Rockwell Automation 9323-PA1E QUICK START GUIDE APS 6.0 - Manual (Page 27)

Preface
APS Quick Start for New Users
2–10
Logical Continuity
During controller operation, the processor evaluates each rung, changing the status
of instructions according to the logical continuity of rungs. More specifically, input
instructions set up the conditions under which the processor will make an output
instruction true or false. These conditions are:
•
When the processor finds a continuous path of true input instructions in a rung,
the OTE output instruction will become (or remain) true. We then say that “rung
conditions are true”.
•
When the processor does not find a continuous path of true input instructions in
a rung, the OTE output instruction will become (or remain) false. We then say
that “rung conditions are false”.
The figure below indicates the data file conditions under which the rung is true:
Input Data File
address data
I:1 0001
Status bit I:1/0 is a logic
1, making the XIC
instruction true.
Output Data File
address data
O:3 0000 0001
XIC
( )
O:3
0
] [
I:1
0
]/[
I:1
1
XIO OTE
Input Instructions Output Instruction
Status bit I:1/1 is a logic
0, making the XIO
instruction true.
The processor changes status bit O:3/0 to a
logic 1, because a continuous path of true
input instructions exist in the rung.
In the above example, if the input data file was 0000, then the rung would be false
and the output data file would read as 0000 0000.