Wiring up the Alarm output on Leadshine AM882

[m_c]

Given that they're NC when not activated, if you want to connect them through a single pin, then you'll need some way to invert the signal.

There are various options, however the one that involves reasonable size components is to use a small relay for each sensor.

However, looking at the specs for those sensors, they are far from ideal, given detection distance is listed as 5mm +/- 10%.
A slot type sensor is far more accurate, such as Optical End / StartStop w. mounts- For CNC, Reprap and laserengraving machine | eBay