College PLC project Help

Thread Starter

stotty111

Joined Oct 21, 2018
9
For a start I would use the normal start rung you have but with a internal bit register in place of the M3.
From the program description I assume there is no E-Stop, just a sequential stop?
Max.
hi are you available to discuss this thread , i have the same project for my college plc classroom report and have the same issue were i require the stop button to stop the motors in reverse order with 20 sec delay. I can start the motors up in the correct order with the specific timed delayed starts.


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This this thread was moved from Help with a Simple PLC ladder diagram.
 

Thread Starter

stotty111

Joined Oct 21, 2018
9
Hi there , looking for a little help creating a ladder programme for my college project .

I require to create a ladder programme for 3 motor / Conveyors. M1 , M2 , M3 we will call them .

The programme requires the start button to start the motors up in the order
M3 starts straight away , then 30 sec delay until M2 starts then a further 30 sec delay until motor 1 starts up.

once they are up and running the stop button then requires the motors to stop in reverse order .
M1 stops straight away , then after 30 secs M2 , then after a further 30 secs M1 stops.

note a operation/ warning light also has to be tied in for the first motor running until the last motor stops as part of safety feature along with the standard etop

any help would be great , I can upload the drawing if required to give a visual
 

Thread Starter

stotty111

Joined Oct 21, 2018
9
Yeah I have managed to get what i think is the sequence start which is M3 , M2 . M1 , i have used 2 timers starting at the same time , one with 30 sec delay and one with 60 sec delay .

ie. motor 3 instant then motor 2 + 30 secs motor 3 + 60secs from motor1 start

what am struggling with is to get them to stop in reverse order , with timed delay . keeping the control loop active to operate timers to have the motors stop M1 , M2 , M3

also just realized in need to include and system operational Light during the time any motors are running sa a visual saftey along with standard estop .

any help would be appreciated. if you like i can email you what i have so far.
 

Uilnaydar

Joined Jan 30, 2008
118
Since this is homework, you'll need to let us know what YOUR proposed solution is and how you got there. Also, there are a bunch of different ways to write ladder logic. You will need to let us know what your course is asking for. I could give you a solution in ABB's software but you may be required to use Rockwell or Siemens.

As with all things electronic.... more information is more better than less information.
 

MaxHeadRoom

Joined Jul 18, 2013
20,668
Some initial thoughts.
I would set up a couple of internal status relays that are operated by a MOM Start P.B. and Stop P.B. these would latch in two internal relays, B3:'s in a A-B PLC .
These would register the status mode of the conveyor.
Use two 20sec timers for start and two 30 sec timers for the stop process, conveyor M2 would have both in its rung.
One task mentioned is to explain safety features, so I would make the first rung a E-Stop rung that used a operator E-Stop P.B. input, it could also have an external inputs if needed as in a External system E_Stop.
This would be a external output to register by way of any means needed to advise that a local E-Stop had occurred and maybe use the output to light a Red indicator.
This would also stop all conveyor motion outputs immediately instead of a sequence stop.
This would have to be cleared before a Start was permitted.
Incidentally, most PLC's have an instruction such as a MCR or Master Control Relay, this is a special internal relay known as a MCR and allows it to be used to disable all outputs between it and a MCR end rung, this acts just like a hard wired E-Stop where power is removed from a set of relays/contactors etc.
Something to mull over anyway.
Max.
 

Thread Starter

stotty111

Joined Oct 21, 2018
9
Some initial thoughts.
I would set up a couple of internal status relays that are operated by a MOM Start P.B. and Stop P.B. these would latch in two internal relays, B3:'s in a A-B PLC .
These would register the status mode of the conveyor.
Use two 20sec timers for start and two 30 sec timers for the stop process, conveyor M2 would have both in its rung.
One task mentioned is to explain safety features, so I would make the first rung a E-Stop rung that used a operator E-Stop P.B. input, it could also have an external inputs if needed as in a External system E_Stop.
This would be a external output to register by way of any means needed to advise that a local E-Stop had occurred and maybe use the output to light a Red indicator.
This would also stop all conveyor motion outputs immediately instead of a sequence stop.
This would have to be cleared before a Start was permitted.
Incidentally, most PLC's have an instruction such as a MCR or Master Control Relay, this is a special internal relay known as a MCR and allows it to be used to disable all outputs between it and a MCR end rung, this acts just like a hard wired E-Stop where power is removed from a set of relays/contactors etc.
Something to mull over anyway.
Max.

did you have a look at my ladder attempt , is it a million miles away .
 

MaxHeadRoom

Joined Jul 18, 2013
20,668
The NOT T4 in the M1 string can be NOT M0.
Where is the 60sec time delay for M3 off? It will stop as soon as a Stop is initiated.
Max.
 

Thread Starter

stotty111

Joined Oct 21, 2018
9
The NOT T4 in the M1 string can be NOT M0.
Where is the 60sec time delay for M3 off? It will stop as soon as a Stop is initiated.
Max.
could you ammend my drawing to suit , if you have 5 mins .

the stopping has to be in reverse order ,. the sytem has to starts M1 , M2 , M3 and stop M3 M2 M1
 
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