New to PLC - Please help

Hello All:

I am working on my first PLC Program, using a Keyence KV-24DT. I bought and viewed the videos, and have several questions that will probably seem a little silly, but first let me describe the equipment.

The machine is a vision system that will detect the accuracy and legibility of a printed stamp, and the correct lid using a 2 camera keyence CV2100 vision system. The base is an 8 station rotary index table. Below is a brief description of each station:

1. Operator loads part
2. Part presence sensor
3. Automatic pad printer
4. Camera 1 - stamp inspection
5. Camera 2 - lid inspection
6. Reject - Bimba cylinder with 2 MRS sensors (top and bottom)
7. Eject - (good parts) bimba w/ 2 sensors (top and bottom)
8. No activity

Question # 1: How do I index the table when I cannot use the same coil more than once?

I'll stop here for now.

Thanks,

David

What do you mean cannot use the coil more then once?

I think "YOU THINK" the coil needs to be in sequence every time an action occurs...NO.

You condition a rung to activate an output when needed...Example
system ready, parts loaded, OR part has been rejected ready to index...then index. This allows 2 different conditions to activate the indexing...ie start up then as needed in the sequence.

Thanks.

Question # 2: Suppose a part is rejected by the vision system. How do I program the PLC to actuate the cylinder valve, and where is the best place to place the logic? In other words, does this condition fit on the same wrung as the camera that rejected the part, or is this a different wrung altogether?

Question # 3: Is anyone willing to help me out over the phone? I am lost.

Does the PLC have a shift register function, if so, the advance the register every time you index the table, then depending on the way the shift works, deal with the good/bad stamp.

By the sound of Q3 though, you need someone with more PLC exp than you have, or at least exp on the PLC you are using.

Scott, it does have a shift register function, but I am not sure what to do with it.

The shift register function asks about operands. What is the concept here?

I am not familiar with your PLC type, but a shift register is exactly that, it shifts bit left or right depending on the type. It is up to you to deal with these bits in relation to your application.

I think that by you asking about operands, this project is a bit to complex for your first one. What electrical / mechanical experience do you have?

You seem to understand the concept of your application.
Have a look at some of the tutorials on this site, they will at least explain the way a PLC works, it may be worth doing an introduction to PLC's course however.

Let me look at the PLC you are using and then I should be able to break it down for you. (get the terminology right)

The shift function for the Keyence PLC you are using has three inputs D, CLK, and RES and uses two operands which can be memory locations 1000 thru 1915. The operands set shift register. Say that you assigned DM1000 to the first operand and DM1010 to the 2nd operand , assign input 0000 to the D, 0001 to the CLK, and 0002 to the RES. When the RES input is on the memory locations from DM1000 to DM1010 will be cleared or all set to zero. If you set the D input to on and toggle the CLK input once then DM1000 will be on and the rest off. Turn off the D input and toggle the CLK input again and DM1000 will be off and DM1001 will be on. DM1002 thru DM1010 will also be off. As you toggle the CLk input the data will be shifted. If the D input is on at the time of the CLK input then a One will be shifted into the register. If the D input is off a Zero will be shifted into the shift register.

You might want to visit the Keyence web site and download the programming manuals for these PLCs. As for your project good luck. Since this is your first project I suggest that you take the time to plan out how you are going structure the PLC program on paper before you get into the actual programming. Your project is not that difficult and should be a great learning experience.

roelandr2 said:

Your project is not that difficult and should be a great learning experience.

Click to expand...

That's what I thought, but I really don't understand what you just wrote. Let me get the manuals to learn what "D", "CLK", and "RES"
mean.

I should finish assembling the equipment by Friday. I think with what little knowledge I have, I may have better luck programming one station at a time, here I can actually see the program work. One (of the many) problem I am having is knowing whether I have a wrung that is correct or not. I don't have the luxury of hiring a programmer, and can't afford to take the time for a class, so I have to keep chipping away at it, and being automation/electronics illiterate isn't helping.

Thanks to you all. Please don't stop replying. I am trying to soak it all up. Try to use laymans terminology.

David

scottmurphy said:

I am not familiar with your PLC type, but a shift register is exactly that, it shifts bit left or right depending on the type. It is up to you to deal with these bits in relation to your application.

I think that by you asking about operands, this project is a bit to complex for your first one. What electrical / mechanical experience do you have?

You seem to understand the concept of your application.
Have a look at some of the tutorials on this site, they will at least explain the way a PLC works, it may be worth doing an introduction to PLC's course however.

Click to expand...

Scott,

I have very little electro-mechanical experience. I bought the videos from the site, and they explain how a plc works, but doesn't tell how to program them. How could they? There's too many different kinds of applications. I understand the number systems, shifting, etc., but don't know how to tell the PLC to shift 2 stations if the part is good, and 1 station if it is bad.

Like I said, as long as you folks don't mind replying, I'll eventually know how and what questions to ask. I have to get this thing programmed within 1.5 weeks.

Thanks for your help.

as was asked before, what is your level of electrical/mechanical skill? The reason this is asked is because programming is no different than designing a panel using relay logic. You have to understand how to manipulate the data to get the result you want. An operand is an object to be manipulated.

If this were a different type PLC, I could be of more help. However, the distributor that sold you the Keyence should be familliar enough with it that he/she could guide you through the basics.

oh boy; 1.5 weeks to learn PLCs and create a running machine...

I know nothing about a Keyence so I'm probably not going to be much help, but the distributor that sold the Keyence should be able to help.

If you know any computer programming languages then start off with a list of if/thens that will get what you want done. Keep it simple, yet detailed; this is just so you have a good reference to what is supposed to happen on each rung (you can think of a rung as an if/then statement).

Try the Keyence website, e-mail them or call them directly. Apparently they offer free programming literature, a cd and may offer free technical assistance to their Customers.