Many if not most roller-coasters since the 1970s have been controlled by PLCs. Allen-Bradley was involved and pushed to continuously provide faster and higher capacity PLCs for this application area.
Industrial technicians aren’t software engineers and in many cases are mechanics. Ladder logic is easily taught to these techs which allows the tech to troubleshoot low to medium complexity problems on their own. The engineer(s) are probably not on-site or even in-country at this point in time.
Pneumatic controls are still heavily used in nuke plant controls due to the slow, expensive process required to qualify any new equipment for that environment. Utilities keep equipment forever, so you’ll see a mix of technologies still in-use.
James
