Chapter 5 Power Supply / CPU

5.5Operation Modes

The CPU operates in one of the four modes - RUN, STOP, PAUSE and DEBUG mode. The following describes ope ration processing in each operation mode.

5.5.1 RUN Mode

In this mode, programs are normally operated.

The first scan start in the RUN mode

Initialize data area according to the preset restart mode.

Check the program and determine it can be executed or not.

Execute input refresh

Execute programs and tasks

Check the availability of expansion units

Execute communication and internal service

Execute output refresh

No

Operation mode is changed?

Yes

Operate with new mode

1) Processing when the operation mode is changed.

Initialization

of

data area

is

executed when the first scan starts and The possibility of execution of the program

is decided

with

check on

its

effectiveness.

2) Operation processing contents

I/O Refresh and program operation are executed.

(1)Interrupt programs are executed with the detection of their start-up conditions.

(2)Normal or abnormal operation and mounting conditions of the loaded module are checked.

(3)Communications service or other internal operations are processed.

5-19

Page 56
Image 56
LG Electronics 120S user manual Operation Modes, RUN Mode, Processing when the operation mode is changed