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FX3G/FX3U/FX3UC Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
2 Overview (Sequence Program)
2.6 Program Memory and Devices
1
Introduction
2
Overview
3
Instruction
List
4
Devices
in Detail
5
Specified the
Device &
Constant
6
Before
Programming
7
Basic
Instruction
8
FNC00-FNC09
Program Flow
9
FNC10-FNC19
Move & Compare
10
FNC20-FNC29
Arith. & Logic
Operation
2.6.4 Change between general devices and latched (battery backed) devices
1. When using latched (battery backed) type devices as non-latch type devices
In FX3U/FX3UC PLCs, some latched (battery backed) type devices can be changed into non-latch type devices by the
parameter settings.
Devices dedicated to latched type cannot be changed into non-latch type devices even by the parameter settings.
Such devices can be handled as non-latch type devices by clearing all latched (battery backed) type devices by the
initial pulse (M8002) in a program.
2. When using non-latch type devices as latched (battery backed) type devices
In FX3U/FX3UC PLCs, non-latch type devices can be changed into latched (battery backed) type devices by the
parameter settings.
In FX
3G PLCs, non-latched type devices can be changed to latched (battery backed) type devices when the optional
battery is installed and the battery mode is selected in the parameter setting.
2.6.5 How to initialize devices (battery backed)
Latched type devices can be initialized by clearing the entire PLC memory using peripheral equipment, clearing all
latched memory using the special auxiliary relay M8032, or executing the ZRST instruction.
This subsection describes two major methods.
1. M8032 (latch memory all clear)
When M8032 is turned ON, all latched type devices
*1
(including reset coils of timers and counters) are cleared.
M8032 can be turned ON and OFF using the forced ON/OFF operation from peripheral equipment or within the
sequence program. Note that latched type devices cannot be turned ON while M8032 is ON.
When turning ON M8032 within the sequence program, note that latched type devices are cleared during END
processing after M8032 is turned ON.
Program example: This program clears all latched type devices.
→ For details, refer to Subsection 37.2.11.
*1. Includes general type devices in FX
3G PLCs whose type is changed to the latched (battery backed) type when
the optional battery is installed.
2. ZRST (FNC 40) instruction (zone reset)
The ZRST instruction can clear multiple devices all at once.
(Because only a limited device range can be specified for the ZRST instruction, only a part of the latched type devices
can be cleared at a time.)
Program example: This program clears latched (battery backed) type devices in the ranges shown in the table below
in FX
3U/FX3UC PLCs.
→ For details on the ZRST (FNC 40) instruction, refer to Section 12.1.
→ For details on latched type devices, refer to Subsection 2.6.2 and Chapter 4.
Latched (battery backed) type device range
Auxiliary relay M500~M7679
State S500~S4095
Timer T246~T255
Counter
C100~C199,
C220~C255
Data register D200~D7999
M8002
Initial pulse
M8032
Clear input
M500
FNC 40
ZRST
M7679
S500
FNC 40
ZRST
S4095
T246
FNC 40
ZRST
T255
C100
FNC 40
ZRST
C199
C220
FNC 40
ZRST
C255
D200
FNC 40
ZRST
D7999