Omron CJ - PROGRAMMING MANUAL 08-2008 Programming Manual page 320

Index Registers
Instruction A m
Instruction A m+1
Instruction A m+n
282
Variation
Indirect addressing with DR offset
Indirect addressing with auto-increment
Indirect addressing with auto-decrement
Instructions That Directly Address Index Registers
Index registers can be directly addressed by the following instructions.
DOUBLE SIGNED BINARY ADD WITHOUT CARRY: +L(401), DOUBLE
SIGNED BINARY SUBTRACT WITHOUT CARRY: –L(411), DOUBLE
INCREMENT BINARY: ++L(591), and DOUBLE DECREMENT BINARY: – –
L(593)
Example 1
The following example shows how an Index Register in a program loop can
replace a long series of instructions. In this case, instruction A is repeated n+1
times to perform some operation such as reading and comparing a table of
values.
Example 2
The data in D00000 to D00099 (augend data) is added to the data in D00100
to D00199 (addend data) and the addition results are output to D00200 to
D00299. The operands of a single addition instruction are specified by index
registers and the addition operations are performed by incrementing the index
registers and repeatedly executing the addition instruction.
MOVR(560) sets the PLC memory addresses of D00000, D00100, and D00200
in index registers IR0, IR1, and IR2.
The augend data (indirectly addressed by IR0+) is added to the addend data
(indirectly addressed by IR1+) with the SIGNED BINARY ADD WITHOUT
CARRY instruction (+(400)) and the result is output to the word indirectly
addressed by IR2+. Index registers IR0, IR1, and IR2 are automatically
incremented after being referenced in the +(400) instruction.
DR@,IR@
Increment by 1: ,IR@+
Increment by 2: ,IR@++
Decrement by 1: ,–IR@
Decrement by 2: ,– –IR@
Stores the PLC memory
MOVR(560) m IR0
address of m in IR0.
Instruction A ,IR0+
Section 6-2
Syntax
Repeats the process
in a loop such as
FOR-NEXT.
Repeated 100 times.