Help, please explain a PLC program to me

[davidgeorge212]

Hi, I am new to PLC's and I have a program that I need a little help with an explanation of how it runs line by line. I understand the overview of what it does but I would love if someone could break it down line by line and tell me how it is operating.


Thanks, David.

 

[davidgeorge212]

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[davidgeorge212]

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[TConnolly]

Greetings David and welcome to the forum.

Do you have a copy of the .ACD plc program file. The pictures you posted aren't very clear.

 

[harryting]

RsLogix's Instruction Help explain each instruction in detail. To understand the system and put it in context we need:

- Functional Description.
- P&ID diagram
- Electrical diagram.

eeks, MCR and JUMP... I sure hope this isn't a real program.

 

[davidgeorge212]

I will see if I cant obtain the actual program file if not better pictures later tonight. Those were actualy scanned copies of printed black and white photos.

 

[davidgeorge212]

RsLogix's Instruction Help explain each instruction in detail. To understand the system and put it in context we need:

- Functional Description.
- P&ID diagram
- Electrical diagram.

eeks, MCR and JUMP... I sure hope this isn't a real program.

It is a program that runs a trainer robot arm, a conveyer and a rotating rack. It is supposed to spin a rack around that has 18 slots in it. The robot arm is supposed to pick a part off of the rotating rack then put it on a conveyer belt. Once the part is on the conveyer belt, it travels around underneath a camera and the camera checks to see if it is a good part or a bad part. The part then travels back around to the robot arm and the robot arm is supposed to pick up the part and place it back on the spinning rack on either the good or bad shelf (A or B).

 

[Ron Beaufort]

we'll help if we can - regardless ...

but ...

I've just GOT to ask ... are you a student, an instructor, or a lab technician, or ? ...

please note that you'll have to ZIP the ACD project file before you can attach it to this thread (that's just a forum rule) ...

and one more quick question ... is this thing currently WORKING the way it is - and you just want to understand it? ... or ... is it malfunctioning - and you need to FIX it? ...

 

[davidgeorge212]

Hopefully the .ACD file loaded properly. Yes, I am a student and im fairly certain that this program should be working. It was programed to run a classroom trainer setup. I am just interested in learning more about how it works and what its doing in the program.

 

[davidgeorge212]

Here are a few shots of the setup in the classroom. The conveyer track is in the front to the left, the cognex camera is on the back side of the conveyer. The robot arm is on the right side and it slides back and forth from the spinning rack in the background to the conveyer belt. I think on the spinning rack in the back, there are 3 shelves and it spins around and there are 18 slots.

 

[OkiePC]

THAT, is a sweet trainer I must say.

I will now have to peek at the code in jpgs above since I can't afford a personal copy of Logix5k.


13 pages printed...intriguing. I will have to come back for the .acd version if he posts it.

@davidgeorge212: Have you seen the machine operate running this program? Can you describe how it behaved in detail?

 

[davidgeorge212]

I have not seen it operate in person. At our school we have a 2 part PLC course, I guess you could call it beginners and advanced. I have only taken the beginners course so I only have a basic knowledge of PLC's in general. I cant tell you exactly how it is supposed to work but I only have a summary from what others have told me. The middle robot arm is supposed to slide forwards and backwards on a track and it is supposed to pick up an untested part from the round spinning rack in the back. It then takes it over and drops it in a little cart on the conveyor which is supposed to then start up and travel around underneath the cognex camera. The camera is supposed to determine if it is a "good" part or a "bad" part. When the part on the cart travels back around to the robot arm, I think it is supposed to pick it back up and put it on the top or middle shelf or "good" or "bad" shelf. Then I think it may repeat and keep doing it. That is just the description that I have heard, it may vary a little. Thats just why I wanted to see if someone else could help me interpret the program and tell me a little more about what it does.​

 

[davidgeorge212]

The last couple of pictures I posted were of the main box control panel (which also contains the PLC inside). In the program it refers to certain pilot lights and push buttons. This is the panel that runs it if that helps.

 

[bernie_carlton]

Here's a PDF printout

 

[Ron Beaufort]

it would really be helpful to know (for sure) whether it works or not ... if it DOES then there's a good deal of "cleanup" that could be done to make it more readable ...

for one prime example: it doesn't make a lot of sense to JSR (Jump To Subroutine) – just to do one single MVM operation (Masked Move) – and then use a superfluous RET (Return) ... see the Bad Part, Good Part, and Pick routines for examples ...

also ...

there's nothing in the Robot program at all ... is this a "work in progress" – or is the robot piece of the puzzle being handled by some other controller? ...