Connecting SICK WL150-P430 sensor to Arduino UNO

I am constructing a setup that will be able to read values from a SICK WL150-P430 sensor through an arduino uno board. I was hoping to use the digitalread() of the arduino to read the value of the sensor but being a beginner at electronics I am not entirely sure how to connect all making sure not to fry anything. The sick sensor has 4 wires. It requires a 10-30vdc to power it. I am taking care of this by using an external power supply that gives it around 12v. The sick sensor has two other wires blue/black. The voltage being output between these wires is 3,78V measure with a multimeter. I am powering the UNO board from USB from the computer.

Is it safe to connect the black lead to a digital input on the arduino or do I have to construct some sort of voltage devider. And should the negative wire of the sensor connect to the the ground on the arduino breadboard or the powersupply’s ground?

I attached an image make it more clear.

https://www.sick.com/media/dox/5/25/825/Operating_instructions_SENSICK_WL150_en_fr_de_da_nl_it_zh_pt_es_IM0003825.pdf

Anybody?

it might be safer to use the toggled voltage 3.78 signal as an input to a comparator circuit ( +) terminal and letting the (-) terminal triggered at that same voltage. the comparator output can be provided to an semiconductor opto -isolator before the Arduino board ( this way the Arduino circuit and everything connected to it is safer ....just a thought from a previous circuit I did when I was younger.