Turning Cw and CCW after a delay

Hi there

I am trying to write a simple ladder program for my PLC in order to run CW for one second then CCW for another one second and a delay of 3 second and then start all

Over again. I was able to come up with some codes. which I just attached my file:

The problem is as I am using a simple NO (Normally Open) push button in order to star the process, Every thing is fine as long as I hole the Button Down, but as I release it.

The system stops. I now I can solve the problem using a NC Push Button, But I want to be able to do it inside my PLC "SET" function or any other functions.

Any recommendation would be highly appreciated.



Regards

Jhonansaro

Search Flip Flop on this site. Using a flip flop you could use the same NO push button to start and stop the process.

CW and CCW after adelay

Hi There

Thanks for the reply, I am new to plc programming, please bare with me.

Attached are my codes in pdf, My PLC is Delta Model 14ss2

My codes do what I want them to do, but as soon as I release my finger form the NO start button, the program stops. (I tried the NC Push Button in X0, but again no success)

I know I can use on and off switch to solve the problem, But I like to know if I could do it using the NO Push Button*and modify my codes

In order to do the same job?

Regards

Jhonansaro

Welcome to the forum.
I am unable to open your file, so I will help where I can.

you only want to use 1 pushbutton to do the job.

1. press the pb one time ( this is count #1) to start the job.
2. run the system cw for 1 second.
3. run the system ccw for 1 second.
4. delay for 3 seconds.
5 goto step 2.
6. pressing the pb again (this is count #2 ) stops the job.

MY BIG question is what are you controlling?
if it's a motor, this is a big problem.
please explain what you are trying to power cw and ccw.

james

CW and CCW after adelay

Hi James Mcquade

Thanks for the reply.

Attached are two versions of my code, that basically they do what I want them to do, Except that as soon as I release my finger from the PB ( In case I use PB), They stop working. I want them to go on like I am using a Switch. Or As you say I want to latch them.

I using Delta 14ss2 PLC, and I am familiar with WPLSoft.

Also James I am trying to run a 3 Phase AC Elector motor CW and CCW, Is there a problem? please explain.

Quick note - you don't want us to bare with you, you want us to bear with you. One might bare one's soul, or one may bare a wire by stripping the insulation, but the most common meaning is to "get naked"

I believe what James is alluding to is that the PLC will do precisely what you ask. If you write a program to tell a motor to rotate CW for 1 second then CCW for 1 second, the PLC will happily do it. But any physical motor, especially with a load, cannot *instantly* change direction, as you have specified; it must accelerate and decelerate, and in the case of a large motor, those actions alone may take several seconds.

CW and CCW after adelay

Hi there

I managed to do the Job Following codes are the ones.( I basically added a Toggle Circuit to my Program)

But I have another issue at the Moment, and that is:

My PB Button now starts the program(even after releasing the PB Button), and It can stop it as well.

I do not want it to stop it, I know I should be able to do it using some kind of IF Commands, Basically If it is in On Position then bypassing

any other Push Action.

Any Help would be greatly appreciated


Also RoTaTech
Thanks a lot for advise, I sort of knew about this issue, I am planning to tackle it after my present problem.
On this issue If want to control the Acceleration, don't I need some sort of VFD, At present It seems to me that my AC motor do not have any, and it is doing the Cw and CCW action, Off Course i will go over it in more details in near future


regards

jhonansaro

jhonansaro,

your diagram is not labeled, what is the id of your pushbutton?

you WILL have the following issues.

1. what type of plc output are you using?
relay outputs have a life cycle span, so you must use solid state outputs.

3. NO 3 phase motor can stop instantly and reverse on demand.
depending on what the motor shaft is connected to and the coast speed to 0 rpm, will determine the time delay between going forward and reverse.

if this is a critical time, you might look into the type of motors used in a
tapping machine such as hypneumat or desutter.

even then, they have a time delay between forward and reverse of 1/2
seconds if my memory is correct.

when you run a motor in a direction you create momentum, torque, a magnetic field, and electrical current.
instantly reversing that direction will create an enormous torque on the motor housing, magnetic field, and electrical current.

james

In addition to the concerns mentioned above, you will have overheating problems unless you have a very special 3 phase motor. Do some research on "starts per hour".

CW and CCW after adelay

Hi there

The following codes work exactly what I want in the simulator, but it is not working in my actual PLC.

I should say it works once, but it doesn't Loop.

What could be the problem?



Regards