No sweat, just nit-picking !
CompactLogix - Linearization instruction . Trying to understand . Any thoughts ?
- Thread starter Rob S.
- Start date
No sweat, just nit-picking !
For this "simple" equation sure.
Whether or not if "people don't have it, and some don't allow it" is irrelevant to value of ST when it comes to performing math. I'll avoid the topic of management ignorance and how people let it dictate code.
But wouldn't a "ladder" of CPT instructions look just the same ? The expressions would be the same, but would be displayed in instruction "boxes" instead of being lines of STL,
Probably best to....hehe...
Say the math is more complex. You have a tank with a cone shaped bottom (cone + cylinder). Has a pressure sensor 1/4 the way up on the cone. Customer wants to see volume in that tank as bbl (barrels, think beer fermentation tanks!) and account for specific gravity. Customer supplies drawing geometry of the tank...
Oh, and they also want the level indicator on the HMI screen to fill as close to physical filling of the tank, as they do have separate cooling zones on the cone and the upper part of the tank, so there is value in seeing the fill level w/respect to the temperature probe locations.
Not sure about you but when working this out on paper, my work looks more like ST than it does "boxes".
I spent best part of 20 years working on Allen-Bradley systems in Breweries - we did all of that in Ladder, we had to before Logix5000 arrived on the scene, and most of our customers wanted it in Ladder even though STL and FBD were then available, because that's what there maintenance engineers were familiar with.
Let's face it, it's only a different representation of the same maths. We are arguing (too strong, discussing) presentation, not functionality.
Presentation is the entire reason I suggested ST. Its a great example why you might want to use one language over another, and in the OP's case probably have been obvious to what it was doing. Math - universal language unless it isn't..
Since an AOI can be written in ST yet called in LAD, I'd say it completely conforms to any LAD requirements any end user would have. Native instruction or Add-on instruction, if I call them in LAD, it's a LAD program
That's great - if you can get away with it.....
You just might if you prevent the end-user from actually viewing the AOI code, but not all clients will accept ANY source-code protection applied, even if they didn't pay for the development of the AOI or routine.
There's still that pesky icon in the AOI program folder that can give it away though.
When clients' specifications say "ALL PLC CODE MUST BE WRITTEN IN LADDER LANGUAGE" in Bold AND Underlined, it can be hard, or even impossible, to get away with anything underhand. The guys who attended FAT were no chumps, and expected the "standards" they imposed to be followed to the letter.
Let's leave it at that - sometimes (often) you have no choice.....
daba, out of curiosity do you not agree that my ST example is good compliment to the discussion of the original topic? From a pure PLC coding perspective excluding any outside influence?
That is all I was presenting.
I had my disclaimer:
That is all I was presenting.
I had my disclaimer:
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