Omron C200HE Manual Do Utilizador

The IR and SR areas are considered as separate data areas. If an operand has
access to one area, it doesn’t necessarily mean that the same operand will have
access to the other area. The border between the IR and SR areas can, howev-
er, be crossed for a single operand, i.e., the last bit in the IR area may be speci-
fied 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 instruction.
These flags include the following SR area flags.

ER

Instruction Execution Error Flag

25503

CY

Carry Flag

25504

GR

Greater Than Flag

25505

EQ

Equals Flag

25506

LE

Less Than Flag

25507

N

Negative Flag

25402

OF

Overflow Flag

25404

UF

Underflow Flag

25405

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 C Error and Arithmetic Flag Op-
eration.

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 contain
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

DM 0000

4C59

DM 0001

1111

DM 0002

F35A

DM 1111

5555

DM 1113

2506

DM 1114

D541

5555 moved 
to LR 00.

Indicates 
DM 1111.

Indirect 
address

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 6655.

The IEMS(––) instruction can be used to change the destination of 

DM from the

DM area to one of the banks in the EM area. Refer to 5-25-15 INDIRECT EM
ADDRESSING – IEMS(––) for details.

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 giv-
en 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.