Is it possible to learn PLC's yourself??

I would say it would depend on the individual. If you have the IQ of a sandworm or from South Carolina :), then I doubt it. However if you have the motivation, basic problem solving and reasoning skills and some type of support system then you should be able to learn it. You will not be able to open a book and pick up all the knowledge you need, you will need extensive hands on expierence.
 
I agree with Mark it would depend on the individual. I've seen many people take a PLC course(s) and still can't get their head around fairly simple logic so I would say you could get away without a course but it might be hard to get a opportunity. A lot of it is the ability to understand the process and the problem they have in front of them and the confidence to try your solution. No book can give you the experience of being at site for a startup in a control room at 2am with alarms blasting all around you and everyone in room looking to you because it's not always quite time in your office.
Can you understand code written by others to the point that you could modify or rewrite? That would be a place to start.
 
Simple answer is: Yes, you can learn to use and program PLC's by yourself.

The difficult part to learn by yourself would be some of the right and wrong ways of doing things. Example:
1) The need to for your program to interlock solenoids so both can't be on at the same time (think EXTEND/RERTRACT).

2) Stop buttons should be wired to N.C. contacts

3) Programming in a manner that someone else can follow you and easily figure out what is going on.

Have fun!!
 
Sure you can learn how to write code for PLCs. The difficulty in learning is to write clean, clear, concise, and safe code.

Regardless of classroom or self-paced this involves making a lot of mistakes and learning from them. Just finishing a class or reading a book isn't the end of your education.

Also, learn from others' mistakes. That is what instructors can help with. It's what groups like this are good at too. You get real world experience without having to make the mistake yourself.
 
Thanks for your quick replies. My background is that i have a honours degree in Physics and have been for 5 to 10 years writing code in Labview and using there versions of PLC's. The software i have written was for test rigs and R and D test plants. I know i have a good grasp of industrial control and instrumentation. Just wonder if this is a good base to get into the PLC control arena (diversify).
 
dogleg43 said:
Simple answer is: Yes, you can learn to use and program PLC's by yourself.

The difficult part to learn by yourself would be some of the right and wrong ways of doing things. Example:
1) The need to for your program to interlock solenoids so both can't be on at the same time (think EXTEND/RERTRACT).

2) Stop buttons should be wired to N.C. contacts

3) Programming in a manner that someone else can follow you and easily figure out what is going on.

Have fun!!
Click to expand...


Stop buttons is not always N.C.contact,you can use it even N.O.contact.It depends to Programmer/Technicians can control or connect it.

Respectfully yours,
RR
 
Riche Robledo said:
Stop buttons is not always N.C.contact,you can use it even N.O.contact.It depends to Programmer/Technicians can control or connect it.
Click to expand...
Sure an NO contact could be used but there's a reason it's the industry practice to wire it to a NC contact.

With an NO contact, if a wire falls off when the machine is running you can't stop it.

With an NC contact, if a wire falls off the machine stops.

Same concept for why a start button is typically NO. Wire falls off, machine doesn't start by itself.
 
Riche Robledo said:
Stop buttons is not always N.C.contact,you can use it even N.O.contact.It depends to Programmer/Technicians can control or connect it.

Respectfully yours,
RR
Click to expand...

Well of course you can. You can do just about anything you want. Is it a good practice? No.

By using Normally Closed contacts on your stop switch, you make the component more fail safe. if the cables going to switch get severed or the switch gets smashed, the machine will stop.
 
Lancie,
I don't understand you're response. Are you saying it's wrong to wire STOP buttons to N.C. contacts?
Click to expand...
Your question ASSUMES that STOP buttons are wired to some type of contact. I say that a better assumption is that STOP buttons usually OPERATE a normally closed contact. The STOP button is not wired to any contact, but the contact is an integral part of the button and is operated by the button - no wiring required here! The wiring is in the next part, from the STOP button contact to the PLC Input terminals.

Where you made the wrong assumption is: that you wire this Normally Closed Stop button to a PLC input, and then inside the PLC program, you would not use a NC, but instead a NORMALLY OPEN contact to examine the Normally-Closed-Stop-button-input. Only a PLC "normally open" instruction will show that a Normally Closed STOP button is actually closed.
 
Last edited:
Personally I think you have missed the point which Lancie1 was trying to make.

OK I tend to agree that a N/O should be used for a start switch and a N/C for a stop switch, but you are making the assumption that everyone does this.

I have seen machines wired completely the opposite.

Now you are ASSUMING that a normally open switch will always have a XIC instruction associated with it.

And you are ASSUMING that a normally closed switch will always have a XIO instruction associated with it.

What happens if things are switched and you use a normally open stop switch with an XIO instruction or vice versa and normally closed start switch with an XIC instruction?

You get the same effect..............right?

Mark
 

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