@ Ano, The problem of a beam or GBD is it will not provide status of an open/closed, which would defeat any integrated automation and perimeter security. The unfortunate thing with sliders is they are VERY easy to lift off the track to gain entry.
You're looking at a contact for each movable panel, and that would be in each track so the door can bypass. most likely. I've done these a bunch of times. 3/8" contact, drilled next to the track on top (or bottom if needed) with a rare earth magnet on the moving panel. If tipping the panels down for magnet installation isn't possible, a small surface magnet/housing (rare earth and WG) on the butt of each movable panel also works.
The biggest item is making sure the bored holes in the aluminum track are square and straight and not oversized, with the contact secure or barely proud of the sill.