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70
Introduction
Section 4-1
4-1
Introduction
Most data areas in the CPM2B can be accessed as bits or words. (The TR
Area can be accessed by bit address only and the DM Area can be accessed
by word address only.)
The following diagram shows the structure of the IR Area and the relationship
between bit and word addresses.
Note
1.
Input bits IR 00108 to IR 00111 for 32-point CPU Boards reflect the status
of the DIP switch on the CPU Board.
2.
The contents of the HR Area, AR Area, Counter Area, and read/write DM
Area are backed up by the CPU Board’s backup battery or capacitor. If the
battery or capacitor discharges completely, memory contents will be re-
turned to their default settings.
3.
The program and data in DM 6144 to DM 6655 are stored in flash memory.
Data area
Size
Words
Bits
Function
IR
Area
Input bits
160 bits
(10 words)
IR 000 to IR 009
IR 00000 to IR 00915
(See note 1.)
These bits can be allocated to the external
I/O terminals.
Output bits
160 bits
(10 words)
IR 010 to IR 019
IR 01000 to IR 01915
Work bits
928 bits
(58 words)
IR 020 to IR 049
IR 200 to IR 227
IR 02000 to IR 04915
IR 20000 to IR 22715
Work bits can be freely used within the pro-
gram.
SR Area
448 bits
(28 words)
SR 228 to
SR 255
SR 22800 to SR 25515
These bits serve specific functions such as
flags and control bits.
TR Area
8 bits
---
TR 0 to TR 7
These bits are used to temporarily store
ON/OFF status at program branches.
HR Area
320 bits
(20 words)
HR 00 to HR 19
HR 0000 to HR 1915
These bits store data and retain their ON/
OFF status when power is turned OFF.
AR Area
384 bits
(24 words)
AR00 to AR 23
AR 0000 to AR 2315
These bits serve specific functions such as
flags and control bits.
LR Area
256 bits
(16 words)
LR 00 to LR 15
LR 0000 to LR 1515
Used for a 1:1 data link with another PLC.
Timer/Counter
Area
256 bits
TIM/CNT 000 to TIM/CNT 255
The same numbers are used for both tim-
ers and counters.
DM
Area
Read/write
2,026
words
DM 0000 to DM 1999
DM 2022 to DM 2047
DM Area data can be accessed in word
units only. Word values are retained when
the power is turned OFF.
The read-only area and PLC Setup cannot
be overwritten from program. Change these
settings with a Programming Device.
Error log
22 words
DM 2000 to DM 2021
Read-only
456 words
DM 6144 to DM 6599
PLC Setup
56 words
DM 6600 to DM 6655
Bit number
IR 000
IR 001
IR 010
IR 011
IR 00011
Word Bit number
IR 01107
Word Bit number
Bit addresses
15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
W
o
rd addresses
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