There are actually 2 no. of similar connector on the Power Unit. 1 is for your Temperature Probe, the other Water Level Sensor. Unless you have more probes/sensors, then you can purchase a Water Level/Temperature Interface which gives you another 2 slots... I bought another Interface Coz I plan to have another Temperature Probe soon... perhaps to record room temperature
But again, I have not connected my Water Level Sensors yet. So can't confirm the above for sure. I will connect tonight (if can't get movie tickets ) Stay tuned!
I will do a proper review specifically on issue this weekend.