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Appendix C
Memory Areas
CPM1/CPM1A Memory Areas
Memory Area Structure
The following memory areas can be used with the CPM1/CPM1A.
Data area
Words
Bits
Function
IR area
1
Input area
IR 000 to IR 009
(10 words)
IR 00000 to IR 00915
(160 bits)
These bits can be allocated to the external
I/O terminals.
Output area
IR 010 to IR 019
(10 words)
IR 01000 to IR 01915
(160 bits)
/O e
a s
Work area
IR 200 to IR 231
(32 words)
IR 20000 to IR 23115
(512 bits)
Work bits can be freely used within the pro-
gram.
SR area
SR 232 to SR 255
(24 words)
SR 23200 to SR 25515
(384 bits)
These bits serve specific functions such as
flags and control bits.
TR area
---
TR 0 to TR 7
(8 bits)
These bits are used to temporarily store
ON/OFF status at program branches.
HR area
2
HR 00 to HR 19
(20 words)
HR 0000 to HR 1915
(320 bits)
These bits store data and retain their ON/
OFF status when power is turned off.
AR area
2
AR 00 to AR 15
(16 words)
AR 0000 to AR 1515
(256 bits)
These bits serve specific functions such as
flags and control bits.
LR area
1
LR 00 to LR 15
(16 words)
LR 0000 to LR 1515
(256 bits)
Used for a 1:1 data link with another PC.
Timer/Counter area
2
TC 000 to TC 127 (timer/counter numbers)
3
The same numbers are used for both timers
and counters.
DM area
Read/write
2
DM 0000 to DM 0999
DM 1022 to DM 1023
(1,002 words)
---
DM area data can be accessed in word
units only. Word values are retained when
the power is turned off.
Error log
2
DM 1000 to DM 1021
(22 words)
---
Used to store the error code of errors that
occur. These words can be used as ordi-
nary read/write DM when the error log func-
tion isn’t being used.
Read-only
4
DM 6144 to DM 6599
(456 words)
---
Cannot be overwritten from program.
PC Setup
4
DM 6600 to DM 6655
(56 words)
---
Used to store various parameters that con-
trol PC operation.
Note
1. IR and LR bits that are not used for their allocated functions can be used as work bits.
2. The contents of the HR area, AR area, Counter area, and read/write DM area are backed up by a capaci-
tor. The backup time varies with the ambient temperature, but at 25
C, the capacitor will back up
memory for 20 days. If the power supply is off longer than the backup time, memory contents will be
cleared and AR1314 will turn ON. (This flag turns ON when data can no longer be retained by the built-in
capacitor.) Refer to
2-1-2 Characteristics
in the
CPM1 Operation Manual
for a graph showing the back-
up time vs. temperature.
3. When accessing a PV, TC numbers are used as word data; when accessing Completion Flags, they are
used as bit data.
4. Data in DM 6144 to DM 6655 cannot be overwritten from the program, but they can be changed from a
Programming Device.
SR Area
These bits mainly serve as flags related to CPM1/CPM1A operation or contain present and set values for various
functions. The functions of the SR area are explained in the following table.
Note
“Read-only” words and bits can be read as status in controller PC operation, but they cannot be written from
the ladder program. Bits and words that are “Not used” are also read-only.
