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Certainly PLC's are used, and certainly there's a microcontroller in them: but they're also certainly not running anything more than a very simple embedded bit of software in a very tight loop.
Yes, PLC's simplify things immensely, and can often make things much cheaper once things start getting complicated and allow things to be reprogrammed as needed, but they don't require even anything as complicated as QNX, or as much RAM: they've been around and used before QNX was around, in such places as car factories. PLC's have a minimum amount of memory, only as much as is required to hold the current state of all the I/O hardware and the limited number of timers and such, because they don't need anymore than that.
Put in the original context of "I wouldn't use an elevator with anything else" even with the more sophisticated elevators (how many use QNX?) causes options to be extremely limited.
FYI, yes, I've programmed PLC's in industry.
What is your building control system/application written in? Building I work in is centrally controlled, from the vents to the window shades to the elevators to the escalators to the moving sidewalks to surveillance... there is only 5 flights of stairs and I do usually use them just for my health but if someone were to say, "QNX or nothing", then I would take it to mean nothing is perfectly acceptable which would include those antiques.




Member since:
2005-07-11
I can't imagine an elavator in a large building that didn't use a microcontroller or PLC.
How do you get your electromechanically controlled elevator to look at 10 requests from 10 different floors for up or down direction and schedule them appropriately with hardwired relays?
I'm sure it's possible with lots and lots of boolean simplification and cabinets full of hundreds of relays, but each relay is a mechanical failure point, and the project would be ridiculously expensive. I can buy 3 or 4 relays for the same price as a cheap PLC that can emulate thousands of relays.