Class Project

Notes:

If you must use LogixPro, there are some limits on your project.
1. You must not use Input and Output addresses that are not included in LogixPro.
2. Your inputs are 16 discrete in slots 1, 3, and 5. Slot 5 can be used for a BCD number input also, as from a thumbwheel switch.
3. Outputs are limited to 16 discrete outputs in slots 2, 4, and 6. Slot 6 can be used to show a BCD number, as an LED number display.
4. No analog inputs or outputs are available in LogixPro.

A project that could use all the instructions on your list (plus some others like OSR) would be a vending machine with money changer.

from rsdoran:

I am sure Ron had his own reason for asking, i.e. to get the OP to respond what out was but bet he understood what it had to be in reference to the other instructions.

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precisely ... in context it HAS to be OTU (Output Unlatch) ... my only reason for asking was to make the point to Plexico that in this trade DETAILS are extremely important ... now I’m NOT trying to knock Plexico’s spelling and grammar - but so far his posts have been full of misspellings and other assorted errors ... is that an issue? ... no, not in the context of the forum ... and as long as we can fully understand what he’s saying and asking, we do NOT care ... and that’s why I ignored EVERY error he made - except for the one in the instructions list ...

SO - the “point” ...

when it gets around to “programming” time, a “misspelled” word (or an incorrect address) in the PLC program can make quite a fine mess of things ...

summing up ... Plexico, we humans can afford to be very forgiving of your spelling mistakes - but remember that the PLC will NOT be so understanding ... so if your new program doesn’t work exactly the way you expect it to, one of the FIRST things to check is your typing ... you’re going to have to be very careful in this area when you work with the PLC ...

finally ...

do you know why you would need to use "latches" and "unlatches" as opposed to something like a "seal-in" construction? ... and why would an RTO be used rather than a TON? ...

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that’s a question that I asked back in post #9 ... Plexico hasn’t answered that one yet ... so maybe he doesn’t understand the R-word concept ... if I had to guess, the instructor has already explained that particular concept - and now wants to gauge how well the student has grasped the major ideas ... that’s probably why he’s requiring the use of the OTL, OTU, and RTO instructions ... sort of like: “whether you NEED them or not, USE them in your program” ...

let’s be logical here, folks ... the instructor does not NEED a new dishwasher program - or anything else that his students are going to come up with in this exercise ... all he’s trying to do is force the students to touch / feel / handle / work with / experience / become familiar with / practice with / all of these basic common ladder logic instructions ...

it’s like the first lesson in a carpenter class - to build a bird house ... we don’t NEED the bird house ... what we need is for the student to get used to the hammer, the saw, the drill press, etc. - in other words, the tools of the trade ... so even if the bird house (or the new PLC program) turns out to be a piece of junk, the lesson might still be a rousing success - as long as the students learn how to (or even how NOT to) use the tools involved in the building/programming process ...

Make it simple.

A toaster is simple. Then add something to count how many slices of toast you've made and what the total time of use is for the toaster. That will demonstrate the use of retentive timers and counters. Make the toaster wait to eject the toast for a couple of seconds after the elements shut off to demonstrate use of a TOF. Add some flashing lights to indicate heating and/or done. Last, your toaster requires cleaning after 100 slices of toast - a chance to demonstrate a count down.

It doesn't have to exactly model the toaster you made breakfast with this morning or model a realistic appliance.

Great ideas, Alaric. This would be the New Improved PLC-Controlled Toaster.

Lancie1 said:

Great ideas, Alaric. This would be the New Improved PLC-Controlled Toaster.

Click to expand...

A PLC controlled toaster... well the way I programmed it

Looks like your PID needs a little tuning

OZEE said:

Looks like your PID needs a little tuning

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In my experience, maybe 'A' Shift prefer their toast done like that.
Of course 'B' Shift like it hardly warm and 'C' Shift prefer it somewhere in the middle.

PID Tuning is in the eye of the beholder ... I guess.
I GUARANTEE if you could mess with PID tuning in a toaster, operators would do so.
Then complain how the other shift dont know what theyre doing.

OZEE said:

Looks like your PID needs a little tuning

Click to expand...

Hey OZEE,

My dentist likes my PID tuning... he says it removes my plack buildup

SEE -----> <-------

Alternatively, consider a cofee brewing machine.

Since each batch should be for a certain number of cups, there will be a flow meter. This flow meter is a paddle wheel, and it provides one pulse per rotation, and since this is imaginary, we can pick whatever spec we want so 8 rotations is one cup of water, or 1 pulse per fluid ounce. Since the cofee maker brews one quart, we only want to add 4 cups of water, so we count 32 pulses from the flow meter to tell us we have added one quart of water, demonstrating the use of an up counter.

Our cofee maker can only make a certain number of batches before the filter needs to be changed. So you can demonstrate the use of a down counter.

No one likes an old coffee pot, so after a couple of hours we need a light to tell us that the pot should be emptied and a new batch brewed. You could demonstrate the use of a retentive timer or an off delay timer here.

Thanks but he gave us a assigment

Thanks but I guessing a lot of students of emailed him so he sent this out in a email so I done it.







Some of you might be having a problem coming up with a project. If you are, you can complete the following.



Mr. PLC's Buggy Bath Car Wash



The vehicle pulls up to the automatic attendant



The customer inserts coins or tokens for the wash and they choose one of the following

Input 1 (Basic Wash)

Input 2 (Basic Wash with Dry)

Input 3 (Wash and Wax with Dry)

Input 4 Super Wash (Wash, Wax, Undercarriage, and super dry)



After wash cycle is selected, a "drive forward" light comes on



Once vehicle reaches the correct position in the car wash, a "stop" light comes on (limit switch)



If input 1 was chosen:

"Wash" light comes on

High pressure wash comes on and washes for 8 minutes

Wash light goes off and "Rinse" light comes on

High pressure rinse comes on for 4 minutes

Cycle is over and an "exit" light comes on to indicate to the customer to move out of the car wash



If input 2 was chosen:

"Wash" light comes on

High pressure wash comes on and washes for 8 minutes

Wash light goes off and "Soak" light comes on

Soak cycle for 3 minutes

Soak light goes off and "Rinse" light comes on

High pressure rinse comes on for 4 minutes

Cycle is over and an "exit" light comes on to indicate to the customer to move out of the car wash

While the vehicle is exiting the wash, three heaters/dryers come on (show as dryer lights in this example), these stay on for 3 minutes





If input 3 was chosen

"Wash" light comes on

High pressure wash comes on and washes for 8 minutes

Wash light goes off and "Soak" light comes on

Soak cycle for 3 minutes

Soak light goes off and "Rinse" light comes on

High pressure rinse comes on for 4 minutes

Rinse light goes off and "Wax" light comes on

Low pressure wax comes on for 3 minutes

Rinse light goes off and cycle is over and an "exit" light comes on to indicate to the customer to move out of the car wash

While the vehicle is exiting the wash, three heaters/dryers come on (show as dryer lights in this example), these stay on for 3 minutes



If input 4 was chosen

"Wash" light comes on

High pressure wash comes on and washes for 8 minutes

While the vehicle is being washed, an undercarriage wash comes on and washes under the car

Wash light goes off and "Soak" light comes on

Soak cycle for 3 minutes

Soak light goes off and "Rinse" light comes on

High pressure rinse comes on for 4 minutes

Rinse light goes off and "Wax" light comes on

Low pressure wax comes on for 3 minutes

Rinse light goes off and cycle is over and an "exit" light comes on to indicate to the customer to move out of the car wash

While the vehicle is exiting the wash, three heaters/dryers come on (show as dryer lights in this example), these stay on for 3 minute



Each time a vehicle goes through the car wash, a counter will determine how many vehicles were washed and the total number of choices (1,2,3, or 4) that the customer had chosen.









This is what I Done If you all have any suggestions to it please feel free to comment.

Plexico,

It is a beginning. Now add to it and revise it so that it meets the customer's specifications (your teacher's instructions in this case).

(1.) You need to learn how to make an outline of your program. Start by listing all the Outputs that are needed. Your instructor DID mention almost every output that you will need. Insert rungs for each Output. Then look for major cycles, stages, or routines that can split the program into smaller parts. Now list all the Inputs. Then ask: "How can I use these Inputs to make the Outputs perform as instructed (for each stage)?" What other instructions will I need to make it work?

(2.) In Rungs 000, 001, 002 you do not need the seal-in contact on the parallel branch with your Input. Can you find out why you do not need these (in these specific cases)?

(3.) If Input 1 is on, High Pressure Wash should come on and wash for 8 minutes. It does not. Then Wash Light goes off, and Rinse Light goes on. Then the High-presure Rinse goes on for 4 minutes. None of these things (Outputs) are covered by your program.

(4.) You also did not implement routines for Input 2, Input 3, or Input 4. Four subroutines would work well here, using the SBR, JSR, RET, LBL, and JMP instructions. All these are available in LogixPro. If you don't know how to use these, then you will have to write sets of rungs (routines) that do the same things except without the help of these powerful commands.

(5.) Insert a new rung for Counter C5:0, so that "each time a vehicle goes through the car wash, a counter will determine how many vehicles were washed.."

(6.) Insert 4 new rungs for Counters C5:1, 2, 3, & 4, so that "the total number of choices (1,2,3, or 4) that the customers have chosen" will be recorded.

(7.) Add rung comments to each rung. Explain what the rung does, how it works, or any other item that needs documenting.

hmmm

I may not have done it the same way you would have and I think you for the help and I understand that i need to doc it a lil more but the program I worte works completey fine and meets all the cretiera. Actully my instrucer was inpresed to see that I accomplished the same thing he did in about 10 rungs less than he did. also my timers are set to like 8 sec insted of 8 mins in the pic of the rungs I sent adn 6 seconds instend of 6 mins and so on. done this just to speed up the simulation, didn't wan tit to take 20 mins to run though one cycle when I check for errors, I also assumed that he ment total number of choices not total like if he choices the first choice it counts up one if he chouses the super wash it counts up 4 and that how i done the sencond counter, and the otehr counter is just every time a wash is setelcted

Is that all the logic you wrote?
There are no release mechanisims for the latches.
There will be some unintended consequences if you leave it as is.

I don't know about your instructor, but mine would have given me a big fat F for that one.

no i worte 20 or 21 lines of logic for some reason the pic is getting cut off not sure why its whit in the size limits

Sounds like a job for Smoke and Mirrors!!!!!

David