Hello!Newbie here

Shock

Member
Join Date
Aug 2005
Location
kl
Posts
3
Hi, I am new in PLC. I am taking the course this semester in my college. I need some help.Thx for your kindness for helping me first.

I am using Omron PLC. I need some help on how to Write a basic Washing Machine.I know this might be too much, but i hope that will have a guide or example for me to have a look.My college provide the sample are all simple samples where i cant even write a simple washing machine. The samples are just teaching how to use Timer,Counter,DIFU,DIFD.

I Thank you for reading this although not posting.Thank you
 
Terry woods,
I have search the site, and i found washing machine plcs,but it is not under omron and i could not understand it.
 
Shock...

I sympathize...

Yes, it is true... most "solutions" provided here are directed at specific PLCs rather than at "general solutions".

Too many of the users here can't seem to discuss concepts without doing so in terms of there own particular PLC. That is a shame... so many (that don't use the particular PLC) are excluded.

If I were to describe a PLC-controlled Washing Machine to you... I would not describe it in terms of OMRON, or AB, or Mitsubishi, or Telemechanique, or...

I would describe it in terms of the basic control-concepts, using rudimentary logic. Then, YOU would have to figure out how to employ those concepts and rudimentary logics with your particular PLC... don't forget, even for a general PLC-type, there are many variations of that PLC.

After all... you are trying to learn about PLCs... aren't you?

If you have a particular PLC in hand, then you simply MUST study the manual and learn how your particular version of the PLC actually works.

But... aside from learning how that particular PLC is programmed, you really need to learn the basics of logic! Only by doing so is it possible for you to easily move from one PLC to another. But then, of course... you have to learn the ways of the new PLC and it's interface. However, having the basic concepts in mind, you now know what to look for in the new manual and interfaces.

The only thing that ALL PLCs (all reasonable PLCs) share is that they all can implement the same basic control-concepts... because, at the lowest levels, they all use the same primitive logical operations. These are not to be confused with vendor-specific functions.

It is NOT the case that all vendor-specific functions (across all PLC types) operate the same. Each vendor has their own way of doing things at the function-level. However, if the basic control-concept is understood then the desired result can be obtained without using the vendor-provided functions.

At that point, the only real difference between PLCs is in how each particular PLC is programmed. That is not to be confused with "how a particular process is developed"... any process can be developed without having any idea which PLC is going to be used.

What is lacking in almost all PLC Training classes is... "How to develop a Process".

Of course, the classes are simply to short.

There's more to automation than OMRON, or AB, or TI, or...

Maybe you can post your ideas on how the Washing Machine should be controlled. You would do well to do so in terms of the basic concepts rather than the particular OMRON Functions. Once you understand the concepts... then you can more easily figure out which functions to use.

Thanks for listening... good luck.
 
Developing a process isn't something a vendor will typically teach. A vendor is typically going to show you the ins & outs of their controller.

The advice Terry gives about concepts is dead on the money, and follows the cart/horse analogy very well.
 
As Terry and CroCrop said UNDERSTAND THE PROCESS.

Even as an electrician the first question of trouble shooting is
what is this thing supposed to do? THEN
why is it not doing it?
UNDERSTAND PROCESS

As a student who just completed two quarters of PLC and VFD AND wrote a program for a washer this will be a challenge - it is more complex than one thinks.

Sit down and watch a home unit run NOT LAUNDROMAT (too automated) - takes about 15 minute BUT will save you time in long run.

NOW
write down what you did to make run
1. Plug into wall socket
2. Turn on
3. Set timer switch to proper cycle

etc etc
write down cycle sequence
fill (hot -- keep it simple)
agitate
pump out
spin
fill (warm sorry but that is reality - open both hot and cold valves)
agitate
pump out
spin
done
NOW add a few safety features
what happens if you open the door - how and what do you interlock with?
often the motor reverses (or gears need to engage) - requires a pause time to let motor stop or get in gear - what are you going to do with this?

SAMPLE LOGIC for the fill warm cycle
open the hot valve AND open the cold valve UNTIL full
THEN translate these words into whatever program language (or ladder logic) you are using.

CAUTION
IF this is your first project I think you are biting off too much.
DO NOT let it get you down
- it is learning
- you WILL make mistakes
- you are a student you ARE allowed and expected to foul up.
- you will get frustrated

REWARD
when you get it done (or overcome major hurdle)
I CAN FIGURE THIS STUFF OUT
I DO HAVE A BRAIN AND IT DOES WORK

Dan Bentler
 
I got snagged into going up to Home Depot for... lunch... yeah, lunch (Hot Dogs!)

Anyway, Dan beat me to this but here is what I was gonna post just before I got snagged...


WASHING MACHINE
Set your controls
HOT Water, COLD Water, HOT/COLD Water
Fill Level Height
Auto-Soap Dispense?


FILL (Wash Water)
SOAK
AGITATE
ADD SOAP while AGITATE
CONTINUE AGITATE
STOP & DRAIN
SPIN to Finish Drain (Short Spin Time)
STOP & FILL (Rinse Water)
AGITATE
STOP & DRAIN
SPIN to Finish Drain (Long Spin Time)
DONE

TIMING DIAGRAM

OFF/ON +---------------------------------------------------------------+
---+ +---

+--------+ +-------+
FILL ---+ +----------------------+ +---------------------------

+---+ +---+
SOAK ------------+ +--------------------------+ +-----------------------

+------+ +------+
AGITATE----------------+ +-----------------------+ +----------------

++
ADD SOAP------------------++--------------------------------------------------

+-----+ +------------+
DRAIN ------------------------+ +-----------------------+ +---

+-----+ +--------+
SPIN ----------------------------+ +-----------------------+ +---


This provides a pretty simple washing machine cycle.

As a basic exercise, I should think that having the outputs come on is enough to simulate the cycle. That is, I wouldn’t think that you need to develop the actual mechanical & logical mechanisms to operate the washer motor (clutches and such).

At this point, the timing diagram above should introduce as many questions as it answers.
 
Shock

Well you got two versions of the same method
AND
you now also have the timing cycle.

Now go do some thinking and respond with a prelim design.

Dan Bentler
 
Well thank you guys for guiding me though all this.I will figure all this with ownselves. Thank you all once again
 

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