Can somebody explain this short program

Greetings all,
I found this programs amongst the literature I kept from my first and only basic PLC class which I thought I took a few years ago (how about 2002…) and plugged it in logixPro. Now, I want to make sure I understand what I’m seeing! When it’s turned on and the timer reaches 20 motor 2 turns on for .2 seconds and then motor 1 turns on at .3 seconds, and keeps on running…. Unless I put in the XIO instruction to stop it. I am correct?
1- My first question is, what is the 0014h at the bottom of the input instruction .
2- My second question is where would you put this type programming, its obvious it would control two motors...

Rung 0:
I:1/0 is the Stop button input, configured as NC to energize the input if not pushed.
I:1/1 is the Start button input, configured as NO to energize the input if pushed.
When I:1/1 is pushed, B3:0/0 is energized and held on even if I:1/1 is released, until I:1/0 is pushed.
Rung 1:
B3:0/0 when energized will start Timer T4:0
Rung 2:
When Timer T4:0 accumulator reaches 30 (3 seconds), T4:0/DN (Done) bit will energize Output O:2/0
Rung 3:
When Timer T4:0 accumulator (GRT instruction) reaches 20 (2 seconds), and before the Timer T4:0 accumulator reaches 30 (3 seconds),
Output O:2/1 will energize. When Timer T4:0 accumulator reaches 30 (3 seconds), Output O2:0/1 will
de-energize.
Rung 4:
The End instruction will Return execution back to the Top Rung.

Therefore it would be an AND and AND and not an AND and OR on rung 0

Sometimes the N.O. N.C. can be confusing even the ladder logic says otherwise.

jrwb4gbm said:

Rung 0:
I:1/0 is the Stop button input, configured as NC to energize the input if not pushed.
.

Click to expand...

kapooski2012 said:

Therefore it would be an AND and AND and not an AND and OR on rung 0

Sometimes the N.O. N.C. can be confusing even the ladder logic says otherwise.

Click to expand...

Confusion arises possibly because you are thinking of the instructions as Normally-Open and Normally-Closed contacts.

As I just stated the -| |- and -|/|- are instructions to the processor to go and look at the address specified, and return a true or false depending on the instruction type, and the state of the bit examined.

Allen-Bradley, in their wisdom, deliberately did not name these instructions as NO and NC, to try and overcome the confusion.

Their proper names are ....

-| |- XIC : eXamine If Closed : Put another way, return TRUE if this bit is ON, FALSE if OFF.

-|/|- XIC : eXamine If Open : Put another way, return TRUE if this bit is OFF, FALSE if ON.

If you can overcome the habit of thinking of the instructions as normally-open and normally-closed contacts, you will reap the benefit, especially when faced with a situation where a field device's normally-closed contact is inspected in the code with a -| |- instruction, and vice-versa

kapooski2012 said:

Therefore it would be an AND and AND and not an AND and OR on rung 0

Sometimes the N.O. N.C. can be confusing even the ladder logic says otherwise.

Click to expand...

Confused? These two links will clear it up for you.:nodi:

http://www.plctalk.net/qanda/showthread.php?postid=11397#post11397

http://www.plctalk.net/qanda/showthread.php?t=3486

I guess I wasn't completely clear in my description about the Stop Button Input NC. I was referring to the physical button contacts on the device. The same applies to the Start Button Input NO. I was referring to the physical button contacts on the device. Maybe even this description is confusing.

That's it , after putting it throu the program, swapping a couple of times (it made sense, and after reading the rest of the thread and the addtionanl links...whoa!!!)I think I can tell the difference, but I'll read it again,again! (sometimes it sinks-in after reading something several times. (English being my second language, French-Canadian my first, with the slang and all)