USER MANUAL APS 6.0

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, 1

1, 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. W

e 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. W

e 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