# Homework question.



## AXG89 (Sep 24, 2017)

So I'm in this industrial motor controls class. Right now we are on the programmable controllers part of the class. There's a question in the homework that I can't seem to find an answer for in the book:

"In a PC controlled system, can an output device like a solenoid be turned on using the programing device (programming keypad)?"

Can someone help with that please cause I've read this section of the chapter over and over and I can't find a definate answer.

Thanks in advance guys.


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## telsa (May 22, 2015)

Go ahead, get it wrong.

There's no shame in that.

&&&

No instructor wants his students 'solving' homework via the Internet forums.

BTW, if you're getting even 90% correct -- you're FLYING.

STOP trying to get EVERYTHING perfect.

Trust me, the 'system' HATES 'perfect' students. 

Bosses don't want subordinates that know more than they do... etc.

If it's baffling you -- it's baffling everyone else. Stay in the crowd.

You'll end up with a very high score -- and fly through life.


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## Mr.Awesome (Nov 27, 2015)

My only PLC experience is the brief introduction we got in school but I want to take a crack at this...
I find your question vague.
I want to say yes because the whole point of the programming pad is to tell the microprocessor to control the output devices.
I also want to say no, you cannot somehow plug the pad into the solenoid itself to turn it on as the solenoid is wired into a set of contacts controlled by the microprocessor.


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## JRaef (Mar 23, 2009)

AXG89 said:


> So I'm in this industrial motor controls class. Right now we are on the programmable controllers part of the class. There's a question in the homework that I can't seem to find an answer for in the book:
> 
> "In a *PC* controlled system, can an output device like a solenoid be turned on using the programing device (programming keypad)?"
> 
> ...


Does it actually say "PC", or "P*L*C"?



Mr.Awesome said:


> My only PLC experience is the brief introduction we got in school but I want to take a crack at this...
> I find your question vague.
> I want to say yes because the whole point of the programming pad is to tell the microprocessor to control the output devices.
> I also want to say no, you cannot somehow plug the pad into the solenoid itself to turn it on as the solenoid is wired into a set of contacts controlled by the microprocessor.


I agree, in addition to the ambiguous use of "PC" vs "PLC" (if that's exact), the wording of the question is very poor, or it's a "trick" question designed to trip up people who will otherwise just guess at things. Because you're right, the only CORRECT answer is another question, such as "Do you mean DIRECTLY by the keypad, or via the normal channels of how a controller functions?" 

Was this text written in 1985? Because almost nobody uses "Programmers" any more, they use computers and software. And if they DID mean a "PC" as in a computer being used as a programming tool, then this still leaves a LOT of unanswered questions, because SOME PLCs allow on-line forcing of I/O, some do not. So CONTEXT is everything.

Such is the trouble with "generic" PLC training courses; there is no such thing as a "generic" PLC! They are all different, program differently, function differently etc..


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## AXG89 (Sep 24, 2017)

JRaef said:


> Does it actually say "PC", or "P*L*C"?
> 
> 
> I agree, in addition to the ambiguous use of "PC" vs "PLC" (if that's exact), the wording of the question is very poor, or it's a "trick" question designed to trip up people who will otherwise just guess at things. Because you're right, the only CORRECT answer is another question, such as "Do you mean DIRECTLY by the keypad, or via the normal channels of how a controller functions?"
> ...


But it's not a "generic PLC coure" it's more of a "generic industrial motor controls" class so it pretty much covers the basics of all the different aspects of industrial motor controls. It is a pre-requisite for the PLC classes which are Allen Bradley focused. They have Micrologix, SLC, CtrlLogix, PanelViews HMIS, etc. In the lab that we will be training with. 

Yeah the book for this class has one or two vague, poorly worded and puntuated question per chapter( Maybe even misspelled words included). But its still filled with a lot of useful info. The book is "Electrical Motor Controls For integrated Systems 5th Edition" By ATP. It uses different manufactures as examples but it seems like it leans more toward Rockwell Automation. Like for example on the VFDs chapter it uses Powerflex parameter as the examples.


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## tates1882 (Sep 3, 2010)

My vote is no.


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## sparkiez (Aug 1, 2015)

You need to take this to your instructor and challenge the question if you typed it up correctly. A "PC controlled system" would not likely use a programming keypad. We can't answer the question, or give an explanation because it is a poor question.


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## MechanicalDVR (Dec 29, 2007)

I'm not sure what they mean by programming keypad. 

Some systems use a plug in module that has limited functions (such as checking the state of a solenoid) and you'd need an actual laptop to operate parts of the system independently or make changes and set parameters of the system.


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## AXG89 (Sep 24, 2017)

MechanicalDVR said:


> I'm not sure what they mean by programming keypad.
> 
> Some systems use a plug in module that has limited functions (such as checking the state of a solenoid) and you'd need an actual laptop to operate parts of the system independently or make changes and set parameters of the system.


Yeah I'm confused because according to the text on the book it seems like its leaning towards a no. But when I worked on wind turbines we had these kk electronics hand controllers that you could access the I/Os and manually force the outputs.


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## MechanicalDVR (Dec 29, 2007)

AXG89 said:


> Yeah I'm confused because according to the text on the book it seems like its leaning towards a no. But when I worked on wind turbines we had these kk electronics hand controllers that you could access the I/Os and manually force the outputs.


I've worked on many control systems and not all of the portable key pads have all the functions of a laptop, some settings are only viewable.


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## splatz (May 23, 2015)

Just IMO that KK keyboard or something like that is a specialty HMI not a programming keypad. 

I think it's a typo in the OP, should say PLC not PC, and the answer is simple no. In general the programming keypad is the pre-laptop way to edit the program, not directly manipulate I/O. 

I could be wrong or there could be exceptions to that, I have no experience with the programming keypads. I have worked places where they were still in use, but never used them myself.


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## AXG89 (Sep 24, 2017)

splatz said:


> Just IMO that KK keyboard or something like that is a specialty HMI not a programming keypad.
> 
> I think it's a typo in the OP, should say PLC not PC, and the answer is simple no. In general the programming keypad is the pre-laptop way to edit the program, not directly manipulate I/O.
> 
> I could be wrong or there could be exceptions to that, I have no experience with the programming keypads. I have worked places where they were still in use, but never used them myself.


I already answered the question with a "No" and turned the homework in. But heres a pic of the book and the page with the question in it. Its #6. It wasn't a typo, at least from my part it wasn't. This book has a couple of typos and mistakes in it that I have noticed. Maybe this is one of them.


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## Mr.Awesome (Nov 27, 2015)

I think you should ultimately refer back to telsa's initial post, this one question won't make or break your grade. But the debate here gives insight from others and isn't a bad thing.


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## telsa (May 22, 2015)

In life you must sweat the right things.

Fouled up, crossed up queries in an instructional text -- are not to be sweated.

In such situations, a 90% hit rate is the same -- even better than -- a 100% rate.

Trust me on this. I speak from cruel experience.

1) No way did your instructor ever hit 100%... nor anyone else before the Internet.

2) So, you're establishing that you're -- de facto -- a cheat -- yes using Internet forums is deemed cheating in the eyes of the 'system.' You're presenting the collective knowledge of Master Electricians as being that of your own. That's exactly what you're doing.

3) In very short order, this is picked up by your instructor. It will not endear you to him. The speed at which this is perceived will astound you.

4) When it comes time to put your foot to the pedal, the Internet cheat squad will be wholly unavailable. The 'system' will harshly discount everything you've ever submitted. 

5) You are miles ahead to stay in the pack -- near the front -- but never, ever, ever, do you want to be the fella out there with 100% scores. There is absolutely NO pay off. 

This is something that a young man does not perceive. He's been goaded his entire life to obtain higher scores -- on this or that. 

It's the Big Lie.

Humanity is a social animal. Humanity is insanely, irrationally, jealous of a perfect performer.

The 'crowd' will hate you. That crowd includes your instructors, and just about everyone you meet.

Especially your employers, your foremen, etc.

The IDEAL position is that of a 90% guy -- who could get even better with the assistance of a mentor.

Which is what all of your future superiors self-conceive themselves to be.

The A -- guy ends up sweeping the board -- in the larger game of life.

Trump is a classic A -- guy. Most every CEO of the Fortune 500 was an A -- student.

The primary reason they made it Big was because they had a mentor.

Perfect students rarely ever obtain a mentor. 

No-one wants to associate with a smarty-pants that makes themselves look dumb by comparison.

If you can take this wisdom to heart, the world will be your oyster.


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## Rora (Jan 31, 2017)

AXG89 said:


> So I'm in this industrial motor controls class. Right now we are on the programmable controllers part of the class. There's a question in the homework that I can't seem to find an answer for in the book:
> 
> "In a PC controlled system, can an output device like a solenoid be turned on using the programing device (programming keypad)?"
> 
> ...


Are output devices like solenoids turned on by logic-driven devices such as PLCs, even PCs? Technically, no, they're turned on by a discreet output channel, but would that channel be activated without a logic device telling it to do so? Semantics and therefore a poorly worded question.

I'm gonna assume that they're asking whether a programming device can force a D.O. state, and that'd depend entirely on the specific system. You can absolutely force output states most PLC programming software, but we're talking a keypad and a simpler system, perhaps it's not capable of that.

You'd probably have to read the text again and see whether forcing output states is mentioned as a possibility for the hypothetical software.


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## joebanana (Dec 21, 2010)

Look up the term "force" in the index.


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## MDShunk (Jan 7, 2007)

During my absence I briefly taught PLC classes at night to mechatronics students. It was frustrating as hell for me because the curriculum was, in my opinion, outdated and doesn't match how systems are used and installed in today's world. Reading that question and having todays PLC's in mind, my answer would be "absolutely". In today's world, I can log in from anywhere on planet earth and force the state of anything in a whole factory. What answer does the test author want? I have no flipping idea, but it might be a 'no' based on some outdated text in the book.


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## indel99 (Mar 5, 2018)

"In a PC controlled system, can an output device like a solenoid be turned on using the programing device (programming keypad)?"

First, a semantic problem, you dont' turn on a solenoid, you energize it! What the solenoid is doing after that (after being energized) it is the action for what the device (including the solenoid) is designed and built for (e.g. NO or NC contacts, opening a valve, energizing by contacts other devices...etc).
One of the main diferences between a PC and a PLC is that for PC, the main input source is the keypad. A PLC is a computer with specific modules for input, output, communications... You cannot actuate a solenoid with a PC, unless you have an interface board which would take instructions from the program and drive power components (power transistors, thyristors, triacs, relays) that eventualy drive (energize) a solenoid. On a PLC which is equiped with the right modules capable to interface for all kind of inputs and outputs, there is the possibility to create short programs to do just a simple command as energizing a solenoid. 
So, the answer to that not very well formulated test question is YES, but....see the observations above.


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