I WANT TO SWITCH ON ONE OUTPUT USING ONLY ONE PUSH BUTTON (WITHOUT USING TIMER SET RESET PULSE COUNTER JUST PURE NO NC LOGIC)
PURE NO NC LOGIC ONLY

I WILL BE VERY THANKFUL TO ALL OF YOU IF YOU GIVE ME THIS ANSWER. IT WAS ASKED TO ME IN ONE INTERVIEW BUT I FAILED TO ANSWER. BUT I WANT TO KNOW HOW IT IS POSSIBLE USING ONLY NO NC CONTACTS ONLY.

 

How about this:


http://members.cox.net/stevemyres/pics/PushOnPushOff.jpg

 

>I WANT TO SWITCH ON ONE OUTPUT USING
>ONLY ONE PUSH BUTTON (WITHOUT USING
>TIMER SET RESET PULSE COUNTER JUST PURE
>NO NC LOGIC)

<pre>
IN Q Q
+--| |----|/|--+--( )--
| |
| IN Q |
+--|/|----| |--+
</pre>

 

Create a Holding contact.

 

I'll give you a hint - monitor whether a bit is the same as it was at the end of the last scan to simulate the function of the normal one-shot you will need to make a secure toggle. Once you've done that there are several ways, examples in link attached - note the one by "potter" won't work.

http://www.plctalk.net/qanda/showthread.php?t=13204&highlight=toggle+timer

 

There is no way

 

Hello,

Yes there is a way.

You just need to create a few flip-flops - latches.

Not all PLC's contain latches so you have to create them.

Then using each off to on change of the input the output toggles.

Good luck,

Mark
http://www.peakhmi.com/

 

To Friedrich Haase: nice solution.

To HARISH. The all-caps made it harder for me to understand your question.

-James Ingraham
Sage Automation, Inc.

 

USING A MOMENTARY PUSHBUTTON WITH INTERNAL BITS AND AN OSR INSTRUCTION YOU CAN MAKE THE CIRCUIT FUNCTION AS NEEDED.

RUNG ONE: MOMENTARY PUSHBUTTION IN SERIES WITH OSR INSTRUCTION ENDING WITH INTERNAL OUTPUT NUMBER ONE.

RUNG TWO : TWO PARALLEL OPEN CONTACTS INPUT CONTACT OF RUNG ONE INTERNAL OUTPUT IN PARALLEL WITH OPEN CONTACT FROM THE INTERNAL OUTPUT ON RUNG TWO THIS COMBINATION IS IN SERIES WITH AN CLOSED CONTACT OF INTERNAL OUTPUT RUNG TWO IN PARALLEL WITH CLOSED CONTACTS LABELED RUNG ONE INTERNAL OUTPUT ENDING WITH INTERNAL OUTPUT NUMBER TWO.

RUNG THREE: OPEN CONTACTS LABELED WITH INTERNAL IN SERIES WITH OUTPUT RUNG TWO ENDING WITH OUTPUT TO BE CONTROLLED.

 

Just use a sequence with set/res. A three step interlocked sequence described below will work:

- Wait for button and set
- Wait for not button (and timer delay for switch bounce)
- Wait for button and reset

Is there a reason you don't want to use set/res?

KEJR

 

Think Flip Flop.

Regards
cww