Guys Plz Help me out with this ladder Program.

sanilbalakrishnan · Feb 16, 2012

Code:

When Switch S1 Pressed L1 should be [B][COLOR=Red]OFF[/COLOR][/B] 
                       L2 & L3 should be [COLOR=DarkGreen][B]ON[/B][/COLOR]

When Switch S2 pressed L2 should be [COLOR=Red][B]OFF[/B][/COLOR]
                       L1 & L3 Should be [COLOR=DarkGreen][B]ON[/B][/COLOR]

When Switch S3 pressed L3 should be [COLOR=Red][B]OFF[/B][/COLOR]
                       L1 & L2 should be [COLOR=DarkGreen][B]ON[/B][/COLOR]

Guys Plz help me out drawing me a ladder program for the above question,

much appreciated...

shooter · Feb 16, 2012

S1 andnot S2 andnot S3 coil L2
S1 andnot S2 andnot S3 coil L3
S2 andnot S1 andnot S3 coil L1
S2 andnot S1 andnot S3 coil L3
S3 andnot S1 andnot S2 coil L1
S3 andnot S1 andnot S2 coil L1

iant · Feb 16, 2012

NON RUDE JUNOIRS - DO's & DONT'S

vikas1947 · Feb 18, 2012

ans

this was the basic 1

iant · Feb 18, 2012

vikas1947 said:
this was the basic 1

Of course it was Vikas1947

Now that you have given the OP the answer he will not try to learn.

Well done keep doing every ones homework.

Better still start your own forum "Homework and Assignments done for free"
Plagiarism - freely in use

Then we will be still answering these guys questions and doing their job for them while they get paid for it.

vikas1947 · Feb 18, 2012

shooter has done this before i only converted it into ladder

vikas1947 · Feb 18, 2012

iant said:
NON RUDE JUNOIRS - DO's & DONT'S

sorry i didn't checked ur linked

iant · Feb 18, 2012

the OP had posted a second request so I only copied the same link on this one

we are in the beginning of the new student year
so back to the same questions as usual.
I have the link stored and will post it frequently.

iant · Feb 18, 2012

vikas1947 said:
shooter has done this before i only converted it into ladder

the reason SHooter did not draw it in ladder is so the OP would do it himself

ydtech · Feb 18, 2012

What happens when no switch is pressed? All off or all on?

iant · Feb 18, 2012

ydtech said:
What happens when no switch is pressed? All off or all on?

I think they are supposed to flash and blow smoke

daba · Feb 18, 2012

ydtech said:
What happens when no switch is pressed? All off or all on?

ydtech has raised a good point.

All too often I have seen test and exam questions, homework assignments, course material, clients specifications, functional specifications, et al, that have this "incompleteness" or "ambiguity".

When I saw the original "specification", I turned it on it's head, and decided that a simple solution would be for all lamps to be on initially, and that S1 turns off L1, S2 turns off L2, and S3 turns off L3. See the pic for my "solution", which I post merely for educational purposes. I believe it meets the requirements of the question as given, but only if each statement is tested individually. However, the "question" causes ambiguities about the state of the lamps when coded into a PLC. The question did not specify the "all-off", "all-on", or even 2 on together.

In my opinion, this is a BAD way to teach the fundamentals of PLC programming, unless of course the "questioner" was hoping that students would see the ambiguities. However, in this case there should have been follow-on questions like "What happens if more than 1 switch is pressed". Without those follow-on questions, students will not learn the way PLCs work, and will continue to make basic mistakes.

Now I wonder if I would have been marked down for presenting a ladder solution that met the requirements of the question, but didn't meet the requirements of the questioner.

PS. My ladder solution is done in Logix5000, which allows the (to some) strange logic constructs, such as serial output instructions, and their placement on the rung.

ydtech · Feb 18, 2012

Nowhere does it state the program needs to be a one-liner. Divving it up in three rungs will get you there in a much more logical way.

So, for all on on no switch:
L1 = NOT S1
L2 = NOT S2
L3 = NOT S3

For all off on no switch:
L1 = S2 OR S3
L2 = S1 OR S3
L3 = S1 OR S2

From there the ladder practically writes itself.

daba · Feb 19, 2012

ydtech said:
Nowhere does it state the program needs to be a one-liner. Divving it up in three rungs will get you there in a much more logical way.

I was not suggesting it did - I simply formulated my logic in the most concise way, that's the way I think - less program, less memory usage, faster scan time.

The whole point of my post was to highlight the inadequacy of the original set question.

Which of course is mitigated by the number of responses to what is a very basic logic operation. If the question had been set properly, without leaving the door open for ambiguity, it would have all been done and dusted by now, and the OP will be well on his way to the next problem, having then understood the basic rules of ladder execution, and interpretation of a specification. It is simply not good enough to just derive code to solve a problem without regard for the "what-if?" scenarios.

Of course, the OP may not have posted the entire text of the said question. It may well have been worded like...

"With no switches pressed, all lamps should be OFF, and assume that only one switch can be pressed at any one time, code the following...." - or similar.

... in which case the OP is at fault for not providing enough information.

Which all goes to highlight that incomplete specification always causes issues.

MasterBlaster · Feb 19, 2012

daba said:
ydtech has raised a good point.

All too often I have seen test and exam questions, homework assignments, course material, clients specifications, functional specifications, et al, that have this "incompleteness" or "ambiguity".

When I saw the original "specification", I turned it on it's head, and decided that a simple solution would be for all lamps to be on initially, and that S1 turns off L1, S2 turns off L2, and S3 turns off L3. See the pic for my "solution", which I post merely for educational purposes. I believe it meets the requirements of the question as given, but only if each statement is tested individually. However, the "question" causes ambiguities about the state of the lamps when coded into a PLC. The question did not specify the "all-off", "all-on", or even 2 on together.

In my opinion, this is a BAD way to teach the fundamentals of PLC programming, unless of course the "questioner" was hoping that students would see the ambiguities. However, in this case there should have been follow-on questions like "What happens if more than 1 switch is pressed". Without those follow-on questions, students will not learn the way PLCs work, and will continue to make basic mistakes.

Now I wonder if I would have been marked down for presenting a ladder solution that met the requirements of the question, but didn't meet the requirements of the questioner.

PS. My ladder solution is done in Logix5000, which allows the (to some) strange logic constructs, such as serial output instructions, and their placement on the rung.

Daba:

Your logic rung will cause all the lamps to go off for the duration of time that any button is pressed. Is that your intent?

Bill

Guys Plz Help me out with this ladder Program.

sanilbalakrishnan

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shooter

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iant

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vikas1947

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vikas1947

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vikas1947

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