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FX Series Programmable Controllers Devices in Detail 4
4-38
4.13 Index Registers
Device Mnemonic:
V,Z
Purpose:
To modif
y
a specified device b
y
statin
g
an offset.
Alias:
(V/ Z) Re
g
ister
Index (re
g
ister/ addressin
g
/ modifier)
Offset(s) (re
g
ister/ addressin
g
/ modifier)
Indices
Modifier
Available forms:
For 16bit data V or Z
(2 devices)
For 32bit data V and Z combined
(1 device - Z is specified)
Operation is similar to data re
g
isters.
Devices numbered in:
N/A. FX0
(S)
,FX
0N
, FX, FX
2C
there are two devices V and/ or Z.
For FX
2N(C)
there are 16 devices V0 - V7 and Z0 - Z7
Further uses:
Can be used to modif
y
the followin
g
devices under certain conditions;
X, Y, M, S, P, T, C, D, K, H, KnX, KnY, KnM, KnS
Example device usage:
The pro
g
ram shown ri
g
ht transfers data from D5V to D10Z.
If the data contained in re
g
ister V is equal to 8 and the data in re
g
ister Z is equal to 14, then:
V = 8
D5V
D5 +8 =13
Ì
D13
Z = 14
D10Z
D10 + 14 = 24
Ì
D24
Hence, the actual devices used after the modifiers V and Z have been taken into account are;
D13 and D24 and not D5 and D10 respectivel
y
.
Use of Modifiers with Applied Instruction Parameters:
• All applied instruction parameters should be re
g
arded as bein
g
able to use index re
g
is-
ters to modif
y
the operand except where stated otherwise.
Special note for FX
0
and FX
0N
users:
• Users of FX
0
and FX
0N
PLC’s should note that when hi
g
h speed counters (C235 to
C255) are used as operands in applied instructions, the
y
ma
y
not be modified with V or Z
index re
g
isters.
V Z
V Z
32 Bit
16 Bit 16 Bit