Help with limit switches

Discussion in 'General Electronics Chat' started by Mtmooradian, Jul 19, 2019.

  1. Mtmooradian

    Thread Starter New Member

    Jul 19, 2019
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    Looking to add an upper and lower limit switch to this control box.
    System runs a cogged belt up and down a track.
    I have a 3p motor control by a vfd
    Wireless controls(momentary) into the x terminals on the vfd(3wire control)

    I need to add two limit switches but they need to sequence. After tripping the limit, it decelerates and then passes back past the switch.
    I’m thinking of using latching relays in between the wireless and the vfd
     
  2. Mtmooradian

    Thread Starter New Member

    Jul 19, 2019
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    Hello, this thing on?
     
  3. KeithWalker

    Member

    Jul 10, 2017
    310
    93
    Can you show us a wiring diagram of your system? It would help us to understand what you have and how to modify it.
     
  4. Mtmooradian

    Thread Starter New Member

    Jul 19, 2019
    3
    0
    242DE0BE-BBB0-4EA4-B05C-619658DC452F.png 242DE0BE-BBB0-4EA4-B05C-619658DC452F.png 3C9D34C1-5E8E-4163-A177-D31789B7117F.png
     
  5. LesJones

    Well-Known Member

    Jan 8, 2017
    2,196
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    From what I can read of your very poor pictures it looks like you have a Siemens Logo 24RCE controlling the VFD. Is it not possible to reprogram the Logo 24RCE to do what you want. Is the VFD already programmed to ramp up on start and ramp down on stop ?

    Les.
     
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
    18,408
    5,653
    Can you post it in black and white? also the Logo outputs are not shown, usually any changes are easiest in the Logo, as Les mentioned.
    Do you have the logo logic program?
    Max.
     
  7. MisterBill2

    Distinguished Member

    Jan 23, 2018
    3,450
    679
    Some drive packages include limit switch inputs to do just exactly what you describe, while others do not support that function. You will need to consult the instructions for that drive to see if it can even work that way. I see that one post claims that function is not available with the drive that you have. In that case you may be out of luck. BUT you need to read and understand the manual for the drive.
     
    shteii01 likes this.
  8. shteii01

    AAC Fanatic!

    Feb 19, 2010
    4,667
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    Yeah, same as above. Some VFDs have a bunch of inputs that you can use. So. Crank open the VFD manual and start reading.
     
  9. MaxHeadRoom

    Expert

    Jul 18, 2013
    18,408
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    That Lenze version appears fairly limited as to control inputs, not that many options.
    Max.
     
  10. MisterBill2

    Distinguished Member

    Jan 23, 2018
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    I do not even see much of a speed control input, so it is not likely that ramping the speed down at some point is even possible. That is one reason that I have avoided the Siemens brand of equipment. If there is a directional control line and an analog speed control input then you could have either a simple RC ramp circuit handle the slowing at the end of a move or use a PLC with an analog output to generate the changing speed command. Once again, first study the manual to see what control functions are available.
     
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