Omron CP1H CPU

173
Index Registers Section 4-15
tions shown in the following table. Use these instructions to operate on the
Index Registers as pointers.
The Index Registers cannot be directly addressed in any other instructions,
although they can usually be used for indirect addressing.
The SRCH(181), MAX(182), and MIN(183) instructions can output the PLC
memory address of the word with the desired value (search value, maximum,
or minimum) to IR0. In this case, IR0 can be used in later instructions to
access the contents of that word.
4-15-1 Using Index Registers
Processing of multiple (identical) instructions such as consecutive addresses
for table data can be merged into one instruction by combining repetitive pro-
cessing (e.g., FOR(513) and NEXT(514)instructions) with indirect addressing
using Index Registers, thereby simplifying programming.
The Index operation uses the following procedure.
1. PLC memory addresses for the addresses in the Index Registers are
stored using a MOVR instruction.
2. Operation is then executed by indirectly addressing Index Registers to the
operand for Instruction A.
3. The addresses are moved using processing such as adding, subtracting,
incrementing, or decrementing the Index Register (see note).
Instruction group Instruction name Mnemonic
Data Movement
Instructions
MOVE TO REGISTER MOVR(560)
MOVE TIMER/COUNTER PV TO REG-
ISTER
MOVRW(561)
DOUBLE MOVE MOVL(498)
DOUBLE DATA EXCHANGE XCGL(562)
Table Data Processing
Instructions
SET RECORD LOCATION SETR(635)
GET RECORD NUMBER GETR(636)
Increment/Decrement
Instructions
DOUBLE INCREMENT BINARY ++L(591)
DOUBLE DECREMENT BINARY – –L(593)
Comparison Instructions DOUBLE EQUAL =L(301)
DOUBLE NOT EQUAL < >L(306)
DOUBLE LESS THAN < L(311)
DOUBLE LESS THAN OR EQUAL < =L(316)
DOUBLE GREATER THAN > L(321)
DOUBLE GREATER THAN OR EQUAL > =L(326)
DOUBLE COMPARE CMPL(060)
Symbol Math Instructions DOUBLE SIGNED BINARY ADD WITH-
OUT CARRY
+L(401)
DOUBLE SIGNED BINARY SUBTRACT
WITHOUT CARRY
–L(411)
IR0
,IR0
Instruction execution
repeatedly incrementing
IR0 by 1
Instruction
Indirect
addressing
Table data