PLC Programming.... or what... cars & motorcycles?

OT Post

Terry,

I hear the weather is nice up there right now but how cold is the beer? I’m headed your way Monday and Tuesday of next week.

[font=&quot]Bob O.

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Beer is plenty cold. Been hotter than heck around here lately. Add in the fact that the factory is usually 5 degree warmer than outside air and its even worse.

There is an art to programming, I see the artistry in the simple elegance of a well written program, almost anyone can slap a few contacts and coils into some ladder logic but good PLC programs rise above this. And I listen to all the complaints about logic faults and I can say that a PLC program written by true master craftsman (I don't put myself in this category) won't have any. I have seen very few really well written PLC programs but the ones I have seen jump off the page at you.

Better than *** ! don't care what anyone says , it is a true art , and when it is up together , it is a thing of great beauty and joy to behold , I'm not talking about you lashing a coil up with a timer and an input , but something that is really smart to look at , works ,and is easy to extend should the need arise . People say you can write software without the processor , I disagree upto about 97% , you can , and have it working before it goes near a PLC .
True Art.

Terry,

Very interesting thread. Programming is both an art and a skill. I have had many discussions with my programmer. He will tell me, that there are many ways to program an application. Where it becomes both an art and a skill, is developing the most efficient solution.

When we do programming for a new OEM application, I will usually help to verify the program with my programmer. It is an extremely sweet feeling when an application is completed and works just as the customer wanted...and I'm not even the programmer.

Sort of related.

We got a call from a customer ranting at us that our hardware was defective. Said the controller was working for three weeks without a problem and all of a sudden multiple alarms were tripping. We had been out there once before, made some modifications to our analog board because they were using grounded RTDs, Ground potential ranged from 100 - 250 mV with 400 mV spikes.

So, he rants and raves about our product and that if he has to send someone to fix our problem...he was going to bill us for it.

Sure enough the customer program was missing several compare statements that caused the controller to trip on multiple alarm conditions because it was comparing all these set points with one compare.

We had another customer who was concerned because the program that was developed for him wasn't working properly...it kept resetting the controller. This controller had a special operating system for two high speed counters, that require a specific relay to turn on the input and activate the value in a specific TC register. It turns out that he has wired his two encoders that generate no more than 20 Hz to different outputs, which is acceptable for our inputs, but is still using the relays in the program for something else. In addition, internal relays 1 & 2 are special relays that are used to monitor the condition of the PLC...they are using those relays in the logic of the program. We told them to make certain changes. For the last three days, everything is working better than he could expect.

To the defense of the programmer, he was new to our products. A learning curve with everything....that is the skill part.

In writing this...the skill is knowing what to do with the product you are working with...the art is the program...a creation from someone's idea. Making an idea a reality from a concept is certainly an art.

There are many programmers out there that have the skill to program...but not all of them have the creativity.

And on a final note...there are countless times we will get product back because the customer tells us the controller is bad...and sure enough, it isn't the controller, but something else in their panel.

God Bless,

I still find it hard to understand why people believe that writing a PLC program well is art. A well written program occurs when the requirements of the system to be controlled are fully understood and the capabilities of the PLC are known. A highly skilled engineer will have a good understanding of the requirements even if the those requirements have not been explicitly written in a specification document. A less skilled engineer will need a good functional requirements specification to write a good PLC program. A newbie will need to be spoon-fed. There are no secrets to writing PLC programs, just make sure you understand the process being controlled and read the PLC manuals.

To those that find PLC programs aesthetically pleasing, I suggest taking a vacation.

In fact, they agree, those that identify the existing diversity of information, must be converted in perfect way into a software.

Ushidayo, you before post. accurate, subject.Because it needs to improve.

Tom Jenkins

When I was a young rookie engineer I thought one of the neat things about engineering was that it had right answers and wrong answers and was a discipline with structured approaches to problems.

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Then, to produce with art it must have as requisite to perceive problems.He considers can be learned as one disciplines, as experience not only acquired?

Monkeyhead

...startup sequence was beginning while the shutdown sequence was also happening resulting in a giant mess

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Lithe manuals, warning complementary instrutions need interlook. + year discovery it... is long loss.

No secrets ? how does this place do so well then ? I won't ask to see any examples of your software , as you clearly don't enjoy writing it , and don't see anything remotely enjoyable about a job well done !
Any born idiot can get something out of a PLC with a combination of manuals and luck - he might do a nice job , but more likely he will make a hash of it - so the lights come on , there is no thought to safety or error tracking , or debugability of the process , no decent block and rung and I/O comments , impossible to extend it without re-writing it - its OK though , it works .

The good software engineer can walk around the process and understand 95% of it before talking to the process people for a spec , he generally gives more suggestions and refinements than the end user , and he produces a professional tailored job that can be understood by others , with no relics of old code and other rubbish left around .
I like to think that when a future programmer looks at my software for whatever reason , he doesn't fall over laughing or go white. I'll post a comment for you , this is the way it should be :-

"I did however go through the Overview document and the structured block samples and I can say that it looks like real good work and I suspect that this person is a very thorough programmer."

Might not mean much to you - but it makes this guy feel that it is worthwhile - as you would say " not an art ? balderdash" !!

ushidayo said:

To those that find PLC programs aesthetically pleasing, I suggest taking a vacation.

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If I only had more vacation time left . . . Oh well, back to writing some more "pretty" code . . .


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Actually, I can see both sides of this issue. I think the "art" comes in seeing the bigger "picture" about what the real machine specifications should be.

All code that completely meets the functional specs is OK (though not necessarily "art").

Writing code that is structured in such a way that potential future enhancements are intuitive and easy to make is (to me anyhow) the "art" of writing a good program.

The ability to structure the data and code in such a way that troubleshooting is intuitive and easy (and even self-diagnosing) is also an "art".


Marc

ushidayo said:

A highly skilled engineer will have a good understanding of the requirements even if the those requirements have not been explicitly written in a specification document.

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And that, my friend, is an art.

Is Dandrade for or against the motion ?

Unregistered said:

The good software engineer can walk around the process and understand 95% of it before talking to the process people for a spec , he generally gives more suggestions and refinements than the end user , and he produces a professional tailored job that can be understood by others , with no relics of old code and other rubbish left around.

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Nicely summed up there....

Oh good, I think I've rattled a few egos.

From my experience, bad PLC programs arise when the programmer hasn't understood the requirements. These misunderstandings aren't found until testing and commissioning. At this point in a project, the deadline is looming and often the budget is starting to get stretched. The program bugs get fixed (one hopes) but the structure of the program starts to get out of shape because there is no time for a tidy correction. Maybe during commissioning the customer asks for changes, more corrections and loss of structure. You get the picture.

The good software engineer can walk around the process and understand 95% of it before talking to the process people for a spec

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Not if it hasn't been built yet. But I get your meaning, and I stated the same previously.

I won't ask to see any examples of your software , as you clearly don't enjoy writing it , and don't see anything remotely enjoyable about a job well done !

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Actually I find writing software a cathartic pursuit (emotionally, not laxative) and good stress relief. I gave up on showing off my work to others shortly after completing potty training. If I have offended or belittled anyone, perhaps you should ignore my posts.

Keep up the good work dear fellows, I know you do a great job really.

Before bed, I'll leave you with one thought;

The japanese artist Taro said "art is bang!"

Your obviously in software at the bottom end then if you get my drift .
Ego ? not at all , just pretty good at what I do , and quite like praise when due ( though far from essential , as I know the job is well done , which is enough in itself )
I'm generally involved in the design stage , rather than the laki stage , so possibly have more input and therefore enjoyment than you .
Did you give up on showing off ? or perhaps there was nothing to write home about , rather something for your little potty.

And before your bed :-

As the Mayor of Hiroshima said:-

" What the f**king hell was th..."