PLC master in the making? from novice

[robw53]

good call STL i actually thought he had already mentioned he had a micrologix lol

 

[KalleOlsen]

Do any of you older guys on here remember any of the units above?

S5110A (+ PG631) was mine debut also. I remember I had to set a certain marker (M0.0?) to perform a jump. Hardware timers. I don't miss those things at all.
After that it shone up with PG675 and 150S, 110SB, and then the U-series.

Kalle

 

[Liam Moran]

S5110A (+ PG631) was mine debut also. I remember I had to set a certain marker (M0.0?) to perform a jump. Hardware timers. I don't miss those things at all.
After that it shone up with PG675 and 150S, 110SB, and then the U-series.

Kalle

Ahhh Memories....:nodi:

 

[Clay B.]

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?

First PLC I got to program was a TI5. My dad gave it to me for Christmas.The company he worked for were changing them out for TI545s. I actually used a VPU200 a couple years back on a TI5 still running in a machine. That was a blast from the past.

As for the poster's question, the thing I try and hammer home to my guys, it is not about knowledge as it is how to think, Programing is telling a machine EXACTLY what you want it to do. Where knowledge is important is when you need to understand the hardware. That is what manuals are for.

Bit of advise. When you first read the manual be sitiing at your computer. Depending on the manual you will find terms you do not understand. Google is your friend.

If you are looking for do it yourself manuals I highly recomend the ones sold on this site. I have purchased them and given them to my guys and I can say they really helped.


Good luck, this engineering field is always looking for people to punish.

 

[chizzler]

my first experience was with a Omron c20 with hand held programmer.

 

[Lancie1]

...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.

Aaron, at least you don't have to figure out what equipment to buy and write purchase orders for it! You have a head start already! Welcome to PLCtalk.

The traffic light program is not cursed, but it has been around the block a few times. For some samples, look in the "Downloads" section, or do an on-site search for "Traffic Light".

EDIT: One of the most useful things I found while writing the traffic light program was a timing diagram (see attached picture). I made an X-Y chart (in Excel spreadsheet) with "Time in Seconds" on the X-axis, and On/Off on the Y-axis for each of the 6 lights in a typical traffic light. What you will see right away is which of the lights are ON at the same time. Also a timing diagram will help you figure out the ON times for each light and the total cycle time. With that, I was able to figure out the minimum number of timers needed to control 6 PLC outputs. Four timers is a good number for a beginner to use. Later you can use more advanced instructions and use only 1 timer.

 

[AndrewM]

Hi Rothman

I think the course I have just taken maybe of interest to you,
Its with a company called scantime(www.scantime.co.uk) they get you up to speed quite quickly on things like the traffic light project and they also make you think about the safety side frequently, its an online course so you can do it when you want and I found it reasonably priced for what you get.
The part1 maybe a bit basic for you as it goes over the maths and boolean etc. but could act as a refresher.

Regards Andrew

 

[L D[AR2P#0.0]]

My advice would be to steer clear of the traffc light problem until you have a thorough understanding of your system. I do this by taking simple tasks and then gradually complicating the implementation to take in more and more of the instruction set.

 

[Lancie1]

My advice would be to steer clear of the traffc light problem until you have a thorough understanding of your system.

What?

LD, I respect your opinions, but why is the Traffic Light not suitable for beginners?

If it is not, a lot of techincal school PLC instructors sure got it wrong. They like it because it has no external inputs, so a beginner does not have to know how to do wiring to program it; it only needs light outputs (which can simply be the indicators on the PLC); it is not too long that students get discouraged; it requires thinking about how a real-world device operates; requires converting those requirements to a program; and can be implemented in many different ways from simple to more complex.

What more could be desired for a beginner program?

 

[L D[AR2P#0.0]]

I see the traffic light task as a design exercise that will slow down the process of becoming familiar with the plc.
(Caveat: I have never ever done a traffic light task, what comes to my mind though is a real set of traffic lights and the associated sensors and decision processes involved to maximise traffic flow through a junction )

 

[Lancie1]

LD,

It could be a cultural difference. On a vacation trip to London, I loved the great subway and train system. You could go anywhere without a car, so traffic lights were not so important. Here, there are vast spaces with no trains, subways, or bus service. Every 16-year-old has to become familar with traffic lights and driving rules. If you ask the typical American what a green light means, they will say "go". In many other parts of the world they will say it means you have to wait for red to cross the street.

 

[leitmotif]

I think there are darn good reasons to argue doing the traffic light or not do it.

The main reason I can think of is one should have a good understanding of what happens if
two contacts each NC and one configured as normal open and other as
normal closed in PLC.

AND
two contacts each NO and one configured as normal open and other normal closed in PLC.
Each of four contacts are wired to a light bulb
Student prepares predictions
What lites lit wehn PLC turned on
What lites lite (or turn off) when appropriate button pushed

This exercise helped me understand this - which is why I sought out a qualified instructor. In my self teaching I energized PLC no inputs wired in and no loads connected. Had an output light and an output voltage. Fired my instructor (me) an found a qualified competent one.

Dan Bentler

 

[jude]

have to say when I started and they gave us the traffic light project drove me crazy for a while getting the timmers figured out but it certainly gave you an understanging of how they work

 

[bluebyu]

I agree with LD...

A long time ago, some co-workers gave me a general idea of what the plc is doing. They showed me how to use the TI VPU200. ("Video programming unit", Early 1980's Texas Instruments, 510, and 5TI. Some 510's are still running in the same plant today!)

I was able to take the spare VPU and a TI 510 (plc) home, the first thing I did was wire ONE input, and One output. I programmed the plc to turn the output on when the input came on. Baby steps were correct for me. If I had to do an entire traffic light program as a first step, I may of failed.

From my first success I added more code, timer to flash the output, timer for how long the output stays off etc.

If you go down the self taught road, eventually you will write some code and the PLC will not work as you intended. "Be prepare to mutter under your breath that this plc is a "defective ***** PLC" (I assume you can guess that it is you that is wrong, not the plc)

I look back at my PLC on the job training and know that after turning some outputs on and off at home, a professional basic PLC training class would of been a a wonderful investment.

Any maintenance techs at work whom deal with PLC's are sent off to our local Omron Distributor for the basic training.

Good luck

 

[Lancie1]

I look back at my PLC on the job training and know that after turning some outputs on and off at home, a professional basic PLC training class would of been a a wonderful investment.

Yes, but does it make sense to pay for PLC training if it is really not what you want to be doing the rest of your life? How do you know that if you don't first get your hands on a program and try it out? It is the old chicken-and-egg question: which should come first - experience, or training that allows you to get the experience?

A PLC Simulator prgram is a good solution. You can write programs, try them out, and get an idea about if you want to keep doing it, without spending a lot of money or time.

The main ingredient for success, as in any other endeavor, is the burning desire to do it. All else will come, if you want it bad enough.