Question about PLC education 2

[MazukFarnas]

I am an electrical student (2-year degree) who is nearing graduation and I have already had some PLC classes, but I feel like they just scratched the surface and I would like to further my understanding and improve my ability to work with PLCs. I find it very hard to find programs & curriculums that would adequately prepare me for a job in this field (my dream would be to one day be a Controls Engineer).

I recently had the chance to speak to someone who is an electrical supervisor working for a large company which is almost entirely automated. He deals with PLCs on an almost daily basis. I asked him how he was able to gain his PLC knowledge and he told me that he basically just bought some PLC equipment and software and set up a station at his house and messed around with them until he felt comfortable.

 

[thebard3]

That's how I learned.

Brad Waybright

It's all okay as long as it's okay.

 

[itsmoked]

That's the best way.

Pick up a CLICK CPU from Automation Direct and a 24VDC power supply. Pick an Analog Ethernet PLC. Download the free development software and have at it.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[controlsdude]

If you have some distributors of plc equipment in your hometown. Just ask if they have a lab and could you come and try to self teach yourself at their equipment. Most would let you do this at their facility. Since they see you as a future customer and would make good business sense. Also, most distributors will let you borrow a test stand (plc in a suitcase) to let you train on it.

Just call and ask.

 

[waross]

I got pushed off of the board into the deep end, twice.
Years ago I developed and taught a course called "Industrial Controls" for electricians.
Several years later I was asked to teach a course in industrial controls for electricians at a local college.
No problem I thought.
I wrote the course, didn't I?
Well in the interval PLCs had come on the market and the Industrial Controls Course now included PLCs.
The lab had two PLCs with completely different programming methods.
I had a three day lead on the class to get up to speed.
We learned a lot together on that one.
Some years later I was tasked with rebuilding a control panel at a refinery after a small fire impinged on the back of it and melted everything that wasn't copper or steel.
There were gaps where die cast fitting used to be.
I suggested to my supervisor that we consider replacing the $2000 worth of destroyed relays with a PLC.
I got the OK to price a PLC and the price was good.
I bought a brand that I was familiar with, I thought.
Whoops, new model, new programming method.
This one used Boolean Algebra instead of ladder logic
Fortunately I had some experience hard wiring Boolean in the days before PLCs.
Programming is a lot easier than hard wiring.
I guess that this self training method may be a little hard to duplicate.
BUT
A lot of advanced learning is done on the job, under pressure.
Good marks will demonstrate basic knowledge and an ability to learn and help you get a job where your PLC education can continue.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[jraef]

The problem with PLCs and schools is one of having to make decisions and investments, in an ever-changing environment filled with competitors that have sometimes very different design philosophies and approaches to programming. So if a school invests in Siemens PLCs and software for their class program, their students get out into the world and know how to program Siemens PLCs, but can get lost on A-B systems, and vice versa. In the early days, the larger players provided free equipment to schools in order to promote their particular brand / design strategy, but those days are gone now.

If you look at the preponderance of evidence when it comes to getting a job in the field, North America is primarily A-B based and everywhere else is primarily Siemens based. We don't know where you are, but you do (presumably?). So if you are not in North America, I would look for any training classes offered by Siemens in your area in order to maximize your chances of being employable. If in North America, do the same with Rockwell / Allen-Bradley courses.

In both cases if you have to start off on your own without organized classes, Siemens and A-B offer small inexpensive (around $100 US) PLCs that have free (or cheap) programming software as "entry level" systems; that's a good way to get started. The software is not the same as in higher level systems, but is similar enough that you can understand the more complex versions later.

Rockwell Micro800 PLCs, software (Connected Components Workbench) is free.

Siemens LOGO! PLC, software (LOGO! Soft Comfort) is cheap.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[tygerdawg]

jraef makes a good point.

Part of my current life is teaching "automation" at the University level. I entered into an organization that went down the A-B rabbit hole due to the insistence of Advisory Board member with a strong personality who wanted graduates that knew RSLogix, CompactLogix, et al. I had spent some decades as a shop-floor automation engineer and came to loathe Allen-Bradley equipment and software. Powerful, robust, fast, wonderfully supported, pervasive, shockingly expensive, and a gigantic pain in the YouKnowWhat for small tasks and daily machine support. My automation requirements were definitely NOT high-performance and I quickly became a fan of the AutomationDirect products for cost, ease of use, and ease of replacement.

Faculty leadership reacted to the Advisory Board's demand and resulted in a $250K expense for a bunch of NEMA cabinets with CompactLogix PLC CPUs, a small assortment of I/O modules, and some switches, sensors, and lights. A separate touchscreen interface was included. It was hard to do any interactive wiring, the A-B ladder logic programming software is (IMHO) unnecessarily complex for I/O point addressing, and the documentation is massively extensive and heavy to read. Students generally hated the entire affair, even to the point of sabotaging the trainers. We spent an inordinate amount of time learning the A-B software interface rather than programming skills and gaining experience on automation functions and techniques.

We were also burdened by the annual root canal of getting all of our Rockwell licenses deployed, re-imaged to all lab PCs, yadda yadda yadda. We suffered through the planned obsolesce problem of newer software revisions not backward compatible with hardware. Gawd, what a mess. So I took the disruptive innovative approach of challenging the status quo. I stated that it is more important to educate future engineers in fundamentals of Relay Ladder Logic programming and Human Machine Interface programming than it is to be a job skills training center for Allen-Bradley equipment and software. I endured the A-B distributor's spiel about "value proposition" and finally told him there is no value to A-B products if the students aren't learning anything from it and the cost (piece part and deployment cost) is excessive.

The overhaul of the teaching game included my own design of an MDF training board with SPDT, DPDT relays, timer relays, beaucoups of terminal blocks, power supply with fuse blocks and power distribution, push buttons and switches and lights. I chose for the hardware an IDEC SmartAXIS Touch mini PLC with integrated color touchscreen (we got big Academic discounts). We added some cheap digital and analog sensors and used student Senior Projects to design daughter boards with pneumatic and electric actuators for real-life device simulations. The students are put through a sequence of non-PLC fundamental relay logic control and simple wiring skills and diagnostics. They then progress to fundamental RLL programming and HMI programming and integration. The philosophy is to teach the fundamentals so that after graduation they can learn A-B or Siemens or OMRON or Mitsu programming packages as needed because they will understand the fundamentals which are translatable to any specific vendor package. We also use these powerful little boogers to do PID loop programming of level control loops, thus teaching fundamentals of Process Automation.

It's been very successful and costs a heck of a lot less than the A-B expense. We are looking into the next generation of trainer board using Unitronics combo PLC+HMI units.

TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering

http://www.bluetechnik.com

 

[wde0665]

Suggest that whatever you program or build, leave a trail of bread crumbs so that others can easily understand what's going on. Leave plenty of comments in the logic to explain the intent of blocks of code. Never make anything more complicated than it needs to be.
What may be technically brilliant and efficient at the time could be insufferably painful for you after a few years have passed, for the next guy following, or for the shift craftsman called over to figure out where the machine lost its do-right, especially in the middle of the night when one already isn't firing on all eight.
The challenge I've experienced with external training resources is too much news. The majority of systems that new guys will be working on are already up and running - no need to go into details on how to build a system, want more towards things like how to access the program, add an I/O card, expand data table allocations, tricks for searching, etc. - the real world stuff rather than the theory.
Then, as mentioned previously, best to just get in there and do it - with strong caution advised to save a copy before changing anything. If you aren't bet-your-life sure where you're going, make doggone sure you can get it back to where you started.

 

[thebard3]

I can't really say I disagree with anything you guys have said, but my opinion differs somewhat.
Firstly, Every day I live the pain of the obsolescence that all equipment experiences. Not just PLCs but drives, servos, instrumentation, networks and just about anything else. I remember using DOS and Windows 3.1, and where I loathed losing XP and having to learn Windows 7, older software and hardware just doesn't support the increased functionality and speed of the new (and better) stuff. I'm and AB guy and have been for 30 years. There is no way the older stuff can support the level of automation we use today. Even stuff that's 10 years old is taxed of resources. I recently did work for a system integrator and found all of our customers who didn't use AB complained about how expensive and hard the AB stuff is to use. I personally find it to be just the same, only different.
Second, as for the suggestion to make things easy for others to follow, my employer pays me to create the best logic I can to operate our equipment. My objectives are to make the system reliable, safe, and easy for operators to use. If your employer were concerned about others' abilities to follow your work, then they should make the investment necessary to have people with more than a rudimentary understanding of PLCs and other industrial control equipment in the role of maintaining it. Nobody should be getting into the logic and changing things if they don't know how it works.
Third, If I get laid off and they are left in the lurch as a result, well then that's just bully for them.

Brad Waybright

It's all okay as long as it's okay.

 

[buzzp]

All good comments. Learning ladder logic is the easy part. Learning all the nuances with different manufacturer's is the hard part...communication setup, programming, troubleshooting, etc. All the stuff you think should be on the front page, is not. In fact, it is often buried in more than one document, if it is documented at all. I have used Rockwell, Siemens and GE. GE is by far the easiest to learn but is certainly not the most common. Rockwell is selling a name and you pay a little extra for this. However, the lack of documentation of what should be fairly straight forward tasks, is hard to find. If you are using FactoryTalk for HMI's, this is even worse than programming a PLC. For HMI's, Ignition is the only way to go and will work with any PLC I have come across (Ethernet or Modbus). Don't expect much support from Rockwell direct without a support contract. Even their training DVD's are overly complicated as far as setting up a license server.
You can get training on PLC's almost anywhere once you decide on what brand you want to learn on. There is also a lot available on the internet, without paying a dime. However, don't expect to learn one manufacturer and roll this over into others, except for the bulk of the ladder logic and FBD's (still have differences here but small). Yes, Rockwell and Siemens are by far the most popular, not necessarily the best.
End of life is an issue for all the manufacturer's I mentioned. However, I think firmware compatibility with programming software is an issue with Rockwell than any other manufacturer, especially with HMI's. I haven't used many Siemens or GE HMI's so I don't know if this such a big issue with them.
...oh, comments, narratives, and any other documentation is greatly appreciated. Not only for your employer but for you. We have PLC's and HMI's all over the place here and I inherited it from another engineer that left the company. His programming style was way different than mine and there are absolutely no comments in the logic, no narratives, no nothing. When your dealing with large programs and many routines, it makes life very difficult for the next guy and maybe you as well, depending on how much you get bounced around. In my position, I can easily forget how I did something a year later. When you are called in the middle of the night for troubleshooting and have to look at undocumented logic, it always takes more time than it would if it were documented, even if you wrote it.

 

[PNachtwey]

I cringe when I hear about students taking courses on PLCs. There are better things to learn while you are piling up debt. Differential equations, numerical analysis, statistics, physics, thermodynamics, real control theory, boolean algebra, state machines, motion control, programming techniques, and algorithms, etc.

The PLC is just a tool and they are cheap enough where you can buy one and automate your train set, automate brewing beer or some other project on your own. Ditto, purchasing a cheap Automation Direct PLC and learn on your own. I also know that an employer would be more interested in what you did on your own that what you did in a class. It shows a desire and interest as oppose to just getting a grade.

PLCs are just tools. They change with time. What you want to learn in college is what I call "forever knowledge". That is knowledge that will not become obsolete like PLCs do.


Peter Nachtwey
Delta Computer Systems

http://www.deltamotion.com

http://forum.deltamotion.com/