A 14-position terminal is used for GPIO and Serial connections.
The serial data port uses 3 (including common Ground) of the 14 pins configured as Data Communication Equipment (DCE). RS485 uses two pins.
Serial data ports on most computer equipment are configured as Data Terminal Equipment (DTE). In some cases, it may be necessary to insert a “null modem” or “gender changer” in the serial data line in order to correctly connect between the devices.