zipped ladder.

[dmodiano]

I have attached a copy of a ladder diagram which is supposed to control the opening, closing, and stopping of a garage door. It's suppose to stop when the button opposite the direction the door is moving is pressed, without burning out the motor windings. Everything works, but the motor windings burn out. I think the problem I'm having is in understanding the use of the OSR instruction. An explanation would be greatly appreciated.
[attachment]

 

[Tom Jenkins]

I haven't looked at the program, but why are you convinced that there isn't a non-programming cause for the problem. Lots of things cause motor windings to burn out, whether they are controlled by a PLC or not. Is the voltage at the motor within the rating (including during starting and stopping, which causes voltage dips)? Are the motor leads sized properly and terminated properly? What is the ambient temperature? Is the motor rated for the full load of the door? Is the motor thermally rated to handle frequent starting and stopping? Is there a time delay or other means to stop the motor before you reverse it? Do you need a high starting torque motor?

 

[gbradley]

Yeah that One shot doesn't look right.
I think that it should be written to a bit like B3:0/1 not to an Output.
Also I think that the one shot should be after the trigger, and I'm not sure if you can branch it like that?
Good luck!

 

[gbradley]

This PDF file may help you.
Look for One shot rising.
Micrologix 1000

 

[ganutenator]

Amongst other things..... Your OSR will never work. This is because there are no conditional statements to the left of the OSR. One way to picture how the OSR works is the following. It passes power to the right, for one scan as soon as it gets power to the left of it. This cycle repeats every time power to the left of the OSR goes away and comes back.

It may be easier if you get rid of the latch instructions, and try and make it look something like the simple start circuit below.

 

        Start                Mtr Run  Mtr Run

        DOWN          Stop   DOWN     UP

--------| |-----------|\|----|\|-------( )

|               |

|      Mtr Run  |

|      UP       |

|-------| |-----|



       Start                 Mtr Run     Mtr Run

       UP             Stop   UP          DOWN

--------| |-----------|\|----|\|----------( )

|               |

|      Mtr Run  |

|      DOWN     |

|-------| |-----|