Mitsubishi Electronics FX3G

FX3G/FX3U/FX3UC Series Programmable Controllers

Programming Manual - Basic & Applied Instruction Edition

2 Overview (Sequence Program)

2.6 Program Memory and Devices

Introduction

Overview

Instruction

List

Devices

in Detail

Specified the

Device &

Constant

Before

Programming

Basic

Instruction

FNC00-FNC09

Program Flow

FNC10-FNC19

Move & Compare

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 FX3G 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 FX3G 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 FX3U/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