Finally, you need to wire the board with the appropriate connectors.  The board is labeled with a host side and a BrainStem side.  We start with the host side. 

Overview showing the board connections.

Each platform has a unique connector and pin arrangement.  The proper three connections (GND, HTX, and HRX) need to be made with your platform's connector.  The HTX and HRX symbols are from the perspective of the host computer. 

Common platform connections.

The BrainStem side of the board is next.  This involves four connections in this order on the BrainStem serial connector: GND, STX, Vcc, SRX. 

BrainStem serial outputs.

All four wires must be soldered in on the interface cable board with the marked wire on the ribbon cable connecting to the ground connection. 

The completed board cable.

Related Links:

Building the Serial Interface Kit - Part 1: Installing the LEDs