Homing sensors issue with parallel port BOB

See the "DC 3-Wire OR" configuration at the bottom of this page:
www.omron-ap.com/service_support/FAQ/FAQ00311/index.asp

It doesn't seem to work that way.
However my sensors are pnp nc, they should be putting out supply voltage until they trigger, shouldn't they?
I tryed with 1 signle sensor and that way it works (however i get en error if i try to "simulate" the homing process by hand, but that's not the main issue now).

PNP NC is a bit awkward.
Though with holes for targets rather than bumps it would still work.

My machines all tend to have holes for targets so that sensor failure is safer (It is also often quite a lot easier when you are burying the proxes inside the machine slides)

mmm
i'll do more experiments tomorrow (now it's 1.40AM here).
Thank you for your help!

Update:
the circuit of the first picture actually works, the problem is that when the final black wire is connected to pin 13 the leds behind the sensors dim instead of turning off completely, like if there is some current back feeding from the board to the sensors, but i can see a value change ti the pin value in the HAL Meter..
As a complete "electronic noob" i was thinking about putting a diode to avoid that. Does it make any sense?

Do you have any idea of where i could find a scheme for tat BOB?
I'm trying to understand what is going on by looking at how the various components are connected, but i'm quite lost.
I see that the bottom left pin of the optocouplers (that should be the cathode of the built in LED) is connected via a 1kOhm resistor to the input pins, and i can clearly measure a 2,3kOhm resistance between the top pin (that should be the anode) and GND, and this is exactly the opposite of what i was expecting...

edit:
For example i have a small board with 4 oprocouplers, and those are connected in a more common way.
The 2 input pins go directly into the 2 left pins of the optocpupler (with a 2,2kOhm resistor to protect a small led that shows the logic value of the input), while the 2 right pins are simply connected to ground (the bottom one) and to vcc with a 10kOhm pullup resistor (the top one).