Types Of Backup Methods Against Power Failure; Change Between General Devices And Latched (Battery Backed) Devices; How To Initialize Devices (Battery Backed) - Mitsubishi FX3U Series Programming Manual

FX /FX Series Programmable Controllers
3U 3UC
Programming Manual - Basic & Applied Instruction Edition
2.6.3

Types of backup methods against power failure

There are following types of latch (battery backup) for the program memory and built-in devices in the PLC.
1. Battery backup method
Item
Latched (battery
backed) contents
Maintenance
Cautions
2. Flash memory backup method
Item
Latched (battery
backed) contents
Maintenance
Cautions
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 FX /FX
3U 3UC
devices by the parameter settings described later.
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 FX /FX
3U 3UC
the parameter settings described later.
2.6.5

How to initialize devices (battery backed)

1. ZRST (FNC 40) instruction (zone reset)
By ZRST (FNC 40) instruction, devices in a specified range can be cleared at one time.
Command
input
FNC 40
ZRST
2. M8032 (latch memory all clear)
When M8032 is turned ON, all latched (battery backed) type devices are cleared.
36
A lithium battery backs up the RAM memory, devices (battery backed) and clock data built in the PLC.
Periodic replacement of the battery once in four or five years.
1) When the battery life is expired, sequence programs and other latched (battery backed) contents
are lost.
2) When an optional memory cassette (flash memory) is mounted, it is not necessary to back up
sequence programs by the battery.
1) The flash memory built into the memory cassette backs up sequence programs.
2) A battery is required to back up latched (battery backed) devices and clock data from failure.
Maintenance is not necessary.
The upper limit is set to the number of times for overwriting.
(Refer to the Hardware Manual of the main unit.)
PLCs, some latched (battery backed) type devices can be changed into non-latch type
PLCs, non-latch type devices can be changed into latched (battery backed) type devices by
D D
1 2 Devices
→ For the details of ZRST (FNC 40) instruction, refer to Section 12.1.
→ In addition to ZRST instruction, FMOV (FNC 16) instruction is available also.
For the details of FMOV (FNC 16) instruction, refer to Section 9.7.
2.6 Program Memory and Devices (Battery Backed)
Description
Description
D D
1 through 2 are reset at one time.
→ For the details, refer to Subsection 36.2.11.
2 Overview (Sequence Program)