Omron CQM1H - PROGRAM Programming Manual page 237

Data Areas, Definer Values, and Flags
Indirect Addressing
Designating Constants
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can, however, be crossed for a single operand, i.e., the last bit in the IR area
may be specified for an operand that requires more than one word as long as
the SR area is also allowed for that operand.
The Flags subsection lists flags that are affected by execution of an instruc-
tion. These flags include the following SR area flags.
Abbreviation
ER Instruction Execution Error Flag
CY Carry Flag
GR Greater Than Flag
EQ Equals Flag
LE Less Than Flag
ER is the flag most commonly used for monitoring an instruction's execution.
When ER goes ON, it indicates that an error has occurred in attempting to
execute the current instruction. The Flags subsection of each instruction lists
possible reasons for ER being ON. ER will turn ON if operands are not
entered correctly. Instructions are not executed when ER is ON. A table of
instructions and the flags they affect is provided in Appendix B Error and
Arithmetic Flag Operation.
When the DM area is specified for an operand, an indirect address can be
used. Indirect DM addressing is specified by placing an asterisk before the
DM: *DM.
When an indirect DM address is specified, the designated DM word will con-
tain the address of the DM word that contains the data that will be used as the
operand of the instruction. If, for example, *DM 0001 was designated as the
first operand and LR 00 as the second operand of MOV(21), the contents of
DM 0001 was 1111, and DM 1111 contained 5555, the value 5555 would be
moved to LR 00.
MOV(21)
*
DM 0001
LR 00
When using indirect addressing, the address of the desired word must be in
BCD and it must specify a word within the DM area. In the above example, the
content of *DM 0000 would have to be in BCD between 0000 and 1999.
Although data area addresses are most often given as operands, many oper-
ands and all definers are input as constants. The available value range for a
given definer or operand depends on the particular instruction that uses it.
Constants must also be entered in the form required by the instruction, i.e., in
BCD or in hexadecimal.
Name
Word Content
DM 0000
DM 0001
Indirect
DM 0002
address
DM 1111
DM 1113
DM 1114
Section 5-3
Bit
25503
25504
25505
25506
25507
4C59
1111
Indicates
F35A
DM 1111.
5555
2506
5555 moved
to LR 00.
D541