Battery Voltage Low Detection [M8005 And M8006]; Power Failure Detection Time [D8008, M8008 And M8007]; Scan Time (Monitor) [D8010 To D8012] - Mitsubishi Electric MELSEC FX3U Programming Manual

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

37.2.3 Battery voltage low detection [M8005 and M8006]

This special device detects low voltage in the lithium battery for memory backup.
In FX /FX PLCs, the BATT (BAT) LED turns ON when the PLC detects low battery voltage.
3U 3UC
In FX PLCs, the ALM LED indicator turns ON when the PLC detects low battery voltage if the optional
3G
battery is installed and the battery mode is selected by the parameter setting.
Use the following program to notify low battery voltage to the outside.
M8005
0
Battery
voltage low

37.2.4 Power failure detection time [D8008, M8008 and M8007]

1. FX PLC (AC power supply type)
3U
The table below shows the allowable momentary power failure time in FX
Supply voltage
100V AC system
200V AC system
2. FX /FX PLC (DC power supply type)
3U 3UC
The allowable momentary power failure time in the FX
overwrite the power failure detection time in device D8008.
DC power supply
M8000:RUN monitor
M8007:Momentary
power failure
detection
M8008:Power failure
detected

37.2.5 Scan time (monitor) [D8010 to D8012]

The present value, minimum value and maximum value of the PLC scan time (operation time) are stored in
D8010, D8011 and D8012 respectively (in 0.1-ms units).
When using the constant scan mode, the values stored in these devices include the waiting time for the
constant scan time.
D8010: Present value
D8011: Minimum value
D8012: Maximum value
"Battery voltage low"
Y001
M8006 latches the battery voltage low.
Allowable momentary power
failure time
10 ms
Setting range: 10 to 100 ms
Set a value to D8008.
Default: 10 ms
Approx. 2 ms
1 scan time
D8008
Power failure detection time
5ms
The values stored in these devices can be
monitored from peripheral equipment.
37 Operation of Special Devices (M8000 -, D8000 -)
37.2 Supplement of Special Devices (M8000 - and D8000 -)
PLCs (AC power supply type).
3U
AC power supply
M8000: RUN monitor
M8007: Momentary
power failure
detection
M8008: Power failure
detected
/FX PLCs (DC power supply type) is 5 ms. Do not
3U 3UC
Approx. 5 ms
1 scan time
D8008
Power failure
detection time
10ms
911
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A
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