I/O Memory Area Overview; I/O Memory Areas - Omron CJ2 - 02-2010 User Manual

6 I/O Memory Areas

6-1 I/O Memory Areas
6-1-1

I/O Memory Area Overview

I/O memory areas can be accessed using instruction operands. The following table lists the areas in I/O
Memory.
Area name
CIO Area (Core I/O Area)
I/O Area
Data Link Area
Synchronous Data
Refresh Area
CPU Bus Unit Area
Special I/O Unit Area
Serial PLC Link Area
DeviceNet Area
Internal I/O Area *1
Work Area (W) *1
Holding Area (H)
Auxiliary Area (A)
Temporary Relay Area
(TR) (TR Area)
Data Memory Area (D)
(DM Area)
Extended Data Memory
Area (E)
(EM Area)
Timer Timer Comple-
Areas tion Flag Area
(T)
Timer PV Area
(T)
6-2
Words in the CIO Area are used for data exchanges such as I/O refreshing with
various Units. Words that are not allocated to Units may be used as work words
and work bits in the program. It is not necessary to input the "CIO" prefix when
specifying an address in the CIO Area.
Words in the I/O Area are allocated to external I/O terminals on Basic I/O Units. 6-8
Words in the Data Link Area are used for data links with other PLC Units on a
network through a Controller Link Unit.
Words in the Synchronous Data Refresh Area are allocated as synchronous
refresh data when synchronous unit operation is used.
Words in the CPU Bus Unit Area are allocated to CPU Bus Units to transfer sta-
tus information.
Words in the Special I/O Unit Area are allocated to Special I/O Units to transfer
status information.
This area is used for Serial PLC Links. Data is exchanged between CPU Units
using serial ports without communications programming. This area is supported
only by CJ2M CPU Units.
Words in the DeviceNet Area are allocated to slaves for DeviceNet remote I/O
communications. Allocations in this area are fixed and cannot be changed.
These words can be used only in the program. They cannot be used for I/O
exchange with external I/O terminals.
Words in the Work Area can be used only in the program.
Words in the Holding Area can be used only in the program. These words retain
their content when the PLC is turned ON or the operating mode is switched
between PROGRAM mode and RUN or MONITOR mode.
The Auxiliary Area contains flags and control bits used to monitor and control
PLC operation.
The TR Area contains bits that record the ON/OFF status of program branches.
The TR bits are used with mnemonics only.
The DM Area is a multi-purpose data area. With CJ2 PLCs, the DM Area can be
read and written in either word units or bit units.
Words in the DM Area retain their contents when the PLC is turned ON or the
operating mode is switched between PROGRAM mode and RUN or MONITOR
mode.
Some words in the DM Area are used to store initial settings for Special I/O
Units and CPU Bus Units.
The EM Area is a multi-purpose data area. With CJ2 PLCs, the EM Area can be
read and written in either word units or bit units.
Words in the EM Area retain their content when the PLC is turned ON or the
operating mode is switched between PROGRAM mode and RUN or MONITOR
mode. The EM Area is divided into banks.
A Completion Flag is turned ON when the set time of the timer elapses.
The PV of a timer increases or decreases as the timer operates.
Description
CJ2 CPU Unit Software User's Manual
Reference
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6-18
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