1 input 3 outputs

guest

Guest
G
Is there any way to make one input turn on 3 outputs one at a time?
Leave one on untill the next one is turned on.
Do this without using osr or counter or timer.

I am not in any class.

I am trying to learn plc programming though.

Thanks

Guest
 
Not sure of your intentions per your second sentence. But to make three outputs come on off of one input just put the three output coils in parallel with each other and the one input will trigger the three outputs.
 
No, I think he wants to make a flip-flop, only with three states in stead of two (triple-flop ?).
Maybe he can modify one of the many flip-flop code examples that can be found on this site.
Use the search function and specify "flip flop" as the search string.
 
Guest,

If you're not doing this as part of a class assignment, why the arbitrary restriction against using a counter or a one-shot?

If it's simply for the intellectual challenge, why ask somebody else to do it for you?

The answer to your question is yes.
 
Well, one obvious answer is a drum timer. However, what you stated you want to do is, to some extent, impossible or at least implausible. As I interpret your statement, you want to have the ouptuts turn on in sequence after a single input transition starts the process, so you have to have something that identifies when the first output's sequence is over and it is time to turn on the next output.

Or do you mean that each subsequent press of a momentary pushbutton will step the outputs through the sequence one at a time? In that case a drum timer can still work, as will bit shifts (bleach!) or adds and compares, or holding coils and flag bits, or lots of other techniques.

Properly phrasing the question is the hardest part of getting a good answer.

And, I must confess, I take your claim of not being a student with a grain of salt!
 
Question restated

no bit shift, no osr, no counter, no timer

1 input, 1st output on and still on
1 (same)input again, 1st output off and 2nd output on and still on
1 (same)input again, 2nd output off and 3rd output on and still on

Steve Bailey, are you calling me a Liar?
But, thanks for your answer.

Thanks

guest
 
Guest,

Please don't turn this into an ad hominem discussion. Classroom instructors are fond of applying arbitrary restrictions on their students' solutions in order to force them to apply a specific technique to the problem.

If you're trying to program a real-world application, then your question is akin to asking "Is there any way I can build a house without using a hammer?" The answer is "yes", but it invites the follow-up question "Why?"
 
Steve,

The answer to why was in the first post.
Hint: The last sentence.
& I never asked anybody to do it for me.

Thank you JesperMD & panic mode for flip-flop info

Thanks


guest
 
Without a oneshot, how do you expect the 'circuit' not to fly through all 3 states in the 100msec the button is down?

And, by not making use of the structure elements provided (including one-shots, timers, and counters) you aren't learning much about plc's.
 
***you aren't learning much about plc's.***

Beg to differ, but skipping the basics is not in the interest of aspiring programmers... One might learn enough to troubleshoot the odd PLC program, but he/she won't gain an intimate knowledge of Boolean operations if they don't, or can't work through little challenges such as this... This material is at the heart of all programming languages, and whether you apply it using assembly language instructions, VB logical instructions, or ladder logic instructions, etc.,,, the task is the same, and learning how to solve such puzzles is key to becoming a good programmer... Anyone can use a TON timer, or a Do-Every-Thing instruction, but can you make 3 lights flash in sequence in response to a switch closure using assembly language... If you take up the challenge that this instructor has set out for the students, you just might learn enough to tackle such a problem in any language, on any computer.... Remenber that the WhizBangDoEverthing instruction is only available on Acme PLCs and it's not truly an instruction but rather a built in routine...kinda like the "Move to Perch" instruction in GMF/Karel... Of course you could write your own if you knew the basics...

The most difficult programming instructions to learn are the basic ones, and most people simply skip over the basics if given a chance... Obviously our guest has an instructor who isn't about to allow that, and the challenge is clear...

Picture yourself connected to a PLC2 family processor which lacks an OSR instruction..
Limit yourself to the basic relay instructions (XIO, XIC,OTE,OTL,OTU), and now you will have to think!!!
Of course that may be just what the instructor had in mind...

BTW... telling the student to do a search for a solution that he/she can simply copy has it's flaws also....
PS: I'm not the instructor..
 
If First Scan - Set FirstScan
If Input and Output 3 or FirstScan - Set Output 1, Reset Output 3, Reset FisrtScan
If Input and Output 1 - Set Output 2, Reset Output 1
If Input and Output 2 - Set Output 3, Reset Output 2
 
Bill Simpson hit it right on the nose with his reply.
I used to give this little task to the maint. techs at the end of there training. It's amazing how many of them get stumped and swear it cant be done with just plain old internal relays and NOTHING else, NO SET or RESETING relays either. I really like this exercise because it makes you think and become part of the plc as Bill stated.

guest,
Take it one step at a time. You said first input on turn on first output and output stay on. I think you already have gotten this far.
Now, what is new to the plc when you turn the input back off? Input off, BUT ouput 1 on. Now use this to turn on a internal relay and hold it on, naming it "output 1 on ack". When you go turning the input on again what is different from the last time you turned it on? I haven't giving you all the answers, but think about it. If this is not a school project, you will still get a lot more out of it then somebody telling you the whole answer. PLUS, the whole meaning of the project is to make you THINK.
GOOD LUCK
TIM beerchug
 
Not a bad start, but it doesn't work.

Let's assume that we're well past the first scan, but haven't turned on Input yet. Output 1 should be ON, Output 2 and Output 3 are both OFF.

When you turn on Input, line 3 turns ON Output 2 and turns OFF Output 1. So far, so good. But when the PLC gets to line 4, Output 2 is ON, so Output 3 gets turned ON and Output 2 gets turned right back OFF.

Reverse the order of lines 2, 3, and 4, and it almost works if Input is a one-shot.
 
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