Omron CP1H-X40D Operation Manual page 205

Data Memory Area (D)
Forcing Bit Status
Indirect Addressing
DM Area Allocation to
Special I/O Units
1,2,3...
Bits in the DM Area cannot be force-set or force-reset.
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 0000 to 7FFF.
0100
@D100
Address actually used.
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 0000 to 9999.
*D100
0100
Address actually used.
Parts of the DM Area are allocated to Special I/O Units and CPU Bus Units for
functions such as initial Unit settings. The timing for data transfers is different
for these Units, but may occur at any of the three following times.
1. Transfer data when the PLC's power is cycled or the Unit is restarted.
2. Transfer data once each cycle.
3. Transfer data when required.
Refer to the Unit's operation manual for details on data transfer timing.
Special I/O Units (D20000 to D29599)
Each Special I/O Unit is allocated 100 words based on unit numbers 0 to 95.
Refer to the Unit's operation manual for details on the function of these words.
DM Area for Special I/O Units
(100 words/Unit)
D256
D100
Special I/O Unit
CPU Unit
Data trans-
ferred to the
Special I/O
unit when the
PLC is turned
ON or the Unit
is restarted.
Data trans-
ferred to the
CPU Unit at
cyclic refresh-
ing or when
necessary.
Section 4-14
171