Mitsubishi Electric MELSEC FX3U Programming Manual page 35

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
6. Data registers (D)
Data registers store numeric data values.
All data registers in FX PLCs are 16-bit type
(whose most significant bit is positive or
negative). When two consecutive registers are
combined, they can handle 32-bit numeric value
(whose most significant bit is positive or
negative).
(For the numeric value range, refer to "Counter"
on the previous page.)
In the same way as other devices, data registers
are classified into general type and latched type
(battery backed).
7. Extension registers (R) and extension file
registers (ER)
Extension registers (R) are the extended form of
data registers (D). They are protected by the
battery against power failure in FX
PLCs.
In FX PLCs, general type devices can be
3G
protected against power failure when the optional
battery is connected.
In FX /FX /FX
3G 3U
extension registers (R) can be stored in
extension file registers (ER).
In FX /FX
3U 3UC
(ER) can be used only while a memory cassette
is mounted.
8. Index registers (V)(Z)
Among registers, there are index type registers V
and Z used for modification.
A data register V or Z is added to another device
as follows:
[In the case of "V0, Z0 = 5"]
D100V0 = D105, C20Z0 = C25 ← Device
number + V or Z
Data registers and index registers are used for
indirectly specifying the set value of timers and
counters, or used in applied instructions.
9. Pointers (P)(I)
Pointers are classified into branch pointers and
interrupt pointers.
• A branch pointer (P) specifies the jump
destination of the conditional jump CJ (FNC
00) or the call subroutine CALL (FNC 01)
instruction.
• An interrupt pointer (I) specifies the routine of
an input interrupt, timer interrupt or counter
interrupt.
→ Refer to Section 4.9.
→ Refer to Section 4.10.
/FX
3U
PLCs, the contents of
3UC
PLCs, extension file registers
→ Refer to Section 4.11.
value
→ Refer to Section 4.12.
2.5 Introduction of Devices Constructing PLC
10.Constants (K)(H)(E)
Constant numerical values used in the PLC, "K"
indicates a decimal integer value, "H" indicates a
hexadecimal value, and "E" indicates a real
number (floating point data).
Constants are used as set values or present
values of timers and counters, or operands for
applied instructions.
3UC
2 Overview (Sequence Program)
→ Refer to Chapter 5.
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