the ports are there to simplify your cable harness if needed (for example you can continue from this ports to power other CONTROLLINO, use this port as common GND and power point, etc.). The ports are identical and are fully interconnected together.
Note: please take care, how you are measuring it, when the screws are not fully screwed, screw from the the top side has no contact. Try to fully screw and measure again ;-).
Sorry Johi, I asked another question via email related to one of your CTO reply emails to me a few months ago that there will be a new product with RS485 and Analog Output. But I am not sure why I did not get any reply until now both from the chat platform and email email@example.com I don’t want to put my email address on forum, so if you are from controllino maybe you can take a look at my registered email address and check email from me.