Using Intelligent Input Terminals
Oper
ations
a
nd Moni
tor
ing
4–40
Zero-Return
Functions
A
zero-return
operation (also called a
home-return
) occurs when the motor moves the load to a
particular starting position. Using parameter P068, you may select one of three possible types
of zero-return operations. Parameter P069 selects the search direction. The
zero pulse input
(also called
zone input
) signals the arrival at the zero position.
It is generally a requirement (or good practice) to perform a zero-return operation after every
powerup of the inverter. It is possible that the previous power OFF occurred when the load was
not at zero position. Or, it may be that an external force moved the load during the power OFF
period. If you do not perform a zero-return operation after power ON, then the inverter uses the
current position at powerup as the zero position.
The three available zero-return modes differ in the overall search speed, final approach
direction to the origin, and the limit switch input transition (or encoder pulse, if used) causing
the final stop. Choose the zero-return mode that best fits your application.
Low-speed Zero Return:
1.
Motor accelerates for the specified
acceleration time to the low zero-
return speed
2.
Motor runs at the low zero-return
speed
3.
Inverter stops motor and sets position
value to zero when [ORL] signal
turns ON
High-speed 1 Zero Return:
1.
Motor accelerates for specified
acceleration time to high zero-return
speed
2.
Motor runs at high zero-return speed
3.
Motor starts deceleration when
[ORL] signal turns ON
4.
Motor runs in reverse direction at
low-speed zero-return speed
5.
Inverter stops motor and sets
position value to zero when [ORL]
signal turns OFF
Opt. Code
and
Symbol
69=[ORL]
70=[ORG]
Valid for
Inputs
[1] to [8]
Required
Settings
P068, P069,
P070, P071
Default
terminal
Requires
config.
Code
Function
Data
Description
P068
Zero-return mode selection
00
Low speed
01
High speed 1
02
High speed 2
P069
Zero return direction selection
00
Forward
01
Reverse
Zero-return limit
[ORL]
Zero-return trigger
[ORG]
Encoder Z pulses
[Z]
Inverter
Output to motor
Output
frequency
[ORG]
Position
0
Low-speed zero-return level
P070
[ORL]
Origin
1
2
Output
frequency
[ORG]
Position
0
High zero-return level
P071
[ORL]
Origin
1
2
3
4
P070 Low-speed zero-
return level
5
