This connects to a Morse Paddles set or a straight Key. It depends on the "CW Keyer Mode" menu configuration to select if a paddle or a key is going to be connected.
Fig. 5 - Paddle Connector
Simply consists of a "Normally Open" NO switch between GROUND and DAH. Only 2 pins are needed.
Fig. 6 - Straight Key cable
This is like two NO switches, but sharing the ground pin. 3 pins are needed. Dit and Dah can be reversed via "CW Paddle Reverse" menu option.