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Old May 21st, 2004, 08:00 PM   #1
flashman
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Question Allen-Bradley program symbols for ladder logic

My question is in regard to the XIO, XIC symbols for Allen-Bradley ladder logic programming.
Basically, When an input or output is on, is it shown by a N.O. set of contacts?
Then when it is off, it is shown by a N.C. set of contacts?
So, XIO=ON and XIC=OFF.
Not electrically, where N.C.= on and energized, and N.O.= off and de-energized?

-It’s been a while since I last programmed and I’d appreciate it if someone could advise me.

flashman
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Old May 21st, 2004, 08:53 PM   #2
Mickey
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I have seen other post about this. Some very good. Go to search above
and type in XIC XIO
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Old May 21st, 2004, 09:21 PM   #3
flashman
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Thanks for the help!!
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Old May 21st, 2004, 09:23 PM   #4
AllenF
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Do a search for "Imaginary Relay" by Terry Woods.

It's a colorful read.
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Old May 21st, 2004, 09:51 PM   #5
flashman
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Lightbulb

So, imaginarily speaking, the n.o. contact symbol means "on" or true and the n.c. contact symbol means "off" or false.
If I just think of it as a series of on/off conditions generating an output then I'll be OK. Otherwise, I may need a beer!

Thanks for the imaginary reality check!
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Old May 22nd, 2004, 11:55 AM   #6
Tom Jenkins
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XIC and XIO are "Allen Bradley speak" for NO and NC contacts. Nobody else uses that nomencalture. Others may disagree, but if you understand ladder diagram schematics stick with NO and NC and pull the symbol from the menu and you will be OK.
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Old May 23rd, 2004, 09:16 AM   #7
gmultani52
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XIC, instruction, instruct the processor, input in the field (XIC = Examine if closed)) if so then get the ladder true.
XIO, Exaim if open if so then get the ladder true.
I remember this way.
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Old May 24th, 2004, 08:58 AM   #8
msinclair
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Quote:
XIC and XIO are "Allen Bradley speak"
Tom is right - only AB uses these terms. You'll probably see from some of the other recommended posts that this can cause a good deal of confusion.

Just remember that

XIC means: "true if a one is at that data table address"
XIO means: "true if a zero is at that data table address"

Marc
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Old May 24th, 2004, 02:54 PM   #9
Kim Gold
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Here are a couple of pictures which might help.
In the first picture, I:1/0 = 0 and you can see O:2/0 is Off and O:2/1 is On.
Attached Images
File Type: jpg off.jpg (40.8 KB, 309 views)
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Old May 24th, 2004, 02:54 PM   #10
Kim Gold
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In the 2nd picture, I:1/0 = 1 and you can see O:2/0 is On and O:2/1 is Off.



Kim
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File Type: jpg on.jpg (38.8 KB, 297 views)
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Old May 24th, 2004, 06:38 PM   #11
flashman
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true or not true

Thanks for the picture!
I'm thinking of the input as being true enabling the output and not true to disable the output?
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Old May 25th, 2004, 08:15 AM   #12
msinclair
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Have a look at Allen's post here.

I think you have it - but if not, Allen's explanation should firm it up for you.

Marc
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Old May 25th, 2004, 05:37 PM   #13
Bitmore
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XIC examine if closed
XIO examine if open
refer to the state of an input or memory coil.
The reference above about Allen Bradley is correct, the definition was misleading.
If the field device (or memory coil on) provides a complete circuit to the PLC input a XIC bool command will cause the rung output to be true or active.
If the conditions of the input device are the same, a XIO bool command will cause the rung output to be false.

Bitmore
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Last edited by Bitmore; May 25th, 2004 at 05:47 PM.
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