Conductivity Probe: Anyone know the Pinout or reason behind 4 pins on PM2 Cond port?

[Quinnchero]

Title pretty much sums up the question. Why are there 4 pins on this port? I assume it was for conductivity probes with built in temp compensation. And yet they don't sell that style probe as an option. I am trying to find an aftermarket cond probe that is more reliable than what Neptune sells. It is good...I want better. But 95% of all higher end probes require BNC connections. I have found adapters but all of them split the mini 4 DIN adapter into two BNC connections. I want to know essentially which one is correct to use and how to determine that without possibly damaging the PM2 module. So which two pins are the required connections for a cond probe. Unless the other two do something else entirely different that measure temp.
Is anyone using alternative Cond probes? For example from Atlas Scientific?

Thanks for the help!

Q