Mitsubishi Electric MELSERVO-J4 MR-J4 TM Instruction Manual page 394

12. ABSOLUTE POSITION DETECTION SYSTEM
12. ABSOLUTE POSITION DETECTION SYSTEM
CAUTION
12.1 Summary
12.1.1 Features
For normal operation, the encoder consists of a detector designed to detect a position within one revolution
and a cumulative revolution counter designed to detect the number of revolutions.
The absolute position detection system always detects the absolute position of the machine and keeps it
battery-backed, independently of whether the controller power is on or off. Therefore, once home position
return is made at the time of machine installation, home position return is not needed when power is
switched on thereafter.
Even at a power failure or a malfunction, the system can be easily restored.
If [AL. 25 Absolute position erased] or [AL. E3 Absolute position counter warning]
has occurred, always perform home position setting again. Otherwise, it may
cause an unexpected operation.
If [AL. 25], [AL. 92], or [AL. 9F] occurs due to such as short circuit of the battery,
the MR-BAT6V1 battery can become hot. Use the MR-BAT6V1 battery with case
to prevent getting burnt.
POINT
Refer to section 11.8 for the replacement procedure of the battery.
There are two types of batteries, MR-BAT6V1SET-A and MR-BT6VCASE
available to construct the absolute position detection system.
When absolute position data is erased from the encoder, always execute home
position setting before operation. The absolute position data of the encoder will
be erased in the followings. Additionally, when the battery is used out of
specification, the absolute position data can be erased.
The encoder cable was disconnected.
The battery was replaced when the control circuit power supply was off.
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