Re: IoT?
<quote>I think you missed the point, he's talking about replacing the older hardwired control and monitoring systems using hundred of wires for all the discrete connections, with systems where the information is passed over a network connection with just a few wires.</quote>
and
<quote>Large hardwired control and monitoring systems use a LOT of wires, and in a large plant they can be long ones at that.</quote>
I know of what you are talking about.
Having worked as an electrician in a past life, I was once given the opportunity to pour over the control schematics for an elevator. This was back in the day when the control mechanisms were RELAY based. The cable running from the elevator cab to the control box had more than 70 conductors. There were more than 100 conductors running from the in shaft wiring of the call buttons and direction lights to the control box, and then an equivalent number from the control box to the floor number display over each ground floor door. What made this even more problematic was that all of the conductors were of the same color, with only a printed number to identify each conductor.
As integrated circuits became cost effective, I could see a transitions from discrete wires to discrete logic performing the same functions. In an elevator those functions would be floor number display, and floor number selection in the cab. On each floor, you have the up/down call buttons and the up/down direction lights.
Transitioning individual lamps to a numeric LED floor display would be the 'easiest'. You could use simple BCD to 7 segment decoders in conjunction with a 7 segment LED. A single digit will get you up to 9 floors, a 1-1/2 digit will allow up to 19, 2 full digits will get you to 99. All you have to do is just output the floor number as serial data. This would require only 4 wires (power, ground, data+ and data- assuming a balanced data circuit. Hey, doesn't that somewhat resemble a USB 'buss'???)
How to deal with the call buttons on each floor. simple, IF at each floor, the call buttons had some discrete logic that would pass back the button status, not unlike the way the keyboard in front of you is polled by the computer it is connected to; one could use only 6 conductors to service a stack of call buttons. The electronics located at each floor would be field programmable to respond to a specific 'address' sent serially over a TX pair of wires. The status could be sent back as UP_BUTTON_PRESSED or DOWN_BUTTON_PRESSED over two wires, and then only require power and ground to operate. The direction lights over the doors could be left alone.
The end result is to reduce the clusterfuck of wires to just a few.
Biting the hand that feeds IT
