The FES Bridge is a device which connects together a FCU CAN bus and a LX80/90XX system RS485 bus. On the FES side, the FES bridge must be connected to the CAN bus as described on the schematic below. This cable is not supplied with FES bridge, it must be soldered directly to FCU plug.
On the RS485 side there is a spring connector which can be wired to a DB9 (RS485) as on schematic below, connected to the RS485 splitter, or simply connect four wires parallel to remote stick spring connector on the RS485 splitter. Indication gauges can be created with the LXStyler or LAYOUT function. Just connect correct the coloured wire to the appropriate pin. On the other side it should be connected to the CAN bus (DB9) of the FCU. On this side 3 wires are needed to be soldered to the correct pins.