DUPLEX elevator call logic - how does THAT work?

[@mrmattandmrchay]

THANKS FOR JOINING THE PREMIERE EVERYONE - 150 viewers in the end I think! Another record. Soon, I'll have 100'000 people in the premieres HAHA (in 100 years time - just a joke!)

[@jp-alarms]

mrmattandmrchay I will upload the video on my new air tool hopefully you get time to watch it I would turn your volume down haha

[@Dana_Danarosana]

You've just brought me back to a hotel stay I had as a little kid 40 years ago. An older (even then) 12 story 2-car Otis setup had the left car broken down all weekend. After noticing how long we had to wait for a down call even when they didn't seem to be coming, I pressed 🔼 and got the working car to respond right away. I kinda had this sort of figured out as a young nerd 40 years ago... but as a now OLD nerd, I'd completely forgotten this story until right now. Thanks for the formal explanation... and allowing me to pretend I'm 9 years old again for 10 minutes! ☺

[@Speeddemon3]

You really know your stuff! I'm just thinking how many times did the first innovators have to go back to the drawing board to add relays over scenarios that weren't thought of until they happened. Those engineers are mad geniuses!

[@4WDAUTO-y8o]

Your videos are amazing I have always loved the way you explain how the complex stuff works into a way that I can sort of understand

[@mrmattandmrchay]

Thanks Sigma, glad you like them!

[@dykodesigns]

Splitting the lifts up in dedicated directions is pretty clever in it’s simplicity. Seeing this, it seems like the obvious solution but I have never thought of it beeing that simple. Always thought it was more complex. Reducing complexity in the controller design must have been quite common in the sisxties and could kind of explain some odd designs in lift configurations. I know of some appartment buildings with 13 floors and two lifts but only have 5 stops. Each lift runs individually like a simplex system and serves a different set of floors. One for the even floors and one for the odd floors. I once filmed such a setup in an appartment building that had split level floors where lifts stopped at stair landings between the main floors. Really odd design but very clever in keeping the lift design simple.

[@passacaglia28]

My apartment building has three elevators. They seem to be random to this uneducated observer. For those cars where people are moving in/ out, or maintenance is using, there is an "Independant Service" mode where the elevator car only works between two floors and ignores all other calls. If someone holds the door-open button, or physically holds the door open for too long, the car "beeps" and broadcast a message stating that one should "stand clear of closing doors". In the past, this latter scenario has often caused the car's logic to become confused and even temporarily go out of service. I believe that has been fixed for now. The building in which I live has seventeen floors and houses many university students. This means they are in frequent use. Our elevators say "Westinghouse" on the thresholds. However, they are often serviced by Kone. Once, I saw a Fujitec van out front. I don't know where I'm going with all this, but your videos have helped me to become more aware of what goes on "under the hood (or bonet?) ".

[@pineappleroad]

Ive seen a modern lift system dispatch both lifts to the same call before (Although that system had a glitch or something where one of the lifts would randomly go to the ground floor every now and then, or re-open if already on the ground floor)

[@QuarioQuario54321]

From what I can tell this is only their lower end general installs. Their high-end Autotronic system which was mostly found in larger buildings or for large sets could change regularly.

[@lbsiuk]

Great video, Matt. That was very informative. I think that my favourite lift video out there is the two you made of the DMR system.

[@sgbuses]

I recall in my childhood, the old Fujitec residential elevator only had one call button that has a fixed direction (up on the first floor, down for the rest, never both). The Fujitec going up will always ignore any calls going up, and if the twin car is below the floor it never gets called. Always had long waiting times for the only one lift coming down from 20 floors towards the 4th floor, while the other sits idle at the 1st floor! I guess something similar with cost-saving is going on here as well.

[@38911bytefree]

Brilliant as usual. Many thanks for your time and effort. But you can go further with relays. Someelse noted on your motor room tour (it was a parking building) with 2 express lifts, that its dispatcher was a 4 zone system, and the cabinet was just relays. Its interesting to note that no one has the perfect algorithm for multiple lift buildings. A big manufacturer (dont recall what) used statistics and data from the id cards that employees use to enter in the main lobby to enhance the lift usage in rush hours. My statistics professor worked for for real wolrd cases also. He was aked to make a model of the people trafic on lifts on a new building. They input this model somehow in the controller. Things get insane complex with so many lifts ans still no one has an accurate answer. Each building is different.

[@markh5210]

A system like this will encourage people to press both buttons to call the lift as it genuinely can make their journey quicker. It also relies on there being a fairly even flow of passengers, at times where most users are wanting to go in the same direction then one of the lifts will be underused.

[@upanddownadventures]

One elevator is assigned to up calls, the other elevator is assigned to down calls. In many cases, the "UP" elevator will respond to UP calls, the "DOWN" elevator will respond to DOWN calls, with a few exceptions. 1. If an elevator is already on the landing, the call buttons are connected to call the elevator that is already at the floor. 2. If an elevator stops at a floor due to a car call, and is going in the same direction as a hall call on that floor, it will cancel the hall call, even if it isn't the assigned elevator. 3. If the assigned elevator is held open (either deliberately or due to a mechanical fault with the doors for example), after a set time the call buttons become connected to the other elevator. 4. If an elevator fails to answer a call (i.e. it breaks down), after a set time, the call buttons are connected to the other elevator. 5. If an elevator stops at a floor with up & down calls, and is idle (no other calls assigned to that elevator), BOTH calls will be cancelled. Is this a pretty complete description of the logic of this system? I'm curious what would happen if for example, you press both the UP & DOWN buttons, and the UP elevator gets to the floor first, BOTH calls are cancelled, and the DOWN elevator was moving towards a call that was cancelled, and is otherwise idle. In that case, the DOWN elevator could either stop immediately between floors, and probably not open it's doors (I suspect Otis controllers don't have a provision for this), stop at the very next floor and probably not open it's doors, stop at the floor where the cancelled call was (and either open or not open it's doors), or stop at the last floor in the direction of travel (and either open or not open it's doors). Is the system described in this video used on a two speed AC installation, a DC installation with motor generator, or both? It certainly could be used for either, but not sure if a more complex and more efficient system would be used for DC installations. I wouldn't be surprised if some larger relay-logic installations (perhaps with 4+ elevators) used a more complex but more efficient system, as in those cases a more efficient system may be worth it, assuming it is reliable, if the alternative is to have more elevators, and less usable space in the building. I'm hoping to visit some buildings with Otis duplex systems probably running on relay logic soon. They probably are DC elevators with motor generators. If I can, i may test some of these things.

[@tilmanluther1887]

Mrmattandmrchay I like your videos explaining how elevators worked, and how they do now. Much more cooler than a computer with windows 10

[@mrmattandmrchay]

FIRST COMMENT is all mine!! :D

[@jonathanschaffer5758]

third belongs to me.

[@MichalM]

LOOOL

[@jonathanschaffer5758]

@@aidanstandingI don't get it

[@LondonAndSouthEastTransport]

@@GenericLifts hi

[@GenericLifts]

@@LondonAndSouthEastTransport hi

[@Josh.Davidson]

Absolutely amazing, really enjoyed this. Thank you!

[@mitchellj5212]

Can you remake this video but this time with double decker lifts and why sometimes it auto locks the lower lift but keeps the upper lifts unlocked and vice-versa

[@upanddownadventures]

Am I correct that in for example a 10 floor building (with the lowest landing being the 1st floor, elevators serve 10 landings), the UP car is on floor 1, the DOWN car all the way up at floor 10, if someone presses the DOWN button on floor 2, the DOWN car will come despite the UP car being much closer to floor 2? Am I correct that this is quite inefficient? At some point maybe I will do some experiments on multi-car (group) relay logic elevator systems to see how they behave. I assume solid state controllers would often work in what seems like the more intuitive way (if all elevators are idle, closest car will answer a call), but I could be wrong.

[@mrmattandmrchay]

Correct. So if the CALL=2, then... CAR1 compared with CALL (1-2) = Distance: 1 CAR2 compared with CALL (10-2) = Distance: 8 We are now preforming calculations. Imagine doing this using relays! Is kind of possible, but now you are adding far more relays. More relays means more cost, more things to go wrong and more complexity for someone to be able to fix it. And is it really neccessary? When a customer doesn't want to pay for it, and they just want a method of getting people from floor to floor, they aren't bothered if a lift has to travel further occasionally. It would cost more to have an engineer trying to fix the lift due to the extra complexity. Please bear in mind, this video is about OTIS. The Express Lifts system didn't work the same way. I may do another video at some point explaining how the Express systems worked. But as time went on, Express did manufacture a 'closest lift' dispatching system using resistors, which maybe I'll cover in a future video.

[@VarunGupta3009]

Really good explanations...!

[@mrmattandmrchay]

Thank you!

[@marksmith-ew7ir]

I have worked in building where there was three lifts serving 18 floors and you can control it by computer lots of relays to each cabinet but is shindlers

[@okbridges]

This video answers a lot of questions! This is the exact setup that I have the parts to, and 5 sheets of wiring diagrams of. Now I want to make both selectors on my reconstruction run just to run these scenarios and watch the relays click. Do you have any estimate on the power consumption of just the logic relays? Since I am going to use a 1/2 HP gear motor to operate each selector, will not need to use the large power relays that fed the 25 HP traction motors I have to determine if I can salvage the original DC power supply or not, so if I end up building a power supply I am worried about current.

[@BigKitty1011]

Well it depends on how many components will be using power simultaneously. I can not be certain, but most otis relay coils run off of 120V and will use around 30 - 100mA of current. But the real power consumers will most likely be the motors. If you plan on using the original DC power supply, a few considerations will be needed. If the original DC supply is a MG unit, you will definitely need to worry about the current as MG units are very power hungry. Honestly using a full wave/bridge rectifier with a smoothing capacitor will be easier and more efficient than a MG unit. Calculating this out and after making a few assumptions I can say with confidence that you will need at least 30A to run the components. It may not sound like a lot, but here is an important thing to remember! Often times, these old otis elevators connect relays together in series, which means that you need more voltage than the 120VAC you get from a typical house plug. I have seen otis elevators that use up to 600VAC in order to run the components in a proper manner. If you truly want to hook these components together, It would most likely be a direct wire connection as no elevator can be run by just plugging it into a wall. So you would need to go into your main lighting box and bring a large wire towards your display, then a 3 phase converter would probably be in order. A transformer afterwards to convert the 120V/208V into whatever voltage you need to run any series'd relays. It sounds like a lot of work! But if your up to it, then I won't stop you. I would recommend looking at similar elevator systems and seeing what they use for an overcurrent device rating. I can't say from experience, but I would estimate that most elevators use around 30A - 50A of breaker/fuse protection. Keep in mind that this assumes that the elevator is of newer type and does not use giant gearless motors (some gearless motors can suck over 100A from the grid!). I wish you the best of luck getting them up and running and I look forward to seeing if you make a video on it! :)

[@okbridges]

@@BigKitty1011 Thanks for your reply. I do not have the MG sets or the traction motors. My "elevator" will be a 1/2 hp gear motor connected to the pie-plate selector unit to simulate elevator car movement thru a 6 story building. 30-100ma current per relay for 10 or 15 relays dawing current at once sounds manageable for a 120V DC power supply that can be built and plugged into a 20A outlet.

[@ElPeppito]

8:32 jesus fucking chirst almost had an heart attack

[@BigKitty1011]

Very informative! However if I may ask. What about a triplex system? How would the elevator controller dispatch elevators in such a system? I would believe it would involve giving certain elevators certain calls on certain floors right?

[@VOLTRONDEFENDER4440]

This is like the modern elevators if one is broken it becomes a single bay system instead of multibay system

[@MichalM]

THAT WAS EPIC!!!

[@GenericLifts]

IKR

[@JamesPetts]

Very interesting.

[@DevAqua]

What happend to the saudi arabia lifts tours also I saw an old Otis lift at dammam/saudiarabia it's scary and also unstable

[@hardikrajpal2410]

So we're not gonna talk about the James Bond music in the background?

[@christopher-2000]

Awesome

[@Trizo]

Why are your up arrows red and not green? lol

[@garfieldandfriends2]

It's really annoying how the one that is coming towards your floor just went past it while I have to wait 1 additional minute because the second lift is still 2 floors away and the logic decides to assign second lift to my floor instead. (considering both are going down, for example, and I'm also going down)

[@lzh4950]

Sometimes a lift that stops @ your floor gets physically full because too many passengers want to board it, but its weight sensor still doesn't detect enough mass for the lift to register as 'full' in its computer, so there's the anguish where (a) neighbouring lift(s) that's passing by your floor is then programmed by the computer to skip your floor because it still doesn't think that more lifts are needed to serve that floor

[@BigD751]

My place has 3 elevators 🤯

[@someoneelse9637]

This makes some sense in buildings where up and down calls are somewhat evenly distributed, but how about a residential high-rise where all calls from upper floors are down calls?

[@elevcraft4-elevators808]

Do it for modern elevators

[@Lift.Tracker]

They work very similarly. Although all there is to see is some flashing LEDs on a computer board.

[@tkeforever4809]

Why are the CDL’s (Car Direction Lantern) colors reversed. Should be GREEN for UP, RED for DOWN, just like the hall call buttons here!

[@mrmattandmrchay]

I've seen both and there isn't a definite rule. Green for go - green to enter the building (up), or green to exit the building (down) - who knows! But in this video, RED to portray the problem, GREEN to underline the way I want to go :)

[@monad_tcp]

its funny, with 5 hundreds of relays you can create a computer, but it would be kinda slow. that was so simple with pure relay logic

[@mrmattandmrchay]

there are videos on youtube that show a pure relay controlled computer! I don't think it's going to be able to host Fortnite though, probably used just for calculation.

[@monad_tcp]

@@mrmattandmrchay yep, how do you think I landed here. (to be fair, I'm curious about hidden infrastructure, I went to the channel 13 television tower in my city to see how the transmitter worked) keep up the good work !

[@Ham549]

Up should be green and down red

[@mrmattandmrchay]

I've seen both and there isn't a definite rule. Green for go - green to enter the building (up), or green to exit the building (down) - who knows! But in this video, RED to portray the problem, GREEN to underline the way I want to go :)

[@QuarioQuario54321]

Imagine what it would need to do for 8 elevators. That would seemingly require a computer.

[@RichPAFC1987]

Not difficult. You can have 3 or 4 lifts, with the system matt described, but TT relays wired in series between each one for up and down calls respectively. For large banks in a group, you would have a dispatcher cabinet that takes care of all hall call demands and picks a lift based on where it is and what direction its going.

[@andrewzapar2585]

That’s why destination dispatch exists

[@QuarioQuario54321]

@@andrewzapar2585 but that was only invented in the 1990s

[@MrBlageur]

Could you run a lift on an arduino mega 😂

[@BigKitty1011]

If you really wanted to, yes. But there is not a really good reason to so...

[@williamhuang8309]

The breakdown was very dramatic.

[@Lift.Tracker]

Eh, that’s probably what it would sound like if it’s an old lift.

[@perhaps3990]

2nd lol

[@MiamiMillionaire]

👍