Lots of LogixPro Questions and Ideas.

Hi People,

I rarely use this forum, mostly because I like to try to learn things on my own and do my best to see if I can figure it out.

Heres my story. I work for a med sized company that manufactures Marking Equipment (Columbia Marking Tools) CMT for short. I do many things for the company but what I WANT to do for my career is to program PLC's. So a little while ago I purchased LogixPro Simulator II and have been working through the Student Excersizes found in the Help Menu. I have managed to work my way through nearly all of them except for a few hang ups now and then and I move on until I can come back to it and figure out my problem. Well... I've moved on as far as I can on my own and I think I'm in need of a little help.

I was first off wondering if anyone knew of a website or a book that I can read/buy that is like a Walk-Through of these excersizes, explaining all of the concepts and programming that is required in order to make the simulation work? If this is not possible, is there a support forum for them where I can ask questions directly related to the Excersizes and the Program?

Last But Not least, would anyone be willing to answer some of my questions and possibly help me via E_mail or IM of some sort? I am going back to college very soon but it's going to be a while before the classes I'm in catch me up to what I've already learned with this program and I'd like to get some help sooner than that.

Anyone can contact me at [email protected] or 1-586-949-8400 via my work cellphone.

I would greatly appreciate like a tutuor or group of people willing to help!

Thanks so much

Sincerely
Tim Ryder

Welcome Timryder

Why don't you want to post your questions here. There have been many Logixpro questions on the forum and then many can learn instead of one.

That is the point and spirit of the forum.

Click on download then Allen Bradley above , you will find several .rsl files. Also do a search for Lancie1, he has posted several examples using that software.
And as ndzied said post your question on the open forum, you will get a lot more help.

You like to live dangerously posting your phone# and e-mail on a world wide open forum. Good luck with that one.

Cool,

But Noone has ever seen an online walk-through of some sort?

Ok,

Here is my first question. In the Compressor Excersize2, I do not know what is the best way to make BOTH motors fill the tank. I though of using a Bit when compressor 1 is done that would prevent it from running again until compressor 2 has run. Then the cycle would repeat, but when I began programming this, I got lost and didnt know how to complete it.

Any one have ideas of a better method or a way that I can make mine work?

timryder,

The first step in writing logic is to put a discription down on paper. If you can describe it the rest is easy. Can you post the discription for us to see?

Absolutely,

Here is the process and how it will work. The requirement is that the First Compressor (C1) will fill the tank with air pressure on the the Pressure switch (PS1) reaches its desired value. When the (PS1) is On C1 will stop. Then when the volume of air in the tank becomes too low the 2nd compressor (C2) will engage and fill the same tank while C1 rests. Then when PS1 has reached desired value, C2 will stop and the entire cycle repeats.

timryder,

Are we sticking to the discription? Or are we talking real world with ooops! scenarios? Like the maintenance man has locked out the one of the disconects?

lol no if you have TLP LogixPro Simulator, I'm just trying to go through Excersize #2 for the compressor Simulation.

So its not real world.

Here is the excersize Description


Exercise #2 --- Alternating Compressors when Loading is Light

In this exercise, each compressor is to take it's turn bringing the storage tank pressure back up to the selected pressure setting. Pneumatic/Electric switch PE1 will continue to be utilized for this purpose, and the settings will remain the same as those used in the previous exercise.



The task of alternating back and forth between loads is sometimes referred to as a load toggle function, and there are numerous methods to accomplish this in relay logic. In this exercise however, you are asked to limit yourself to using only basic relay type instructions when creating your solution.

Prior to testing your program, adjust the system's discharge flow rate again to 50% as shown. As we have already determined, this flow rate can be readily maintained by a single compressor. Adding a second compressor however, will share the loading and allow for an extended cooling period between cycles.

Once you have created your program, download it to the PLC and thoroughly test out it's operation.

Finally, adjust the flow rate which controls the amount of air leaving the storage tank to 80% and then 100% and note the effect. At higher rates of flow, a single compressor will not have the capacity to supply this system's peak needs on it's own. Obviously we will need a bit of help at times from the second compressor.

timryder said:

you are asked to limit yourself to using only basic relay type instructions when creating your solution.

Click to expand...

OK! We will try to stay in this format.

timryder said:

I though of using a Bit when compressor 1 is done that would prevent it from running again until compressor 2 has run

Click to expand...

Do you know how to program a seal in or latching "relay"?

If you do. Can you figure a way to make it seal itself or latch and then un seal or un latch by way of the pressure switch?

I know the term "Latch" like for instance an Output Latch or I can Latch a Bit on.

Greetings timryder ...

take a look at the program attached to this post ... while the requirements aren't exactly the same as the project that you're working on, they are quite similar ... I've got a hunch that the methods which the VACPUMP program uses will be helpful ...

the main concepts:

(1) first specify exactly what decisions your program needs to make (which pump to run, etc.) ... then set or reset "internal" bits (example: B3/0, etc.) to "mark" or "record" those decisions ...

(2) then finally use those "marker" bits to actually turn the pumps on or off ...

many people refer to this programming method as "abstacting" the ideas ... some programmers swear BY this approach - others swear AT it ... see what you think ...

and just in case you don't have the RSLogix500 software available, I've attached the file as a PDF at the very end of the original thread ... I've been asked for this particular program in a PDF format quite a few times over the years - I might as well go ahead and post it ... hopefully it will help you as much as it's helped others in the past ...

I don't know the logic set of logix pro, so I'm going to give you a generic way to do this. If you have oneshots, set and reset, positive transition or negative transition contacts or positive differential coils this could be different and easier to understand. I'm pretty sure this will work in your program

Can you discribe what is happening and how? Hint: think abou how the plc scans the logic.

Here's what it looks like

Here is a screen shot of what I'm working with and my logic thus far. You can see the simulator as well.

here is the link of best free PLC ebook available on net. One more good thing is - it is written mainly on Allen Bradley PLC. Hope it will help you a little.
http://www.eod.gvsu.edu/~jackh/books/plcs/
regards,