Data Memory Area - Omron CJ2 CPU UNIT SOFTWARE User Manual

6-14 Data Memory Area

The DM Area addresses range from D0 to D32767 for words. This data area is used for general data
storage and manipulation and is accessible by word or bit.
Data in the DM Area is retained when the PLC's power is cycled or the CPU Unit operating mode is
changed from PROGRAM mode to RUN/MONITOR mode or vice-versa.
Bits in the DM Area cannot be force-set or force-reset.
Indirect Addressing
Words in the DM Area can be indirectly addressed in two ways: binary-mode and BCD-mode.
Binary-mode Addressing (@D)
When a "@" character is input before a DM address, the content of that DM word is treated as binary
and the instruction will operate on the DM word at that binary address. The entire DM Area (D0 to
D32767) can be indirectly addressed with hexadecimal values 0 to 7FFF.
BCD-mode Addressing (*D)
When a "*" character is input before a DM address, the content of that DM word is treated as BCD
and the instruction will operate on the DM word at that BCD address. Only part of the DM Area (D0
to D09999) can be indirectly addressed with BCD values 0 to 9999.
Example: [ MOV #1234 *D100 ]
CJ2 CPU Unit Software User's Manual
0100 hex
@D100
Address actually used
*D100
0100 hex
Address actually used
6 I/O Memory Areas
D256
1234 hex
D100
6
6-25