Home Position Return Mode; Outline Of Home Position Return - Mitsubishi Electric MELSERVO-J4 Series Instruction Manual

6. HOW TO USE INDEXER

6.4 Home position return mode

6.4.1 Outline of home position return

A home position return is performed to match the command coordinates with the machine coordinates.
Under the incremental method, each power-on of the input power supply requires the home position return.
Contrastingly, in the absolute position detection system, once you have performed the home position return
at machine installation, the current position will be retained even if the power supply is shut off. Therefore,
the home position return is unnecessary when the power supply is switched on again.
This section shows the home position return methods of the servo amplifier. Select the optimum method
according to the configuration and uses of the machine.
(1) Home position return types
Select the optimum home position return type according to the machine type or others.
System
Torque limit changing dog
type
Torque limit changing data
set type
POINT
Before performing the home position return, make sure that the limit switch
operates.
Check the home position return direction. An incorrect setting will cause a
reverse running.
Check the input polarity of the external limit. Otherwise, it may cause an
unexpected operation.
In the following cases, make sure that the Z-phase has been passed through
once before performing a home position return.
When a servo amplifier is used in the DD motor control mode
Z-phase unpassed will trigger [AL. 90.5 Home position return incomplete
warning].
For precautions for using linear servo motors or fully closed loop system, refer to
section 4.4.15 and 4.4.16.
Home position return method
Deceleration starts at the external
limit detection. The position specified
by the first Z-phase signal, or the
position of the first Z-phase signal
shifted by the home position shift
distance is used as the home
position.
An arbitrary position is used as the
home position.
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Feature
This is a typical home position return method
using an external limit.
The repeatability of the home position return is
high.
The machine is less loaded.
Used when the width of the external limit can be
set equal to or greater than the deceleration
distance of the servo motor.
An external limit is not required.