Thank you so much for going to the effort of providing such a comprehensive look at how an elevator's circuitry and logic works. This is so fascinating to me, even though I am way too right-brained to do any kind of logic programming for a living.
This is most outstanding video which describe PLC inputs and outputs of an elevator with 2 speeds! Man, for those who understand, this is a colosal work! It is better than learning an entire book about PLC's. MrMattandMrChay you are the man!!
Excellent video, mate. What a find this elevator motoring... There is lot of things installed of elevator controlled units... It's so amazing of this elevator engineering as you visit! ^_^
Watching your videos inspired me to take a look in the LMR last time the engineer came for monthly maintenance. Looked like this, maybe a bit older - but not relays so must've been renovated since the building went up in 1973. I'm trying to persuade the building manager to install a VFD to replace the contactor - horrible shock each time it switches from full to half speed and half speed to stop. Real 'crash levelling'! Thanks for all your work. P.S. my 8 year old loved the spooky building and distant bangs when you hid in that old hotel :-)
Grea Video, very interesting to see how the actual I-O of the PLC had been arranged and how it reacts. I wouldnt imagine timers as back up in case of a PLC fail. Overrun switches wont cut power DIRECTLY, I mean, just tripping something and overriding the PLC ?. PLC, good stuff for lifts and many other things but I would prefeer a "proper" lift controller like the electronic ones in the 80s. I mean, controllers made to deal with lifts ... they looked more interesting
Actually, one of the timers is used to delay the brake coming on for half second - in the 60s the motor would run at 2 speeds. When the lift stopped, the brake came on with the motor still running as slow speed and you'd get a small SCREECH to a stop. Now, with the VFD (Variable Freq Drive) the motor's speed is controlled precisely, making much smoother transitions. So when the VFD receives the STOP command, it slows the motor down to a halt slowly. This in itself takes a very short time, so the timer delays the brake for half a second, so the motor is stationary when the brake is applied. The overrun switches would be part of the safety circuit. When these are triggered, the MC (Main Contactor) would drop out which removes power to the motor immediately, without the PLC getting involved. One of the PLCs Inputs would drop out at the same time, so the PLC would know something is wrong. If the lift was at a floor zone, I bet it's programmed to open the doors under this condition. Else, you are probably stuck, until the safety circuit is made again (fire brigade rescue!).
Safety circuit wiring is always BEFORE the Normal/Test switch, therefore that input to the PLC would go 0 if the safety line is opened at any point. Safety circuit does NOT include the Landing lock and car gate contacts which are wired seperately.
(sorry for late response) Yep, If I were to show you what I had to do (especially the "light bulb panel" overlay) to create this and synchronise it then you'd be amazed! But don't forget that I only do this in my spare time, which is why it spanned over 2 months :)
Great Video Mr. Matt! Your efforts are appreciated! My question- based on this logic layout, I don't see how the lift can determine the desired direction of travel from a second floor request. Does the second floor have separate up/down buttons? I only see one input
Please elaborate as I'm not sure i'm understanding the question here. The PLC knows where the lift is, so it's programmed "if call above car, then go up" and there is an input from each call button. I'm sure you already know this :) but please explain your question again? Thanks.
Oops, let me rephrase that to be a bit more clear. By "second floor" I actually mean "middle floor," my mistake! So- if the elevator has a passenger going from G to 2, and there's someone at 1 who wants to go down, the elevator will stop at 1 on it's way up to 2. Because with this logic, I don't see how the elevator can "know" what direction of travel the person on the middle floor wants to go- there's only one input for the middle floor!
This video shows an APB SYSTEM (AUTOMATIC PUSH BUTTON) it is Non collective and is the most basic of all lift call systems. The lift car will stop at all landing calls as they are registered, a collective system is more advanced and would have 2 push buttons on intermediate floors and the calls would be answered in sequence depending on the direction of travel.
Fascinating stuff. I love learning about how things work. What is that black box near the contactors with the yellow bit that keeps popping out? I would love for you to come and film some of the lifts in my area. Some of them make me curious.
Thanks for the comment. That black box is a contactor. There are lots of them (next to the black one) and they all the same. But the one you are referring to has been replace from the grey type to the black one (probably it went faulty), but they all do the same thing. The black one has that visible yellow bar the goes in and out. The grey ones have something similar (a little slider left-right), but you can't easily see it.Anyway, these are CONTACTORS. So, to make a motor move it must be connected to voltage. But motors takes a lot more current (amps) to make it move. So to switch voltage to motors, you have to run it through a contactor, as as a contactor is designed for higher voltages/currents. A contactor connects and disconnects the voltage to each wire that goes to the motor. So when the contactor is off, the motor is completely disconnected from voltage.The contactor you are looking at (the black one) connects voltage to make the DOORS OPEN. The one on the right of it is the DOOR CLOSE. The contactors on the left are for the main motor UP/DOWN.
In between this, the company was called "Kone Marryat Scott". Lifts in Princess Square in Bracknell were this in the early 80s... th-cam.com/video/whpH1cho9U8/w-d-xo.html (described at about 1:50)
Hi, interesting you should mention this, because I've done a very similar video here: th-cam.com/video/WadV7hyxxxQ/w-d-xo.html This one actually took longer to edit than this one.
How are these 80's PLC's programmed? Nowerdays a lot of controllers have a RS232 serial interface and the engineer can simply upload the configuarion to it. How do they compare with say modern microcontrollers like atmel or pic? I wonder what kind of memory strorage they use. Is it a ram chip with a battery or is it an eprom or perhaps a floppy drive? Some consumer electronics used ram chips to store user settings and where powered by a super cap or a watch battery when the power was off, nowerdays everyting uses flash memory instead. I suppose the Led matrix floor indicator is a seperate system on it's own with it's own controller inside the to decode the outputs from the PLC.
You are right with everything! A lot of the old technology PLCs require you to write the computer program then "blow" it on to an EPROM. This EPROM chip is then plugged onto the main board. The one in this video, I would image is similar to what you are saying. You probably log-on to it with a serial interface and upload the program, it reboots and runs it. If you were to buy a new PLC (I have one actually) then on mine there are a couple of options - you can either write the program using the in-built LCD screen, or connect to it via a serial lead. It comes with software, so you can build your computer program graphically (using AND, OR symbols). Back in the 80s/90s you would need to know a little about coding to write a program to control a lift via a PLC. You are exactly right with the matrix display. There is either a controller in the cabinet that sends 485/232 data to the matrix displays (these are probably addressed) or the matrix display has some intelligence and runs off inputs to show the relevant floors or arrows. I have lots of experience of writing coding on 80s/90s platforms, I learnt how to program BASIC language when I was about 10 years old on a ZX Spectrum! I do like coding, I do a little visual basic but I don't really know modern-day languages that well at all, and no time to learn them. What I don't understand it, in QBASIC if there is a bug, then the program stops and you can interrogate it (i.e. find out where the program terminated, probe the variables, get it to run from where the fault is, until it goes again). Modern day languages compile the code into an EXE. When that has a fault, I don't understand what tools you have to be able to fault find, as you could do with QBASIC.
+mrmattandmrchay Well, my dad is an electronics guy, who tinkers with atmel micro controllers. He made a few projects for me (mostly gaming related), and he started hobby programming in the 80's on a BBC model B. I'm building / structural engineer but I have cought the programming virus early on, I did a bit of game programming in the 2000's with div gamesstudio which is a pascal/c hybrid. My dad and I often watch the EEVBLOG too. Lifts for me basically bridge the building design world and the electronics world. Did you know that old catridge games often used battery backed up memory to incoperate a safe feature? They almost always had mask roms in them which are quite durable unlike eproms.
I learnt programming on 80's computers, Zx spectrum included and avoided learning programming on PC's for a long time. The hardware on pc's 10 or 15 years old is infinitely better than 80's home computers. Languages like VB.net or C, java, Android. Have a wealth of libraries/functions built in to help you do everything imaginable using the available hardware. When debugging a VB program you've written you can still pause and view errors debug etc whilst it's running, When you perfect your program you save a release version of the EXE. I'm still new to VB.net, but it's very powerful and quick to build professional applications using it. Now I'm off to design and build my own series of lift controllers based on your video :-)
For the outputs "open door" and "close door", I'm thinking it's referring to the doors on the lift. But what about the doors on the actual floors themselves? I don't see any that go to those...
Thanks for your Question (sorry for late response). The door switches go to the GATE CONTACTS input. These are all connected in a line. If ANY of the doors are unlocked, then this GATE CONTACT input drops out - this will stop the lift wherever it is, and it won't travel without the input going activate. So, essentially, the PLC doesn't care "which" floor's door is open and it doesn't matter. If a door is unlocked/open on any floor then the lift won't move. Hope that answers your question.
You are wrong actually! Mostly, I set as many cameras up as possible and film the run with all cameras recording at the same time. If I can't do this, then I try to film exactly the same sequence twice - the first time I have the camera with me, the second time the camera is in the motor room, then I have to do a bit of editing to make the sequences match exactly. For "this" video, I had all cameras running at the same time. 1) Sony W350 was filming the controller, 2) Innovv C2 (fish eye) filming the motor, 3) My phone with me in the lift.
there is this really old lift at my local city market and when ever you go down from two or three to one it takes so long to level and going up to three it's old
Their are a couple of possibilities for this, you have the counterweight effect where the machine is hoisting a heavier load than the lift car or the slowing plate for the 1st floor down needs adjustment.
First I was about to give it a thumbs down as you blamed the cat(flap) for the sinking of the submarine. Just kidding, great video (plus nice sense of humor) and I knwo you spent a whole lot of time editing it. Your explanations are great, even though that stuff is not new to me - I don't work on lifts, but industrial controls. ;-) Funny you do that on a lift with PLC even though you don't like them?! Many thx from Germany!
I have watched through all of your videos (okay, just the ones about lifts, as I don't find watching sirens too thrilling) and I really like your style of commenting and the humor you sometimes add. :-) I have only been to a lift motor room once (the house we lived in when i was a kid (built in 1963) had a lift in it and I was allowed in the motor room once in the early 1990s. It was built by an independent German manufacturer (now defunct) too bad I don't remember any details. But I am quite sure it still had the original relays as the building owner did not spend a lot of money on the building for modernization and renovation. Okay, I have been to a couple more lift motor rooms, but that were paternoster lifts. Interesting from a mechanical point of view, but controls are limited to a simple on/off switch. ;-)
The PLC is not that busy, even older CPU's can run a many millions of operations a second those inputs change very slowly. The variable frequency drive has a harder job generating those motor waveforms, calculating motor currents/voltages etc in real time.
Were you given permission to use the lift for the video? It seems like a lot of stuff to do while attempting to hide from the building's owner, not to mention the sound of the lift running.
It's a virtually unoccupied building. Offices to let, but due to the old design (no double glazing, and more 1960s design issues) no one is renting it out. I was in there on my own to maintain one of the systems. FYI, I'm going to delete this comment (you should receive it in an email I hope) just in case, else they will know exactly who it was!
Thank you so much for going to the effort of providing such a comprehensive look at how an elevator's circuitry and logic works. This is so fascinating to me, even though I am way too right-brained to do any kind of logic programming for a living.
+David Irwin (passacaglia28) thanks for your comment. I'd love to build a lift model and program it up though. .. maybe when i retire! !
This is most outstanding video which describe PLC inputs and outputs of an elevator with 2 speeds!
Man, for those who understand, this is a colosal work! It is better than learning an entire book about PLC's.
MrMattandMrChay you are the man!!
Bardhyl Maliqi This has a VFD and doesn’t have 2 speeds
Awesome work! Great to learn and get to know how these things work. Thank you very much!
So much detail in this lift, thanks. your time and effort has paid off :)
You covered every aspect of the elevator GREATT!
omg mrmatt! thakyou so much for this amazing production!
Thanks :) Check out this one also: th-cam.com/video/WadV7hyxxxQ/w-d-xo.html This one took longer to edit, same multicamera angles, PLC, and more.
Excellent video, mate. What a find this elevator motoring... There is lot of things installed of elevator controlled units... It's so amazing of this elevator engineering as you visit! ^_^
Truly awesome unique video which could be used out of the box in a training course. Brilliant!
Cool glad you liked it :)
Great video, Can not wait for the other 3 videos...
Thanks :) I have 3 others 75% done.
Watching your videos inspired me to take a look in the LMR last time the engineer came for monthly maintenance. Looked like this, maybe a bit older - but not relays so must've been renovated since the building went up in 1973. I'm trying to persuade the building manager to install a VFD to replace the contactor - horrible shock each time it switches from full to half speed and half speed to stop. Real 'crash levelling'! Thanks for all your work. P.S. my 8 year old loved the spooky building and distant bangs when you hid in that old hotel :-)
Thanks you for your videos. I love your videos. Please continue your videos !
cool, thanks for the comment
Grea Video, very interesting to see how the actual I-O of the PLC had been arranged and how it reacts. I wouldnt imagine timers as back up in case of a PLC fail. Overrun switches wont cut power DIRECTLY, I mean, just tripping something and overriding the PLC ?. PLC, good stuff for lifts and many other things but I would prefeer a "proper" lift controller like the electronic ones in the 80s. I mean, controllers made to deal with lifts ... they looked more interesting
Actually, one of the timers is used to delay the brake coming on for half second - in the 60s the motor would run at 2 speeds. When the lift stopped, the brake came on with the motor still running as slow speed and you'd get a small SCREECH to a stop. Now, with the VFD (Variable Freq Drive) the motor's speed is controlled precisely, making much smoother transitions. So when the VFD receives the STOP command, it slows the motor down to a halt slowly. This in itself takes a very short time, so the timer delays the brake for half a second, so the motor is stationary when the brake is applied.
The overrun switches would be part of the safety circuit. When these are triggered, the MC (Main Contactor) would drop out which removes power to the motor immediately, without the PLC getting involved. One of the PLCs Inputs would drop out at the same time, so the PLC would know something is wrong. If the lift was at a floor zone, I bet it's programmed to open the doors under this condition. Else, you are probably stuck, until the safety circuit is made again (fire brigade rescue!).
Safety circuit wiring is always BEFORE the Normal/Test switch, therefore that input to the PLC would go 0 if the safety line is opened at any point. Safety circuit does NOT include the Landing lock and car gate contacts which are wired seperately.
The logic works in Octal.
So, that Mitsubishi uses a Octal operating system?
Mitsubishi PLC I mean
hey man, its brandon again, nice video, and whoa!!!! 2 months of editing!?!?
(sorry for late response) Yep, If I were to show you what I had to do (especially the "light bulb panel" overlay) to create this and synchronise it then you'd be amazed! But don't forget that I only do this in my spare time, which is why it spanned over 2 months :)
Nice
Do you still have any fears of elevators? It can be anything. You can respond to my question if you'd like I don't mind, it might be personal
Great Video Mr. Matt! Your efforts are appreciated!
My question- based on this logic layout, I don't see how the lift can determine the desired direction of travel from a second floor request. Does the second floor have separate up/down buttons? I only see one input
Please elaborate as I'm not sure i'm understanding the question here. The PLC knows where the lift is, so it's programmed "if call above car, then go up" and there is an input from each call button. I'm sure you already know this :) but please explain your question again? Thanks.
Oops, let me rephrase that to be a bit more clear. By "second floor" I actually mean "middle floor," my mistake!
So- if the elevator has a passenger going from G to 2, and there's someone at 1 who wants to go down, the elevator will stop at 1 on it's way up to 2. Because with this logic, I don't see how the elevator can "know" what direction of travel the person on the middle floor wants to go- there's only one input for the middle floor!
This video shows an APB SYSTEM (AUTOMATIC PUSH BUTTON) it is Non collective and is the most basic of all lift call systems. The lift car will stop at all landing calls as they are registered, a collective system is more advanced and would have 2 push buttons on intermediate floors and the calls would be answered in sequence depending on the direction of travel.
Vakuum cleaner on the moon. Got me
Fascinating stuff. I love learning about how things work.
What is that black box near the contactors with the yellow bit that keeps popping out?
I would love for you to come and film some of the lifts in my area. Some of them make me curious.
Thanks for the comment. That black box is a contactor. There are lots of them (next to the black one) and they all the same. But the one you are referring to has been replace from the grey type to the black one (probably it went faulty), but they all do the same thing. The black one has that visible yellow bar the goes in and out. The grey ones have something similar (a little slider left-right), but you can't easily see it.Anyway, these are CONTACTORS. So, to make a motor move it must be connected to voltage. But motors takes a lot more current (amps) to make it move. So to switch voltage to motors, you have to run it through a contactor, as as a contactor is designed for higher voltages/currents. A contactor connects and disconnects the voltage to each wire that goes to the motor. So when the contactor is off, the motor is completely disconnected from voltage.The contactor you are looking at (the black one) connects voltage to make the DOORS OPEN. The one on the right of it is the DOOR CLOSE. The contactors on the left are for the main motor UP/DOWN.
Great work!!!
thanks :)
Nice work!
Awesome!
Marryat Scott became Kone just incase some people dont know
In between this, the company was called "Kone Marryat Scott". Lifts in Princess Square in Bracknell were this in the early 80s... th-cam.com/video/whpH1cho9U8/w-d-xo.html (described at about 1:50)
Which elevator did you take this shaft view at 4:09 ?
That PLC would have loads of outputs and inputs in a high-rise lift
Hi, interesting you should mention this, because I've done a very similar video here: th-cam.com/video/WadV7hyxxxQ/w-d-xo.html This one actually took longer to edit than this one.
Yes, both videos are awesome!
excellent video thank you are you a lift engineer?
He is!
How are these 80's PLC's programmed? Nowerdays a lot of controllers have a RS232 serial interface and the engineer can simply upload the configuarion to it. How do they compare with say modern microcontrollers like atmel or pic? I wonder what kind of memory strorage they use. Is it a ram chip with a battery or is it an eprom or perhaps a floppy drive? Some consumer electronics used ram chips to store user settings and where powered by a super cap or a watch battery when the power was off, nowerdays everyting uses flash memory instead. I suppose the Led matrix floor indicator is a seperate system on it's own with it's own controller inside the to decode the outputs from the PLC.
You are right with everything!
A lot of the old technology PLCs require you to write the computer program then "blow" it on to an EPROM. This EPROM chip is then plugged onto the main board. The one in this video, I would image is similar to what you are saying. You probably log-on to it with a serial interface and upload the program, it reboots and runs it. If you were to buy a new PLC (I have one actually) then on mine there are a couple of options - you can either write the program using the in-built LCD screen, or connect to it via a serial lead. It comes with software, so you can build your computer program graphically (using AND, OR symbols). Back in the 80s/90s you would need to know a little about coding to write a program to control a lift via a PLC.
You are exactly right with the matrix display. There is either a controller in the cabinet that sends 485/232 data to the matrix displays (these are probably addressed) or the matrix display has some intelligence and runs off inputs to show the relevant floors or arrows.
I have lots of experience of writing coding on 80s/90s platforms, I learnt how to program BASIC language when I was about 10 years old on a ZX Spectrum! I do like coding, I do a little visual basic but I don't really know modern-day languages that well at all, and no time to learn them. What I don't understand it, in QBASIC if there is a bug, then the program stops and you can interrogate it (i.e. find out where the program terminated, probe the variables, get it to run from where the fault is, until it goes again). Modern day languages compile the code into an EXE. When that has a fault, I don't understand what tools you have to be able to fault find, as you could do with QBASIC.
+mrmattandmrchay Well, my dad is an electronics guy, who tinkers with atmel micro controllers. He made a few projects for me (mostly gaming related), and he started hobby programming in the 80's on a BBC model B. I'm building / structural engineer but I have cought the programming virus early on, I did a bit of game programming in the 2000's with div gamesstudio which is a pascal/c hybrid. My dad and I often watch the EEVBLOG too. Lifts for me basically bridge the building design world and the electronics world. Did you know that old catridge games often used battery backed up memory to incoperate a safe feature? They almost always had mask roms in them which are quite durable unlike eproms.
I learnt programming on 80's computers, Zx spectrum included and avoided learning programming on PC's for a long time. The hardware on pc's 10 or 15 years old is infinitely better than 80's home computers. Languages like VB.net or C, java, Android. Have a wealth of libraries/functions built in to help you do everything imaginable using the available hardware. When debugging a VB program you've written you can still pause and view errors debug etc whilst it's running, When you perfect your program you save a release version of the EXE. I'm still new to VB.net, but it's very powerful and quick to build professional applications using it. Now I'm off to design and build my own series of lift controllers based on your video :-)
For the outputs "open door" and "close door", I'm thinking it's referring to the doors on the lift. But what about the doors on the actual floors themselves? I don't see any that go to those...
Thanks for your Question (sorry for late response). The door switches go to the GATE CONTACTS input. These are all connected in a line. If ANY of the doors are unlocked, then this GATE CONTACT input drops out - this will stop the lift wherever it is, and it won't travel without the input going activate. So, essentially, the PLC doesn't care "which" floor's door is open and it doesn't matter. If a door is unlocked/open on any floor then the lift won't move. Hope that answers your question.
Aha! So that's how you do these mult-cam videos! You have your kid inside the lift while you play in the control room, lol :-)
You are wrong actually! Mostly, I set as many cameras up as possible and film the run with all cameras recording at the same time. If I can't do this, then I try to film exactly the same sequence twice - the first time I have the camera with me, the second time the camera is in the motor room, then I have to do a bit of editing to make the sequences match exactly. For "this" video, I had all cameras running at the same time. 1) Sony W350 was filming the controller, 2) Innovv C2 (fish eye) filming the motor, 3) My phone with me in the lift.
mrmattandmrchay That's amazing you can do that and synchronize it all! :-)
there is this really old lift at my local city market and when ever you go down from two or three to one it takes so long to level and going up to three it's old
Their are a couple of possibilities for this, you have the counterweight effect where the machine is hoisting a heavier load than the lift car or the slowing plate for the 1st floor down needs adjustment.
1:00 Do I really have to read all of this?!
haha yeah Chay complaining about doing the voiceover!
First I was about to give it a thumbs down as you blamed the cat(flap) for the sinking of the submarine. Just kidding, great video (plus nice sense of humor) and I knwo you spent a whole lot of time editing it. Your explanations are great, even though that stuff is not new to me - I don't work on lifts, but industrial controls. ;-) Funny you do that on a lift with PLC even though you don't like them?! Many thx from Germany!
Thanks for your comment, that submarine sinking sequence took me about an hour haha (even though it lasts for about a second), glad you liked it!
I have watched through all of your videos (okay, just the ones about lifts, as I don't find watching sirens too thrilling) and I really like your style of commenting and the humor you sometimes add. :-)
I have only been to a lift motor room once (the house we lived in when i was a kid (built in 1963) had a lift in it and I was allowed in the motor room once in the early 1990s. It was built by an independent German manufacturer (now defunct) too bad I don't remember any details. But I am quite sure it still had the original relays as the building owner did not spend a lot of money on the building for modernization and renovation. Okay, I have been to a couple more lift motor rooms, but that were paternoster lifts. Interesting from a mechanical point of view, but controls are limited to a simple on/off switch. ;-)
It pre-doors!
a lift computer has a lot of work to do.
This is what makes lifts so interesting - behind the scenes, how it works, etc. Passengers don't get to see any of this (most probably don't care lol)
now i am more educated about lift operation.
The PLC is not that busy, even older CPU's can run a many millions of operations a second those inputs change very slowly. The variable frequency drive has a harder job generating those motor waveforms, calculating motor currents/voltages etc in real time.
Were you given permission to use the lift for the video? It seems like a lot of stuff to do while attempting to hide from the building's owner, not to mention the sound of the lift running.
It's a virtually unoccupied building. Offices to let, but due to the old design (no double glazing, and more 1960s design issues) no one is renting it out. I was in there on my own to maintain one of the systems. FYI, I'm going to delete this comment (you should receive it in an email I hope) just in case, else they will know exactly who it was!
+mrmattandmrchay Ah I see. Thanks for the reply and the amazing content. =D