RS485 I/O modules to the Raspberry Pi 4 Relay Board (Server Mini) + Home Assistant OS
Hardware
Goal
What I’ve found / tried so far
Help: Connect RS485 I/O modules to the Raspberry Pi 4 Relay Board (Server Mini) + Home Assistant OS
Hardware
- Controller/board: KinCony Raspberry Pi 4 Relay Board / Server Mini (link: https://www.kincony.com/raspberry-pi-4-relay-board.html)
- Modules I want to add: KinCony RS485 I/O modules (link: https://www.kincony.com/rs485-io-module.html)
- Planned system: Home Assistant OS (not Raspberry Pi OS), running on the Pi inside the board
- Use case: Wired wall switches and I/O around the house → one RS485 bus, multiple modules, stable & scalable for many installs
Goal
- Daisy-chain several KinCony RS485 I/O modules to the Server Mini’s onboard RS485.
- Control/monitor them from Home Assistant OS (HA Modbus if possible).
- Best-practice for addressing many modules (bulk provisioning) without connecting a laptop each time.
What I’ve found / tried so far
- The board exposes RS485 via the Pi’s UART (I see pins marked GPIO14 = TX, GPIO15 = RX on documentation/pins).
- On Home Assistant OS, I cannot just edit /boot/config.txt like on Raspberry Pi OS, so I’m not sure about the correct way to enable the UART for the onboard RS485 under HA OS.
- I tried using generic HA Modbus config but I’m not 100% sure about the device path (e.g. /dev/ttyAMA0, /dev/ttyS0, or /dev/serial/by-id/...) and serial parameters (baud, parity, stop bits) for KinCony’s RS485 port on this board.
- I previously attempted the old rpi_gpio integration for direct GPIO, but HA OS doesn’t include that — so I want to use RS485/Modbus properly instead.