Without a schematic I’d guess it to be an open collector interrupter. Used a home brew version of this on my little CNC machine. Changed to hall effect after junk from the spindle flew it’s way through the interrupter and triggered an error.
I would simply pull the pin to ground, configured as normal. It should detect that and probably fault if it’s trying to home.
Some of these were not a ‘wired or’ configuration, although from the photo, it could be… I read the link, which didn’t say much. There were a couple of comments, translated from German, and indicated he had a problem because the output signal went the wrong way.
It’s an open collector, but I’d guess the resistor and led are on the b+ side with the emitter to ground. So if the output is off the collector and no interruption of the IR beam the photo transistor conducts pulling the output low. This would be the normal state (similar to ‘NC’ on a mechanical switch,) the opposite of what most limit switch inputs are looking for. You can switch what most controllers are looking for but you lose the ‘wired or’ configuration benefit.
I built a few sets of optical and (digital) hall effect limit switches. They worked by a pair of magnets on the table for limits at both ends of the X and Y axes. Pretty simple and straightforward…
However on the Z axis I had an issue with real estate of where to mount the 2 hall switches, 2 sets of cables and the two magnets. I prefer to have the least amount of ‘moving’ wires. I finally placed one hall switch in the center of the z axis and magnets on each end, simulating the switches on each end.
Here’s some pictures
The part holding the magnets no longer uses tape to hold the magnets, but has been modified to look more like a slot you can roll the magnets up and down for a more precise adjustment and more mechanical stability.
The previous mounted optical interrupters required an inverter board attached since it’s output was low normally. On the Z axis I used one interrupter that spanned the entire Z axis, eliminating the need for an inverter and dual switches. Mechanically inverting.