Follow-up thought - if someone were to develop a door operator that could speak the Otis serial/multi-drop (and maybe even CAN) door protocols, is this something that non-Otis companies would buy in situations where they were already maintaining the original Otis equipment under contract?
This might allow them to continue to maintain these units rather than paying for another newer Otis door operator like a Glide A that locks them into buying even more Otis spare parts (or locks them out if it requires an Otis mechanic with special tools). If the building owner decided to modernize the controllers (which would be an expensive "nuclear option" to get away from Otis proprietary equipment), that Glide A might not be compatible with the next control system.
A lot of those older Otis controllers like E411 seem to "just work" for many years with some TLC, but door operators inevitably wear out mechanically or the drive motors and electronics die from millions of open-close cycles.
