Need help with for/rev. motor control logic

[MR.Electrician]

Hello everybody
Ok I can't get this . I want to know if I can use same input for either direction for./rev. And can use same input to denergize the output . For example
If I got no. PE to turn on Forward and NC prox to denergize and same thing for reverse.
Can some please tell me if something like this is possible.
Appreciate the help guys.

 

[iant]

There is only one way I can suggest we move forward on this.

we need to see what u are trying to do...
Can you download a program like SKETCHUP and draw you ladder dwg
then print it to a PDF format
Use an emulator or similar

Alternatively - write your program in Boolean.

But give us something to look at

 

[bce123]

can you tell us what your end goal ie: move from point a to b and back with some kind of prox to tell you how far you travel? try and explan your goal. Thanks, Steve

 

[iant]

http://www.plctalk.net/qanda/showthread.php?t=65454
This is a directly related second post

 

[bce123]

sounds like you need to latch a bit on for each and unlatch it when that ster is complete us these bits to lockout the other step what type of plc are you using?

 

[MR.Electrician]

Iant I will post a layout as soon as I get a chance.
To bce .. I am using micrologix 1000. And I tried latching but as soon as for. unlaches it latches rev. M really confused.
I will post my ladder diagram in next post .
Thanx for help.

 

[MR.Electrician]

Ok i got a snapshot of that window. Its because the computer we use to programe is strictly for programing and i dont have no way to get on internet from that. It will be very time consuming to get everything together. Hopefully this will help.

The first output i made a mistake on that its actually left motor.**

 

[bce123]

Mr Electrican, I don't see an not left motor in the logix for the motor Right rung and you don't have a not moter right in the logix for the motor left rung. I do not see why you need the fill P.B.s in the auto rungs did you put this in to get them to work for now? I would use a set and reset bit for each side and have the limit and prox that call for the motor to move to do the set and use the e-stop and the prox that that tells you that step is done to do the reset. then just use that bit to latch out the other side until the fill is complete. you could use what you have and just put the not motor as an and right after your e-stop and do away with your P.B.s in the auto rung and move your branch to latch in around the limit and the first prox. hope this helps, Steve

 

[MR.Electrician]

Thanx for reply Steve. I put those pb s in there to get to work in mean time. I am using rslogix 500 and I don't have set and reset. Correct me if I am wrong but I think they are same as latch and unlatch which I tried and it did not work.

 

[Lancie1]

Yes, Latch and Unlatch are the same functions as Set and Reset in other programming languages. Latch will hold a relay on until you Unlatch it, but knowing when to do each is the key to making it work.

 

[MR.Electrician]

Yes. Its a lil confusing since this is my first real world project. I don't know what m doing wrong. It keeps on unlatching one and matching other without going to next step.

 

[bernie_carlton]

The key to why you are failing in this project is that you are thinking about it incorrectly.

You are trying to analyze the action in terms of the motor movement. But the motor movement is only part of the operation. The filling of the bin is the other part.

So forget about moving the motor for a while.

You have three possible states:

1. The system is not trying to fill either bin.
2. The system is trying to fill the left bin.
3. The system is trying to fill the right bin.

This system will transfer from 1 <-> 2 or 1 <-> 3. State '1' is just not being in either state 2 or 3.

Now let's break down one of the 'fill' states. It is started by being in state '1', a bin being at the limit switch and the bin not being full.

Note that I have mention nothing yet about the position of the fill mechanism.

Now the 'fill' state is broken down into two sections.

1. The motor must move the fill mechanism so it is over the bin.

2. Once the mechanism is over the bin, the fill mechanism turns on to fill the bin.

As mentioned in the previous paragraph, the indication that the bin is full will terminate this state.

The nature of the scan will prevent both states 2 and 3 from being on at the same time but you can put in a NC of the other state if you wish.

I know you have not mentioned an output to the fill mechanism.

If you specify the actual Micrologix 1000 Input address for each of your identified inputs and the Output address for the motor movement we can begin to actually make progress.

 

[Lancie1]

Mr. Electrician,

Does these two rungs have the correct Inputs and Outputs that you have now?

 

[MR.Electrician]

Yes. That's the way I have it programmed bow and its running but have to push PB everytime.

 

[Lancie1]

Okay. It seems the Box Full Prox switches will keep it from starting automatically. Explain how those work, please. You said there are TWO prox switches that indicate Box Full, but are they wired to the SAME PLC input 4?