Mitsubishi Electric Melsec-Q172DCPU User Manual page 215

6 INSPECTION AND MAINTENANCE
(h) Flowchart for when "BT " displays on 7-segment LED
"BT1" or "BT2" displays when the battery voltage is lowered.
"BT1" or "BT2" displays at the following cases.
• BT1: Battery voltage 2.7V or less
• BT2: Battery voltage 2.5V or less
The following shows the flowchart for when "BT1" or "BT2" displays on
7-segment LED.
"BT " displays on 7-segment LED
Replace the battery.
(Refer to Section 6.5.2)
Does "BT
disappear on 7-segment
LED? (Confirm ON/OFF by
monitoring SM )
REMARK
If SM51, SM58 turns on, the contents of the programs, parameters, motion device(#),
latch range device and absolute position data cannot be guaranteed.
It is recommended to back-up the data periodically.
"
NO (SM58 or SM51 ON)
YES (SM58, SM51 OFF)
END
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A hardware fault
Explain the error symptom and get
advice from our sales representative.