First, mce hydro, easiest to troubleshoot, Otis 211 units are the best in the business!! Otis guys tell me that many years ago, Otis had no money to produce a new controller, so they just kept improving the 211.....I agree they did the right thing. Elevator controls serial link stuff is a joke!! Nothing but problems and repeat calls, makes us look bad. Tech support stinks!! As far as I am concerned, Schindler stuff is the bottom of the barrell. Lots of sharp edges, none of the sheet metal deburred. Way too many door operator faults, causing call backs. Customers that we take on Schindler units complain about schindlers service. They don't show up, don't support warranty units. I went to a call back with entrapment, customer called from elev. phone and Schindler office said thay might get someone there in a few hours! I got the man out, 6 weeks later, they called us to fix the unit...Schindler never showed up...oh we'll, it makes money for us....Schindler installs the cheapest JUNK....in the U.S. ..