PLC master in the making? from novice

hi guys, i have just signed up to this site after reading through it with much interest over the last few weeks.

i am as the thread title states, a novice in PLCs, what they can do and how they work, and i have been dropped with the dreaded traffic light task by my new employer!

a little bit of background info for you all, i am 25 and have recently completed 2 years of full time study in electrical installations and services at college, and wanted to take the next step up and further my learning; being rather academically minded. the next step was to take the HNC in engineering; which, after 3 years part time study will award me my foundation degree.
my new employer is a firm that specialise in designing, manufacturing and installing PLC systems across the globe, with the food industry being their main niche.

as i have already stated i have never touched a PLC system in my life, but have been left with a laptop, the RSlogix software (for Allen-Bradley), and a test PLC so i can carry out this accursed traffic light task, and no-one to show me the way.

many of you at this point will click away thinking i am asking for help on this program, i am not! i know that as a novice, every pro starts out at humble beginnings, and all i ask is how did you guys start off, did you find it as hard as me to do it all on your own? and are there any books or guides out there you'd absolutely swear by that have helped get you where you are today? are the guides advertised on this site for example, excellent reading for PLC engineers of all levels and abilities? i don't want to throw away money needlessly, as i have had to take a big pay cut to carve the path of a proper career, after spending the last few years in the employment doldrums.

please help!

many thanks in advance

Aaron

welcome to the forum you will find it full of useful knowledge.
we both seem to have a similar career direction, only 24 but I have already got my HND in elec and electronic engineering and can program AB and mitsi plcs at the moment I'm in a maintenance role but I am always working on plc projects and one day move into a project/plc engineer role hopefully within the company, anyway back to your question, Its easy for your traffic light program but it's you been able to know the necessary steps to use rslogix, so you don't know anything about the software? could you let us know what type of hardware you have to program (plc) and a great place to get info is the Rockwell automation website ( FYI Rockwell is Allen Bradley)

Here's a few links for you..

http://www.ronbeaufort.com/sample_lessons.htm

http://thelearningpit.com/lp/logixpro.html

http://forums.mrplc.com/index.php?autocom=downloads&showfile=156

http://www.plcdev.com/allen_bradleys_plc_programming_handbook

There is a good reason why the traffic light is so often assigned as an exercise to a novice PLC programmer. Everybody understands how it is supposed to work so you don't have to spend a lot of time reading and interpreting an operational specification. The only problem is that you really should spend the time creating an operational specification before you start writing any code. The ladder logic code to make it perform can be surprisingly complicated. Also, there are many variations you can add to it. Trying to add a variation to existing logic can be easy or hard depending on the amount of planning you do before you write the first rung of ladder logic.

Ha ha, the dreaded light test.... is it a simple two traffic light system they want or is it one for a crossroads, pedestrian buttons etc ?

Sit down with paper and pen and write down how you think it should work !! traffic light 1 is on green, traffic light 2 is on red etc etc... then you can start to work out the sequencing you need..........

P.s welcome to the forum

JV

Go out and watch real traffic lights is a good idea too.

Some of the best starter info is right here on this website. Mr Melores publications are good.

Dan Bentler

thanks for the replies guy, much appreciated, and cheers mickey for them links, i've added them to my favourites and starting reading through them!

some people (excepting leitmotif, robw53 and mickey) didn't read the full contents of my opening statement; i'm quite happy trying to figure out the traffic light system, and understand it's probably been asked a million times, so i have sat down and started working on the sequence etc

my question was (as a reminder):
how did you guys start off, did you find it as hard as me to do it all on your own? and are there any books or guides out there you'd absolutely swear by that have helped get you where you are today? are the guides advertised on this site for example, excellent reading for plc engineers of all levels and abilities? i don't want to throw away money needlessly, as i have had to take a big pay cut to carve the path of a proper career, after spending the last few years in the employment doldrums.

cheers!

Ok. If you're starting at ground-zero with no one-on-one support of any kind, the very first part of the learning curve is going to be kind of tough, but it can be done. One of the first things you will want to know is that programming a PLC is easy. There are only six parts.

1 - Assemble and wire up all the components you will use (PLC, Cables, power supply, I/O cards, pushbuttons, lights, etc).
2 - Acquire or make functional your programming device (PC with software, in your case)
3 - Establish communications between the PLC assembly and the programming device.
4 - Write the program
5 - Transfer the program from the programming device to the PLC (steps 4 and 5 are sometimes combined - this is online editing)
6 - Compile the program and put the PLC in run.

Now, with all that said, these are only the absolute, rock-bottom, steps required to program a PLC - there are also a bunch of really important aspects to learn before you are ready to create a real-world program for a real-world machine (planning, safety, technique, etc).

So, to start, I recommend the "Learn PLCS" link at the top of this forum. It's basic and covers the important steps.

Next, I would get (download) the hardware manuals for the PLC components you have. This will tell you how to wire them up so they are ready to program and use.

Next, get the programming manual for the software and focus on learning the basics of your programming software. Learn how to write one, single rung of logic on it. This will get you familiar enough with the software to take you to the next step.

Next, I would focus on establishing communication between the software and the PLC. Get the right cables and learn how to make them work. You may need stuff you don't already have now.

Finally, between your programming manual and hardware manual, figure out how to transfer the program from the programming device to the PLC and make the PLC "Run".

Once you have this, you are ready to learn how to program. Following Mickey's links will take you a long way.

Steve

that's more of the reply i was looking for, and very informative, thank you Steve. you've taken into account that i mentioned i'm at the bottom with little/no support.

looking at what you've put, i've managed to get the gist of some of the things mentioned, but as i didn't know where to begin it was all fragmented knowledge that i hadn't been able to refine to put to use. i'm not an idiot, i can learn but with a brand new subject that is alien to me i just need a nudge in the right direction. now i have a definitive order in which to get my information i can reassess my learning, so many thanks indeed!

any more thoughts are still greatly appreciated

Hello,

I don't know how much time you have, but I found it very useful to go through the entire Logixpro program from the start. Do the lessons provided with the simulator. By doing it that way, I was able to program the traffic light using the info I learned doing the lessons leading up to the traffic light.

Good luck...

Dave

my question was (as a reminder):
how did you guys start off, did you find it as hard as me to do it all on your own? and are there any books or guides out there you'd absolutely swear by that have helped get you where you are today? are the guides advertised on this site for example, excellent reading for plc engineers of all levels and abilities?

Hmmm how did I start out?
1. Decided I had to learn PLCs.
2. Bought a Siemens read the manual and started to teach myself.
3. After a short while I decided my instructor was completely incompetent and would likely zap or kill me.
4. So went to a Community College found myself a competent instructor AND found all kinds of free stuff to work with mostly AB 2000 era PLCs.

Dan Bentler

It would help if we knew which AB software you are attempting to use.

sorry aaron when i first replied i was doing it via iphone and i was unable to read your question whilst posting, well steve has pretty much explained the way to go about it, when i first started i spent a few hours on the software looking around it and looking at the manuals ready how to use RSLinx, and RSL500, once i was confident in how to upload and download i then went to one of our machines, (the only AB machine) and took the program out of it and also viewed online and watched what was going off, once back at the shop with the program then i looked at the program and went through the instructions to see how they were assigned usng the various data files (B3, T4, C5) etc, i didnt have the luxury then to have a plc to hook up and practice with which makes it so much easier then working offline and reading manuals, do you have a project to send to your PLC to have a play with? if not i can do you one for that processor and email it to you.

once you get your head around the basics then your ability will soon increase rapidly, i moved companys to a big canadian bakery, (Mapleleaf) and within 18 months id gone from been able to program and modify micrologix, to programming compact/controllogix plc's, ultra 3000 servo drives, RSview studio ME , Panelbuilder 32, RSnetworx (devicenet, ethernet)and ive done loads of projects which just keeps increasing your understanding and learns you new techniques to problems. but i have spent alot of hours just reading posts on here, reading manuals and looking at programs from machines at work, but that was in a maintenance role and not spending much time at work programming, im guessing you will be able to spend quite alot of time to go through it.

sorry if ive waffled on a bit, if you are ever struggling with something im only a phone call away and would be more than happy to go through anything with you.

as far as books are concerned i dont belive there to be any on AB as such as there is such, but you can learn without them, just find a topic you want to learn about, e.g. uploading/downloading and then go through the rockwell manuals and get your head round that and then have ago with your micrologix

hope this has helped if only alittle

Rob

On the subject of starting out, I was working with a company in the early eighties
which were agents for many different types of machines from different suppliers
and as an installation and commissioning technician I was expected to know how to set up machines. One of the suppliers started using Klockner Moeller PS 24 PLCs and sometimes Siemens S5110A and I just had to learn about them, on my own, no internet, no forums.
Both of these PLCs had dedicated programming hardware not even remotely related to a PC.
I then got to work with 5TI and PM550 PLCs from TI, which used a terminal called a VPU200 which at that time was high tech, it had a CRT and floppy disk drives.
Then I did a lot of work in the later 80's on Symax PLCs from Square D. Super machines.
Do any of you older guys on here remember any of the units above?