Home Position Return Mode; Outline Of Home Position Return - Mitsubishi Electric MELSERVO-J4 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, check that the limit switch operates
and SIG turns on.
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.
When using an incremental encoder, make use that the Z-phase has been
passed through once before the home position return. Z-phase unpassed will
trigger [AL. 90.5 Home position return incomplete warning].
Home position return method
Deceleration starts at the external
limit front end. After the rear end is
passed, 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.
This is a typical home position return method
using an external limit.
The repeatability of the home position return is
good.
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.
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