Rockwell Automation 9323-PA1E USER MANUAL APS 6.0 - Manual (Page 58)

Preface
Advanced Programming Software User Manual
4–4
The status of the instruction is
If the data table
bit is
XIC
Examine if Closed
] [
XIO
Examine if Open
]/[
OTE
Output Energize
( )
Logic 0 False True False
Logic 1 True False True
From the above table, we see that status bits 10, 11, and 12 indicate that the XIC
instruction, XIO instruction, and OTE instruction of our rung are all true. The
true/false state of instructions is the basis of controller operation, as indicated in the
following sections.
Logical Continuity
During controller operation, the processor determines the on/off state of the bits in
the data files, evaluates the rung logic, and changes the state of the outputs
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 shows the on/off state of output B3/12 as determined by the
changing states of the inputs in the rung.
XIC XIO OTE
Input Instructions Output Instructions
B3
10
B3
11
B3
12