PR55-48 Sensor Power Polarity

I received a unit that puts out -16V when polarity is red(+), black (-).
The red wire was in the terminal block position closest to the sidewall of the enclosure.

Is this normal or was this a quality escape?
Normally, I’m used to the red wire being positive. Threw me for a bit of loop because I could not for the life of me figure out why I couldn’t get my sensor to work.