motor on and off with single push button

saurabh_bmit · Aug 5, 2005

I'm a beginner in PLC education, struck with a problem. Anyone can please help. The problem is:

I have a single push button. When I press & release it first, motor should start and remain On.
When I press & release it again, the motor should turn off and remain off. And the same sequence to be accomplished every time I press & release the Button.

Please help me in developing a ladder diagram for this. Thanking you all in anticipation.

Cheers,

Saurabh

metaller · Aug 5, 2005

What kind of PLC do you programme?

Eric Nelson · Aug 5, 2005

Google knows good stuff!...

Hey, whadda know?!?! The 6^th link of a Google search for PLC Flip Flop is THIS page at Ron's site...

-Eric

jwall · Aug 5, 2005

Before you get to completing that, I would first try to understand what an e-stop is, and how you would use it.

In order to first get your motor to stay on. Begin with a memory bit. Have the memory bit on a normally open contact drive the motor ouput in an output coil

Turn the memory bit on with input button down and rising edge, to set the memory bit

Resest the memory bit if it is on, the button is down, and another rising edge, or off and falling edge.

This should probably be the easiest thing you will ever do in plcs

CaseyK · Aug 5, 2005

jwall said:
Before you get to completing that, I would first try to understand what an e-stop is, and how you would use it.

In an industrial application, you are so right.

In a school setting, sometimes understading the first three rungs of logic is overwhelming.

So, I would recommend getting the motor to start and stop, then work in the e-stop.

If our student doesn't understand e-stop, or emergency stop, do a search for either, and a lot of threads will pop up.

regards.....casey

BobB · Aug 7, 2005

Here is a link to an Omron toggle. It is really easy.

http://forum.mrplc.com/index.php?act=Downloads&CODE=02&id=160

Peter Nachtwey · Aug 7, 2005

Why is it that every student thinks they are the first to be assigned this problem?

Amr Hassan · Aug 7, 2005

it depends on

use this small code

a i0.0
fp m0.0
=m0.1

a m0.0
an q0.0
s q0.0
r m0.0

a m0.0
a q0.0
r q0.0

take care for this (r m0.0) other wise this will nort work

sidhu · Aug 7, 2005

Assume your pushbutton is digital input1. connect your input1 to a counter with counter value as constant 2. connect output of counter to comparator to check whether input is 1 or 2. if 1 then put on a digital output1 for starting a motor else put off digital output1. Also counter should get a reset. I hope this will solve your problem.

CaseyK · Aug 7, 2005

Peter Nachtwey said:
Why is it that every student thinks they are the first to be assigned this problem?

You mean they're not?

Maybe the "POST" button is easier to find then the search button.

regards.....casey

BTW I notice that he has only posted the one time...

Lancie1 · Aug 7, 2005

saurabh_bmit,

What everyone is saying is that this exact problem is a typical one and has been discussed about 283 times here at this site. Go to the top of the screen, click "Search" enter "toggle" as a keyword, press search, and you will see at least 283 different posts with solutions for different models of PLCs.

Johnny T · Aug 8, 2005

I think the most eloquent solution to this problem I ever saw was posted by S7Guy about 4 months ago. It was using S7 and involved the Xor function.

I think it was only three lines long...

We should run a book of dates on when and where the next one of these questions will appear... I'm going for August 14th around four o'clock...

BobB · Aug 8, 2005

Have a look at the Omron one posted above. 1 input (rising edge) a keep (latching) relay and one contact in the reset line. That has got to be the easiest one I have ever seen.

Terry Woods · Aug 8, 2005

Johnny T,

Just to let you know...
I posted an S7 program for this problem. It consisted of only 1-Rung.

Johnny T · Aug 8, 2005

Terry Woods said:
Johnny T,

Just to let you know...
I posted an S7 program for this problem. It consisted of only 1-Rung.

Now that is impressive...

)

motor on and off with single push button

saurabh_bmit

Member

metaller

Member

Eric Nelson

Lifetime Supporting Member + Moderator

jwall

Member

CaseyK

Member

BobB

Lifetime Supporting Member

Peter Nachtwey

Member

Amr Hassan

Member

sidhu

Member

CaseyK

Member

Lancie1

Lifetime Supporting Member

Johnny T

Member

BobB

Lifetime Supporting Member

Terry Woods

Member

Johnny T

Member

Similar Topics