timed conveyer

[eastkodakguy]

completed ladders

I seems that the project was done way before I ever even posted the ladder diagrams. just thought I would give my prospective on it.
I was in school a few years ago and know how important it is to try to do it all on your on. Sometimes I could do it other times I couldnt. Even after she/he? did the the project, she/he can see how others might have done it. Its all about learning. bonkhead

 

[elevmike]

And here I was going to post a time based drum indexer. Do ya think that would have been a little much?

Or, read the inputs and write the outputs via BCD to the image regester.

 

[jessica]

guys its not nice too give this kind of remarks on female student what is it? can't you guys stand too have female student in plc? IN YOUR CASE GIRS CANT DO GUYS JOB ?I'M NOT BLOND FOR YOUR KIND INFORMATION YOU CANT MAKE BLOND JOKES ON ME.

 

[Mike Williams]

Look at it this way Jessica, if they had real programming jobs, they would not be on the forum all the time.

 

[Mtn_Bkng_Dave]

Good One Mike......

As I was looking through the solutions provided I was thinking the same thing........

Dave

Oh and BTW didn't they quit calling them drum indexers when they did away with the drum and bb's?

 

[Thomas Sullens]

Hi
In your ? about the Stop button the PLC doesn`t care whither it`s NO or NC, but for safety reasons. A Stop input should always come from
a NC input. The reason is if a wire breaks or dust gets in the contact
what ever it`s controlling will Stop.If you use a NO contact for a
Stop input and something fails, you will not know there is a problem.
Then it could be mucho peligorso.

 

[jshiepe]

I hope Jessica's not missing the point.....

Jessica,

I hope you didn't misunderstand the point of my post. Pierre made the observation that it seemed like you received A LOT more help on your issue than most male student posters we have seen here in the past. My post was actually meant as a humorous way to make sure you get fair and equal treatment, as you should be expected to put in just as much time and energy as everyone else. Unfortunately for you, this is a stigma that you will encounter intermittently throughout your professional career unless you can step up and earn the respect of your peers. I hope you wind up working with a group of people who will give you the opportunity to do that.

 

[elevmike]

The problem is that I did imagine her as a blond. Oh Well....

Jessica, dont worrry about the Girl-Engineer thing. My older sister's an engineer at the local utility company. She started off at the bottom and now is residing in one of the "richest" zip codes in the country. She tells me her house is paid for. I asked her to come to work for me and she laghed at me.

Keep up the good work, and dont pay attention to that ****. If you do it will only make it harder on you.

Mike

 

[cnrservices]

I just read through this thread from the beginning [the replies relevant to the original post] and have to add one item.

Don't ever rely on a timer to get something somewhere consistently.

Running a conveyor for 5 seconds and hoping the box is under a feeder (it may end up there 99.993% of the time, although) and starting the feeder to fill the box will undoubtetly have a customer calling you during dinner or a movie with the line shut off & half his employees cleaning a spill.

Before you start any operation towards any item - make sure it is there regardless of time. Motors go bad, drives bind & slow down, speed pots get turned - usually UP, chains & belts break, etc.

 

[elevmike]

cnrservices,

Jessica is a student. The assinged project is an exercise in the use of timers. Hopefully she get on to the reliability, and safety stuff latter in her studies.

 

[Sleepy Wombat]

In fact this was her second assingment, the first being the old traffic light problem..

 

[cnrservices]

elevmike

I realize this is a college project, but what better time to start doing things correctly; and, wouldn't any teacher give more credit to a student that thought through the process?

 

[elevmike]

cnrservices,

In my opinion your absolutely correct, and without a doubt.

In the conveyer application, or any conveyer application, The use of timers would not be a wise choice for positioning control.

However it is my understanding (I could be wrong) that the instructor presented a specific problem to be solved with specifically with timers. Therefore she must provide the assigned solution within the fixed resource pool that is allowed. Just last week or so she had a traffic light problem, (more timers). It seems that timers are on the syllabus at the moment.

In my opinion this is a bad example for the application of timers, however you know what they say about teachers... But it’s in the middle of the semester so she still has time to learn about sensors etc..hopefully.

Mike

 

[samson_ananda]

Solutions. Please check

Hello Jesicca,

I went through your project. I made the project on my Plc and also simulated it and it works perfectly ok.

You wanted to know whether the sensor comes before/after the push button. Do not have the sensor input in the same rung as that of the Start/Stop buttons. I do not know how you have done the Start/Stop Logic. But it is a good practice to have the inputs after the Start/Stop Logic in a different rung.

Well my solution is simple. Have the Start/Stop buttons in the first rung of the ladder. The output of the first rung will be at the start of every other rung. For example, the Output -( )- with address O0:1/2 in the first rung will be present at the start of every remaining rung as Normally Open Contact –l l- with address O0:1/2. This means that when you press the Stop Button, everything stops whether the sensor is actuated or not.

There are many other things you might have had to consider if this was not just a project and if this had to be actually been done in an industry.
1) The whole operation From the sensing of the bottle by the sensor ~Pushing of the bottle to the other part of the line by the cylinder takes up 17 seconds. This would have been a lot of time for a fast process. WHAT IF AN ANOTHER BOX COMES IN FRONT OF THE SENSOR IN BETWEEN???? You might be able to block the sensor (in the logic) till the process of one box is over. BUT what about the Conveyer?? That is still moving. It WILL move the other box at the start whether the sensor has detected it or not. In short, you will have to make another provision at the start such that another box does not come in front of the sensor, till the work of the first box gets over.

2) The project which you have mentioned has one sequence following by an another. The sequence starts with the detection of the box in front of the sensor and ends with the pushing of the box with the cylinder.
The conveyer moves twice during each process. First, during the detection of the box by the sensor ~~ till it reaches the first feeder. Second, after the feeding of the first feeder ~~ till it reaches the second feeder. The first movement of the conveyer takes up 5 seconds and the second movement takes up 2 seconds. IF BOTH THESE MOVEMENTS TAKES UP 5 SECONDS(OR SAME TIME), YOU CAN HAVE TWICE THE NUMBER OF BOXES PROCESSED AT THE SAME AMOUNT OF TIME AS BEFORE. GIVE THIS A THOUGHT. For this, the program changes a bit where you will have to enter the sensor output to the bitshift register and so on.

3) THIS IS ONLY FOR INDUSTRIAL POINT OF VIEW. I feel few addition steps are required at the start of your program incase you want to use an Emergency Switch or Stop push button. The moment you press the Start Button in the begining, the conveyer should move for few seconds & stop & then the steps/sequence( you mention in your projects should start). The reason is given below.
Incase the process(Box) is going on and if there is an electrical failure or emergency stop or normal stop, the box will be anywhere on the conveyer. It might be below the first feeder, second feeder, partially filled, etc. WHAT WOULD YOU LIKE TO DO WHEN YOU RESTART YOUR PROCESS? You have 2 options. 1) To discard the box or 2) To continue from where you have stopped. In both the cases the programming will become different.

Best of luck,
Samson

 

[rootboy]

guys its not nice too give this kind of remarks on female student what is it? can't you guys stand too have female student in plc? IN YOUR CASE GIRS CANT DO GUYS JOB ?I'M NOT BLOND FOR YOUR KIND INFORMATION YOU CANT MAKE BLOND JOKES ON ME.

Nope, no problem with females. You are neither a concern nor a threat.


Not out of any particular concern for your feelings, but out of respect for those among us who do not speak English fluently I withheld most of my original comments.

However, it's obvious that you cannot be bothered to take the time to come up with sensible questions (or even attempt to work out a solution for yourself), so I dare say that it is your lack of effort rather than a lack of understanding that is the root of your problem.

And then you get indignant when some of us give you a hard (?) time for your laziness.


So allow me to post my original response in its entirety:

Sigh, another student, more homework.

At least it wasn't a traffic light.


Since you have the attention of several fine programmers that are doing an exceptional job in helping you out with your logic, and therefore do not need my programming expertise (such as it is), let me slip into S.I. Hayakawa mode and chastise you for both your abysmal spelling and horrid grammar.

Your posts are rife with spelling errors, incomplete sentences, and fractured thought. Did you re-read them prior to submitting them? Do you have a spellchecker? Did they make sense to you? A “no” to any of these questions should be a tip-off that something is awry.

Before taking umbrage to my complaint of your communication skills, please take a moment of your precious time and critically re-read your posts for spelling, accuracy, and general readability. I think that you will find that your posts are nearly unintelligible and force your benefactor into gleaning your intent only after reading and re-reading your posts several times.

Maybe I am speaking out of turn, but I think that asking someone to come up with both your answer and your question is asking a bit much.

[/S.I. Hayakawa][/rant]

In short stop being lazy and do some thinking for yourself. Yes, this is the place to come for PLC help, but you will have to do most of your thinking for your own self.

As for me worrying about you entering the field, only if I have the misfortune to be near any of your equipment when it blows up.


Where's Terry when we need him?


John