In our smart port wires I understand there is 4 pins, two of which are 12V and GND which are the red and the black. Do you know what the other two pins (green and yellow) are for?
They could be used to send input and output to the brain like for the vision sensor
Typically a setup like this is for doing I2C protocol (Wikipedia link), where you have a voltage source, return/common, and then the other two lines are used for the clock pulse and two-way data line.
While I don’t know for sure that it’s I2C protocol in use here, it’s likely something very similar.
V5 smart ports use RS485, and IIRC red/black is not power/gnd,
Which wires are what actually depends on how the cable is made. These two posts show what each pin does for a particular crimp orientation:
If your wires are crimped reverse of this, then reverse the pin assignments.