Omron CP1L CPU UNIT - 03-2009, Operation Manual

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Index Registers Section 4-11
Example This example shows how to store the PLC memory address of a word (CIO 2)
in an Index Register (IR0), use the Index Register in an instruction, and use
the auto-increment variation.
MOVR(560) 2 IR0 Stores the PLC memory address of
CIO 2 in IR0.
MOV(021) #0001 ,IR0 Writes #0001 to the PLC memory ad-
dress contained in IR0.
MOV(021) #0020 +1,IR0 Reads the content of IR0, adds 1,
and writes #0020 to that PLC memo-
ry address.
Note The PLC memory addresses are listed in the diagram above, but it isn’t nec-
essary to know the PLC memory addresses when using Index Registers.
Since some operands are treated as word data and others are treated as bit
data, the meaning of the data in an Index Register will differ depending on the
operand in which it is used.
1,2,3... 1. Word Operand:
MOVR(560)
0000 IR2
MOV(021) D0 , IR2
When the operand is treated as a word, the contents of the Index Register
are used “as is” as the PLC memory address of a word.
In this example MOVR(560) sets the PLC memory address of CIO 2 in IR2
and the MOV(021) instruction copies the contents of D0 to CIO 2.
2. Bit Operand:
MOVR(560)
000013 ,IR2
SET +5 , IR2
When the operand is treated as a bit, the leftmost 7 digits of the Index Reg-
ister specify the word address and the rightmost digit specifies the bit num-
ber. In this example, MOVR(560) sets the PLC memory address of CIO 13
(0C00D hex) in IR2. The SET instruction adds +5 from bit 13 (D hex) to this
PLC memory address, so it turns ON bit CIO 1.02.
Index Register
Initialization The Index Registers will be cleared in the following cases:
1. When the operating mode is changed from PROGRAM to RUN or MONI-
TOR mode or vice-versa
2. When the power is cycled
#0001
#0020
Regular
data area
address
I/O memory
PLC memory
address
MOVE TO REGISTER instruction
MOVR(560) 0002 IR0
Pointer