"Simple" 3 Floor Elevator "Relay" Diagram

Discussion in 'The Projects Forum' started by NT01221, Oct 10, 2012.

  1. NT01221

    NT01221 Thread Starter New Member

    Joined:
    Oct 10, 2012
    Messages:
    5
    I am looking to build a 3 floor working model elevator using relays and limit switches. Not worried about doors opening and closing or variable speed, just a simple 3 floor up/down operation. A 2 floor diagram is quite easy, however adding a 3rd floor makes it that much more challenging using relays. Does anyone have a simple relay diagram they could share? I'd like to have an "up" call button on the 1st floor, an "up" and "down" call button on the 2nd floor, and a "down" call button on the 3rd floor. There would be an external panel of three buttons to represent the panel inside the elevator car for floors 1, 2 & 3. Put your thinking caps on, and please.... keep it simple!!
  2. MrCarlos

    MrCarlos Member

    Joined:
    Jan 2, 2010
    Messages:
    217
    Location:
    México
    Hello NT01221

    You can start by analyzing the circuit in the attached image.
    then:
    Could change the switches shown in the image attached by magnetic sensors that activate the relays.

    After:
    Increase call buttons on the other floors

    I hope this information will help you make your project

    regards
    at your service

    Attached Files:

  3. NT01221

    NT01221 Thread Starter New Member

    Joined:
    Oct 10, 2012
    Messages:
    5
    Thanks for your reply. I was hoping to get an actual relay diagram if someone could help me with that?
  4. KJ6EAD

    KJ6EAD Well-Known Member

    Joined:
    Apr 30, 2011
    Messages:
    1,104
    Location:
    Earth
    This seems like a PLC programming assignment for school.
  5. NT01221

    NT01221 Thread Starter New Member

    Joined:
    Oct 10, 2012
    Messages:
    5
    A good friend has an Autistic child who is fascinated with elevators. I wanted to build a working model for him, however I never worked with PLCs, so I wanted to keep with the technology I know. Would love a relay diagram if someone could help!
  6. JDT

    JDT Well-Known Member

    Joined:
    Feb 12, 2009
    Messages:
    577
    Location:
    UK
    Not simple - but interesting! I'm sure it can be done with relays - they must have done it that way back in the day. You will need latching relays to be able to "remember" things. Complicated! Get it wrong, you will have to re-wire.

    I would start this project by first: Consider what input and output devices you need. Example: at each floor you need a position switch to tell that the lift is there. A call button at each floor. An acknowledgement light at each floor to signal that the lift is coming. Motor forward (going up). Motor reverse (going down). I make that 6 inputs, 5 outputs. Might be more!

    Then the important bit. Draw a "state diagram". Each state is a box. Each state has a fixed output condition which is shown inside the box.

    How many states? 3 for the lift stationary at each floor. Probably another 6 for the lift travelling between floors - up and down. Draw arrows showing how the system moves between states. Note that, unlike the lift, the "states" move instantly.

    Work out which inputs have to switch to cause the state to change to the next state. Mark these on the arrows. For example, when the lift is stationary at the middle floor (at-2 state), it could either go up (going-up-to-3 state) or go down (going-down-to-1 state). What inputs have to change for this to happen? Not all inputs have to be acted on in every state. Example: if it's at floor 1 then the call button at that floor has no effect.

    Once you have got this right - and it might take some time! Then you can plan your control system. This is called a "systematic" method. I would draw your diagram on the computer in Visio or LibreOffice Draw so that you can change things until it's right.

    The beauty of a PLC over relays is that these states can be created in a "state machine" (Google that!). Directly simulating your diagram. Could also be done with CMOS logic or a micro-controller.
    Last edited: Oct 11, 2012
  7. williamj

    williamj Active Member

    Joined:
    Sep 3, 2009
    Messages:
    175
    NTO1221,

    Search this site for elevator and/or dumb waiter, there are several here already made out.

    williamj
  8. NT01221

    NT01221 Thread Starter New Member

    Joined:
    Oct 10, 2012
    Messages:
    5
    Well I guess by adding that third floor, things get complicated very quickly! I think I may go with just 2 floors and add a few extras like opening and closing doors, lights and a bell maybe. I never worked with a PLC before, but it sure sounds like the way to go. Looks like there are allot of used PLCs on EBay at great prices. Can anyone recommend a good type for me to look for as something to play around with? Maybe an Allen Bradley SLC100 or an Omron Sysmac Mini? Keep in mind, I need something simple to program. I assume you use some kind of ladder diagram software on a PCM and then load it into the PLC???
  9. JDT

    JDT Well-Known Member

    Joined:
    Feb 12, 2009
    Messages:
    577
    Location:
    UK
    Yes, plenty of PLCs on Ebay. The problem is programming. Make sure you can get the programming software before you buy. Some PLC not only need expensive software but also need a programming device or dongle to connect the PC to the PLC.

    Some more enlightened PLC manufacturers give away their programming software free, only charging for the actual PLC device (Omron and Matsushita - if I remember correctly).

    Another way to do this is to use a PC as your control system. using Serial to I/O or USB to I/O modules. This is known as a "soft PLC".

    Have a look at: http://www.audon.co.uk/cubloc_cpu/cb220.html
  10. NT01221

    NT01221 Thread Starter New Member

    Joined:
    Oct 10, 2012
    Messages:
    5
    Thanks again! I had a look at the Cubloc and have one ordered along with the training board so I can play around with it!
  11. gerty

    gerty Well-Known Member

    Joined:
    Aug 30, 2007
    Messages:
    930
    Location:
    Tennessee GMT -5
    Here's one we bought for school, you can choose how many inputs and outputs you'll need.
    You can download the software for free, write your program, try it on the free simulator, then buy the apprpriate Super Relay.
    http://www.classicautomation.com/micro-PLC.aspx
  12. Benyamin

    Benyamin New Member

    Joined:
    Jan 26, 2014
    Messages:
    1
Similar Threads
Forum Title Date
The Projects Forum Create a simple High pass filter to sense AC signal Sep 3, 2014
The Projects Forum Voltage Reg Simple Questions Aug 15, 2014
The Projects Forum Simple - Close a Circuit Aug 12, 2014
The Projects Forum simple solar panel project Jul 30, 2014
The Projects Forum Simple project powering a buzzer from a alarm clock Jul 24, 2014

Share This Page