Mitsubishi Electric Q172DCPU User Manual page 164

6 INSPECTION AND MAINTENANCE
(f) Flowchart for when "BT " displays on 7-segment LED
"BT1" or "BT1" displays when the external battery voltage of battery holder
unit is lowered.
"BT1" or "BT1" displays at the following cases.
• BT1: Battery voltage 2.7V or less
• BT2: Battery voltage 2.5V or less
The following shows the flowchart when the "BT " displays.
"BT " displays on 7-segment LED
Turn off the Multiple CPU system
power supply.
Replace the external battery.
Turn on the Multiple CPU system
power supply.
Does "BT
disappear on 7-segment
LED (Confirm ON/OFF by
monitoring SM )
REMARK
If SM51,SM58 turns on, the details of the programs, parameters, absolute position
data and latch data cannot be guaranteed.
It is recommended to back-up the battery periodically.
"
NO (SM58 or SM51 ON)
YES (SM58, SM51 OFF)
END
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H/W fault
Explain the error symptom and get
advice from out sales representative.