Remark: Current board RS485 port is with RS422 signal.
SO-DIMM 200pin Board-to-Board Connector
The daughter board of the SBC9261-I is connected to the mainboard via a SO-DIMM 200-pin connector, which is mounted on your mainboard. Signals routed to DIMM 200-pin please refer to the file: MINI9261I_connector.pdf