Programming help

I am having trouble doing a washing machine program that needs to go through a process of fill, prerinse,drain,fill,wash,drain,fill,rinse,drain,spin.
everything is fine except I do not know how to get the process to continue once the door is open and then shut it would nee to be where it left off including time left on current cycle. it is for gefanuc.

Show us what you've done so far. We can try to steer you in the right direction. If you've set up your program as a series of steps and transitions, then you can include the door sensor in the logic for every transition. If you've used a master timer then interrupt the timer while the door is open. If you just sat down and started programming without first developing a plan of how to approach the task, then it may be challenging.

There is more than one way to skin a Cat.

If you have developed your program using the real Inputs and Outputs then its kinda hard to Stop these Outputs without also reseting there holding contacts.

Wow! Did I say Reset?

You could have a shadow code wich would follow your sequence with internal Bits and just move them Bits to the real Outputs when you have the door closed.

When the door sudenly opens, what will you do with the timers?

And what if ........

I am with Steve, show what you have so far.

A clue tho is look at using timers that must be reset.
Use the door input to stop the timers from timing and turn off just the outputs.

Also I should mention that I have all the cycles stored as an integer in an R location where a counter begins and I am moving them into the Q ouputs through the count by means of an array function. I was having trouble uploading the file to here but I will try it tomorrow from the original computer it is on for some reason my ftp site is down.

Thanks for the few ideas so far .

Wow!

This is a pretty interesting challenge for an assignment. For anyone who thinks this is an easy assignment consider the problem. When the wash machine door opens, the cycle needs to pause. But, the cycle must continue where it left off. So, you can't let the door reset your timers!

There are a few ways, off the top of my head, that this could be done. I don't know GE/Fanuc, so these are generic suggestions.

1) Use a retentive timer instruction if it is available (and allowed by the assignment).

2) Dump timer accumulators into holding registers while the door is closed. Reload this data on the rising edge of the opened-to-closed transition of the door's limit switch.

3) Use a one second timer as a periodic pulse to a bunch of counters. The counters don't get incremented if the door is open. If you use this solution the instructor might not like it. He probably wants the machine to run for EXACTLY the "right" amount of time. Even though it's a cool solution, he may not care for getting "close enough." If you try this method, be sure to tell the instructor that he didn't specify a tolerance in the assignment.

AK

I will also give you a bit of background on the actual program. It is supposed to be based on a simple drum that is in commom use in washing machines. The amount of time things happen is somewhat not as important as the process itself as far as tolerance is concerned. I am sure if it soaks for a few seconds longer no big deal. Or if it spins and so on. Retentive timers are ok to use and I am familiar with them. I am actually going to start over tonight with what I have so far and try to post it on here. Once again thanks for the replies so far.

Originally posted by plcnewbie
.... The amount of time things happen is somewhat not as important as the process itself as far as tolerance is concerned. I am sure if it soaks for a few seconds longer no big deal...

Click to expand...

.... Mediocrity - It takes a lot less time and most people won't notice the difference until it's too late.

Click to expand...

Please start your journey on the wright track. Make the thing do EXACTLY what you thinck it should do. Now.

Thanks for the response man but how about maybe a little help and maybe a little less criticism. So far everyone has been great but I guess I will never understand the people who scan boards just to make a snide comment and then thats it.?? Sorry if I offend anyone I know Im new but that is just my opinion.

Anyhow I have attached the process thus far that I have rewritten. The cycles are stored as R values as mentioned before in the vdt and moved into the array as each cycle completes. I am considering writing each line and have maybe a positive transition coil at the end of each to increment the counter.I obviously know this would require each to be a seperate coil as not to confuse the PC, therefor reguiring as many contacts in front of the counter as cycles if not more?
As far as the cycles they will be seperate as far as the timers (retentive I think)Would they hold when the door is open and resume when shut? I have nothing at home to run a test on yet? From there before they start I will do a compare statement to make sure the count is correct in order to start that portion of the cycle. Would anyone recommend using jump commands at all to maybe move in and out of a cycle when the door is open and the count is at certain values say above 1? I am not the best at jmp cmds yet.

Thanks again

Pierre said:

Please start your journey on the wright track. Make the thing do EXACTLY what you thinck it should do. Now.

Click to expand...

I posted method 3 because it still produces a working washing machine, but it's the kind of creative solution that college professors hate. It would still get your clothes perfectly clean, isn't any more complicated than the other choices, and it's not a software shortcut.

But I know from experience that a college professor would look at #3 and frown. If the cycle runs 12.01666 minutes instead of 12.00000, does it matter? Not on a washing machine. Other equipment is more sensitive. Understand your objective and design to it. A high speed timer could give you extra precision.

Another, very UGLY, solution to this problem would be to program it like a state machine and add states for "in wash cycle - door open", "in wash cycle - door closed", etc... That would be a good exercise, but a lot of wasted time.

AK

Personally have not done a washing machine, maybe I should and post it on the other site.

This is personal opinion and nothing else.
This could be like a drum sequence but I would not use the drum sequencer GE provides unless its required.

I would initiate a timed event sequence with door open able to pause the sequence. This sounds professional etc but in actuality only requires one timer...personally that would be an OFDTR. I would use the timer ON bit to start the fill till full (this could be compared to a specific time), then goto next event...if door is open at any time it stops timer from accumulating and outputs are off, this just requires placing --| |-- in the rung just prior to the timer or output.... assuming the door input is wired normally closed.

Right now I am more or less rebuilding my trucks engine. If I get time I may do the washing machine in VersaPro and post it.

I dont much care what anyone says about doing it right when learning and the application can not hurt anyone...NOONE ever learned from doing everything right. Do it any way you can to make it work...then work on making it better.

I reckon I am doomed to do the traffic light and washing machine.

GE Drum Sequencer

RON:

I had GE 9030's with drum sequencers at one plant rammed down my throat. Probably well over a 100 machines with them, all relatively similar.

I got used to them, but would have prefered regular ladder logic.

What in particular don't you like about it?

regards.....casey

cont.

We are not supposed to do the drum sequencer or it would be cake for me. I like your idea about the timer. I have done the traffic light thing too it is actually quite simple at least the one I did. Unless you want to add the inductive sensors to change quicker if a car arrives? I would just shift through an array and keep it cycling.

The task of washing closes is simple. For all I know you culd just call your Mom and drop by for lunch.

You are a beginner and you MUST learn to do these thing the good way.

There are many way to code this but there is only one way that this washer will work. Thats the way YOU want.

First, gather all the variables you can tinck of.

1. Door swotch
2. Level switch
3. Cycle selection
4. Start button
5. ... and more ...
   [/list=1]
   
   When I wrote about mediocrity, I wanted to mention to you that you must not cut corners. You write down what you want the machine to do and you make it do it.
   
   Not almost, not close, exactly what you wrote down.
   
   If you want a 2 second delay before it restarts after you have closed the door then you use a 2 second timer. How hard can this be? Is this to much for you?
   
   No write down ALL THE SEPARATE STEPS in your sequence.
   
   Take then one by one.
   Its a darn sequence. No multitasking here!
   
   

   ...I do not know how to get the process to continue once the door is open and then shut...

   Click to expand...

   
   I already gave you the answer in my first post. Before writing code you should learn to read.
   
   Perhaps its my english that is so bad.
   
   Being kicked in the ars can only make you leap forward. That's unless you fall down and cry.
   
   Remember Lara Croft's moto << I fall down, I get back up >>

Sounds to me everyone has ideas....
NO comment on this step logic problem.