Below is the detailed schematic of the bidirectional input/output lines. 

Schematic:

Schematic of the bidirectional input/output

Notes:

The bidirectional input/output is not isolated and offers minimal protection.  

Applies to:

40-PIN DIO connector (I/O Expansion Connector) Pins 3 to 28, 33 and 34

Picture showing location of general input/output

CMD-4EX-SA J7 Pins 53-58 

Picture showing location of J7 58pin header