Types Of Backup Methods Against Power Interruption - Mitsubishi Electric MELSEC-Q Structured Programming Manual

FXCPU Structured Programming Manual
[Device & Common]
1.2.3

Types of backup methods against power interruption

There are following types of latch (backup) of the program memory and built-in devices in PLCs.
1. Battery backup method
FX /FX /FX
U 2C
Item
Latched (backed-up) contents
Maintenance
Cautions
2. Flash memory backup method
FX /FX PLCs
3U 3UC
Item
Latched (backed-up) contents
Maintenance
Cautions
3. EEPROM backup method
FX /FX /FX
0S 0N
Item
Latched (backed-up) contents
Maintenance
Cautions
4. Capacitor backup method
FX /FX PLCs
1N 1NC
Item
Latched (backed-up) contents
Maintenance
Cautions
32
/FX /FX /FX
2N 2NC 3G 3GC
A battery backs up the built-in RAM memory, latched type devices and clock data.
Periodical replacement is required.
For rough guide to the replacement frequency, refer to the User's Manual [Hardware Edition] of each
PLC.
1) When the battery voltage becomes low, sequence programs and other latched (backed-up)
contents are lost.
2) When an optional memory cassette (flash memory) is attached, it is not necessary to back up
sequence programs using the battery (in FX
1) The flash memory built in a memory cassette holds sequence programs.
2) A battery is used also to hold latched (backed-up) type devices and clock data.
Maintenance is not required.
The upper limit is set for the number of times of overwriting.
(Refer to the User's Manual [Hardware Edition] of each PLC.)
/FX /FX /FX /FX
1S 1N 1NC 3S
1) The EEPROM built in the PLC holds sequence programs and latched (backed-up) type devices.
2) A capacitor is used also to hold the clock data.
Maintenance is not required.
1) The upper limit is set for the number of times of overwriting.
(Refer to the User's Manual [Hardware Edition] of each PLC.)
2) For secure backup, it is necessary to keep the PLC power ON for 5 minutes or more, and then turn
OFF the power.
1) The large-capacity capacitor built in the PLC holds latched (backed-up) type devices and clock
data.
2) The capacitor holds data for 10 days (when the ambient temperature is 25°C) if it is fully charged
as described below.
Maintenance is not required.
1) The large-capacity capacitor is charged while the PLC is ON, and fully charged after the PLC is
ON for 30 minutes or more.
2) When the voltage of the large-capacity capacitor becomes low, latched (backed-up) type devices
are not held correctly.
When using the PLC for the first time after purchase, or when using the PLC after power OFF for a
long time (10 days [when the ambient temperature is 25°C] in the fully charged status), clear
latched (backed-up) type devices.
/FX /FX PLCs
3U 3UC
Description
Description
/FX PLCs
3G 3GC
Description
Description
1.2 Program Memory and Devices
/FX PLCs).
3U 3UC
1 Device Outline