Indexing - Mitsubishi MELSEC Q Series Programming Manual

3.3

Indexing

(1) Overview of indexing
(a) Indexing is an indirect setting made by using an index register.
(b) Indexing with 32-bit index registers in addition to 16-bit index registers is available with
(2) Indexing with 16-bit index registers
(a) Example of indexing
(b) Devices to which indexing can be used
3-12
When an Indexing is used in a sequence program, the device to be used will become
the device number specified directly plus the contents of the index register.
For example, if D2Z2 has been specified, the specified device is calculated as
follows: D(2+3) = D5 and the content of Z2 is 3 become the specified device.
the Universal model QCPU and LCPU.
Each index register can be set between
Indexing is performed in the way shown below:
X0
MOV
X0
MOV
With the exception of the restrictions noted below, Indexing can be used with devices
used with contacts, coils, basic instructions, and application instructions.
1) Devices to which indexing can not be used
Device
E
$
.
FX, FY, FD
P
I
Z
S
TR
BL
*1: SFC transfer devices and SFC block devices are devices for SFC use.
Refer to the manual below for how to use these devices.
• MELSEC-Q / L / QnA Programming Manual (SFC)
Stores -1 at Z0.
K
1 Z0
Stores the data of D10Z0=
D10Z0 D0
D{10+(-1)} = D9 at D0.
Indexing
Meaning
Floating decimal point data
Character string data
Bit designated for word device
Function devices
Pointers used as labels
Interrupt pointers used as labels
Index register
Step relay
SFC transfer devices*1
SFC block devices*1
32768 and 32767.