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Old January 12th, 2012, 06:52 PM   #1
hamg81
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Fancy Exclamation Ladder to logic

HI, I DONīT REALLY KNOW A LOT ABOUT PLCīS BUT I NEED TO TRANSLATE THIS LADDER DIAGRAM TO LOGICAL GATES.
I KNOW THAT TO PARALLEL CONTACTS MAKE OR GATES AND SERIAL CONTACTS MAKE AND GATES.
SO FAR SO GOOD , THE PROBLEM IS IN THE FIRST RUNG . ?? (NOT SURE IF IīM USING THIS TERM CORRECTLY...)
THERE IS AN OUTPUT IN PARALLEL WITH A TON... SO HOW IS THAT POSSIBLE? I CANīT USE THE ONLY OUTPUT I HAVE AS AN INPUT OF A GATE, CAN I??
I HAVE ATTATCHED THE ORIGINAL DIAGRAM AND MY BEST SHOT TO TRANSLATE IT, COULD PLEASE PLEASE ANYBODY HELP ME??

THANK YOU SO MUCH!!
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Old January 13th, 2012, 01:39 AM   #2
gih
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Using the output to feed back is not un common in PLC or Logic
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Old January 13th, 2012, 01:53 AM   #3
ivo.maenen
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example:

BS-3201-B = start
or
SW-3202 = motor

If you press the start-pusbutton and example the stop-pushbutton is still NC the output SW-3202 will turn on.

After you have pressed the start-pushbutton, it will open again. So the motor would turn off if it did not kept it self high because of the instruction "OR SW-3202"

If you want to stop the motor: you press the stop-button and e.g. BS-3201 will be a logical '0'.

Parallel with the start-button you wire a NO-contact of the output = OR-function

In series with this you wire the NC-contact of the stopbutton = AND-function
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Old January 13th, 2012, 02:51 AM   #4
gih
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I don't have to much time at the moment to review the logic is this a working running program in the PLC. You can monitor the PLC IO in real time on most PLC's. Thats a good way to check what in programmers intention was.

Last edited by gih; January 13th, 2012 at 02:52 AM. Reason: Mods is text
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Old January 13th, 2012, 05:01 AM   #5
dprathamesh1
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Smile try this

What do you want exactly
you want to learn logic or somebody will write that in a language which you will understand
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Old January 13th, 2012, 07:02 AM   #6
ivo.maenen
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Quote:
Originally Posted by hamg81 View Post
I CANīT USE THE ONLY OUTPUT I HAVE AS AN INPUT OF A GATE, CAN I??

THANK YOU SO MUCH!!

Yes, you can!

Like 'gih' said: it's common.

start stop out
|----| |-------| |--------( )--
| out |
|----| |---
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Old January 13th, 2012, 11:56 AM   #7
hamg81
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Hi, thanks for the reply. I know an output can be used as feed back, what i donīt really understand is how to interpret the output sv-3202 in series with the psl-3218 and te tonīs tt this in parallel with the ton itself and the bs-3201b and the psl-3218.
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Old January 13th, 2012, 02:42 PM   #8
ivo.maenen
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SV-3202 is energised if
- timer120ms (ton?) is 'true'
or
- PSL-3218 is 'true'

timer 120ms is 'active' if:
AND BS-3201
AND BS-3201A
AND PSL-3218
AND the OR-function
are active at the same moment

the OR-function is true if:
BS-3201B
or
SV-3202
are true
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Old January 13th, 2012, 04:32 PM   #9
hamg81
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Thank you so much for your help!!
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Old January 14th, 2012, 02:06 PM   #10
Lancie1
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Quote:
I CANīT USE THE ONLY OUTPUT I HAVE AS AN INPUT OF A GATE, CAN I??
Yes, you can. That is a feature that makes logic gates more useful. The output can feed backwards to another device, or back to itself, as well as forward.

This same logic feature is implemented in nearly all PLC software programs. I have seen a few low-end PLCs (advanced programmable smart relays like the ZEN) that had limited feedback ability, or only one output allowed per rung.

Last edited by Lancie1; January 14th, 2012 at 02:09 PM.
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Old January 14th, 2012, 03:47 PM   #11
Lancie1
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Quote:
I NEED TO TRANSLATE THIS LADDER DIAGRAM TO LOGICAL GATES.
Your translated logic gate diagram does not match Rung 000 of your PLC program.
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Old January 14th, 2012, 05:09 PM   #12
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Quote:
I NEED TO TRANSLATE THIS LADDER DIAGRAM TO LOGICAL GATES.
Rung 000 Gate Logic:
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File Type: jpg Rung 000 Gate Logic.jpg (35.0 KB, 66 views)

Last edited by Lancie1; January 14th, 2012 at 05:40 PM.
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Old January 14th, 2012, 05:57 PM   #13
Lancie1
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Your Rung 000 actually looks like this:
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Last edited by Lancie1; January 14th, 2012 at 06:00 PM.
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