connect canbus to ownice head unit the correct way.

Hi All
I did buy a ownice C500+ head unit.
this has a canbus TX and RX (does not say high and low)
it came with a ISO harness wire loom and a canbus decoder.
There where lots of wires and connectors that i dont need or use.
When I did cut away all the wires and connecters that I don need.
when all are gone i noticed that the canbus decoder had only 6 wires left.
Plus and minus for the power.
2 wires to the Canbus of the car
2 wires to the Canbus Ownice head unit

My questios is now, what is this canbus decoder still doing?
Or can i just connect the canbus of the car direct to the head unit?

Any danger to test that?

Frank (Dutch)