EFIS Expansion Connector

I must be missing something since everyone else can figure out how to connect the ARINC 429 module to the EFIS Expansion Connector, but I am struggling.

The manual says the pin arrangement for the EFIS Expansion Connector is (pg 88):
1 SERIAL #4 - TX
2 SERIAL #4 - GROUND
5 GROUND
6 SERIAL #4 - RX
9 +5V DC (350mA max)

The ARINC 429 Main Cable schematic diagram (pg 111) shows the EFIS Expansion Connector as:
1 SERIAL #4 - TX
2
5 SERIAL #4 - GROUND
6 SERIAL #4 - RX
9

I confused as to which is the Serial Ground. Please clarify the connections to the EFIS Expansion Connector.

Thanks...

Pin 2 and Pin 5 are connected to the same place in the screen, they both are ground.