push button to turn on and off light - PLCS.net

hasan_ali · January 7th, 2008, 01:56 AM

Dear,
I have an exercise that i have to turn on and turn off the light with the same push button. How would be the ladder? i am using Allen Bradley Control Logix PLC.

ggchavhan · January 7th, 2008, 02:13 AM

Mr Ali
hi

You have to use X_Or logic, or you can use ROL instruction. No of ways this logic can develop.

Ken Moore · January 7th, 2008, 04:59 AM

This topic has been covered many many many times. Search the site for "flip flop".

capnahab · January 7th, 2008, 06:16 AM

There are two ways to attack the problem. Either use complicated ladder logic or a two position switch. The problem today is that everybody is trying to fix problems with the PLC when simple hardware logic triumphs. I am a simple hardware person who hates computers.

parky · January 8th, 2008, 07:10 AM

look at previous post about turning on an output with one push button

ggchavhan · January 8th, 2008, 07:29 AM

pb b3:0/0 b3:0/1
|----| |-----[OSR]--------------()
|
| b3:0/1 Lamp lamp
|----| |---|\|------|----------( )
| |
| b3:0/1 Lamp |
|----|\|---| |------|
|
|

hasan_ali · January 8th, 2008, 10:15 PM

Thanks to everybody for giving so useful suggestions.
Previously i was using the counter to count the number of times the push button is pressed. and using its ACC value to latch and unlatch the light. It was causing the program longer and using more memory because i had to control several lights through push buttons.
Now i followed the concept of flip flop.
Ken, i got that and completed the exercise.
ggchavhan, simplified in a good way.

Scharbag · February 2nd, 2009, 08:57 AM

I love the internet sometimes...

I needed to have a latching solution to allow the flip-flop to be retentitive and possibly manipulated durring initial PLC startup. There is a nice PDF, which exists in this forum, that has 10 flip-flop examples. These examples helped me figure this problem out. I was sooo close to the solution, missing on small line of code which the PDF pointed out to me. Ladder logic is neat stuff once you pull your head from your but... Now they need a latch command in function block that works!

Cheers,

Dave

January 7th, 2008, 01:56 AM	#1
hasan_ali Member Join Date: Dec 2007 Location: Midlands Posts: 54	push button to turn on and off light Dear, I have an exercise that i have to turn on and turn off the light with the same push button. How would be the ladder? i am using Allen Bradley Control Logix PLC.

January 7th, 2008, 04:59 AM	#3
Ken Moore Member Join Date: May 2004 Location: Upstate South Carolina Posts: 2,325	This topic has been covered many many many times. Search the site for "flip flop". __________________ "To give real service you must add something that cannot be bought or measured with money; and that is sincerity and integrity." - Donald A. Adams

January 8th, 2008, 07:10 AM	#5
parky Member Join Date: Oct 2004 Location: Midlands Posts: 939	look at previous post about turning on an output with one push button Last edited by parky; January 8th, 2008 at 07:16 AM.

January 8th, 2008, 07:29 AM	#6
ggchavhan Member Join Date: Nov 2006 Location: pune Posts: 128	Look the logic pb b3:0/0 b3:0/1 \|----\| \|-----[OSR]--------------() \| \| b3:0/1 Lamp lamp \|----\| \|---\|\\|------\|----------( ) \| \| \| b3:0/1 Lamp \| \|----\|\\|---\| \|------\| \| \|

January 8th, 2008, 10:15 PM	#7
hasan_ali Member Join Date: Dec 2007 Location: Midlands Posts: 54	Resolved Thanks to everybody for giving so useful suggestions. Previously i was using the counter to count the number of times the push button is pressed. and using its ACC value to latch and unlatch the light. It was causing the program longer and using more memory because i had to control several lights through push buttons. Now i followed the concept of flip flop. Ken, i got that and completed the exercise. ggchavhan, simplified in a good way.



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January 7th, 2008, 02:13 AM	#2
ggchavhan Member Join Date: Nov 2006 Location: pune Posts: 128	Mr Ali hi You have to use X_Or logic, or you can use ROL instruction. No of ways this logic can develop.

January 7th, 2008, 06:16 AM	#4
capnahab Member Join Date: Jan 2008 Location: ATLANTA Posts: 5	There are two ways to attack the problem. Either use complicated ladder logic or a two position switch. The problem today is that everybody is trying to fix problems with the PLC when simple hardware logic triumphs. I am a simple hardware person who hates computers.

February 2nd, 2009, 08:57 AM	#8
Scharbag Member Join Date: Feb 2009 Location: Saskatoon Posts: 1	I love the internet sometimes... I needed to have a latching solution to allow the flip-flop to be retentitive and possibly manipulated durring initial PLC startup. There is a nice PDF, which exists in this forum, that has 10 flip-flop examples. These examples helped me figure this problem out. I was sooo close to the solution, missing on small line of code which the PDF pointed out to me. Ladder logic is neat stuff once you pull your head from your but... Now they need a latch command in function block that works! Cheers, Dave Last edited by Scharbag; February 2nd, 2009 at 09:05 AM.

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