How would you solve this problem in ladder?

[tiria]

A motor will be controlled by two switches.The Go switch will start the motor and the Stop switch will stop it. If the Stop switch was used to stop the motor, the Go switch must be thrown twice to start the motor. When the motor is active a light should be turned on. The Stop switch will be wired as normally closed.

[Ron_S]

How would you solve it?

[tiria]

Honestly somebody asked me and I got confused writing the ladder.

[Ron_S]

A teacher perhaps?

Post where you are stuck and somebody will help

We won't do it for you

[Stuart_Wales]

haha 100% a college question right here.

[tiria]

Here is the code I've written so far.It does not work well enough though.The part on throwing the start switch twice if stop was used to stop the motor is the problem.

motor_with_counter_on _stop.gx3

[Ron_S]

Ah well, fair do's you have had a go.

It's a strange task to be set seing as the stop button is the only way to stop the motor (and you said 'if)

and then having to press start twice to make it go again but if that is what it is.............

Here's some of YOUR code slightly altered

There are some differences

1, why have I made the stop button N/O

2, why is MO now in series with the start button

3, What happens to the coil of MO when the stop is pressed

 

[tiria]

Thanks.

Yes the question needs some review as it seems not to be workable as it is.It is a college question as I tutor college kids when I'm free.I wanted to find a better way to tackle the question.

Regards.

 

[Transistor]

Just a hint:

Create a counter with a preset of '2' and increment the count with the start button.

Q1. How will you control when the output turns on?

Q2. What is the simplest way for the stop button to re-initialise everything.

Q3. Can you guarantee that STOP will override START?

Two lines of ladder should do the trick.

Note: it is best practice to wire the STOP button using a normally closed contact arrangement. That way, if a wire falls off or gets cut the circuit will stop.

[kraykov]

An example of a counter. It can be used for your task.

Edited February 16, 2018 by kraykov

[Ron_S]

Why have you done it?

To look clever¿

 

Most could do the simple task but the poster learns nothing.

 

I was doing in parts and asking why....... Sigh

 

 

 

 

[kraykov]

Sorry Ron_s! You are right about the damage from the ready solutions.

 

Edited February 16, 2018 by kraykov