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51
REFERENCE 5
H
OMING
AN
AMCI N
ETWORKED
D
RIVER
Definition of Home Position
The Home Position is any position on your machine that you can sense and stop at. Once at the Home Posi-
tion, the motor position register of a Networked Driver must be set to an appropriate value. If you use the
unit’s
CW/CCW Find Home
commands, the motor position register will automatically be set to zero once the
home position is reached.
The Encoder Position register will also be reset to zero if the encoder is available
and enabled.
Defining a Home Position is completely optional. Some applications, such as those that use a
Networked Driver for speed control, don’t require position data at all.
With the exception of Absolute Moves, a Networked Driver can still perform all of its move commands if the
Home Position is not defined.
Position Preset
One of the ways to define the Home Position is to issue the Preset Position command to the Networked
Driver. When a Networked Driver is configured to use an incremental encoder, the motor position and the
encoder position are preset separately. The motor and encoder position values can be preset anywhere in the
range of –8,388,607 to +8,388,607.
CW/CCW Find Home Commands
The other choice is to use the driver’s Find Home commands to order the Networked Driver to find the Home
Position based on sensors brought into the unit. The CW Find Home command begins searching by rotating
the motor shaft in the positive direction and ends when the home sensor triggers while the Networked Driver
is rotating in the positive direction at the starting speed. The CCW Find Home command operates in the same
way but starts and ends with motion in the negative direction.
Homing Inputs
Up to three physical inputs can be used to home the driver. A Backplane Proximity bit is available in the net-
work output data that can be used to control when the home input is acted upon. This is typically used in
applications where the home input triggers multiple times in a machine cycle, and the system needs to control
which trigger is acted upon.
Physical Inputs
Home Input:
This input is used to define the actual home position of the machine.
CW Limit Switch Input:
This input is used to prevent overtravel in the clockwise direction.
CCW Limit Switch Input:
This input is used to prevent overtravel in the counter-clockwise direction.
Backplane Inputs
Backplace_Proximity_Bit:
A Networked Driver can be configured to ignore changes on the physical
homing input until the Backplace_Proximity_Bit makes a 0
1 transition. The Networked Driver will
home on the next inactive-to-active change on the physical input once this transition occurs. You must
program your host to control the state of this bit.
This bit is disabled by default, and must be activated when you configure the Networked
Driver before is can be used. If you decide to activate this bit when you configure the unit and
then never set it to a “1”, the Networked Driver will never act on the physical Home Input.
This chapter explains the various ways of homing a Networked Driver. Inputs used
to home the unit are introduced and diagrams that show how the unit responds to
a homing command are given.
