Index; Absolute Index - Emerson EZMotion User Manual

Figure 42:
Go Forward To Next Sensor
On some machines, motion in a certain direction may be prohibited due to mechanical design. In this case, the Back Off
Before Homing option may not be practical. In this case, if the Home Sensor is active when the Home is initiated, the motor
continues in the programmed direction until the next "Rising Edge" of the external home sensor is detected. Figure 43 shows
the Home to Sensor profile when the Home Sensor is active when home is initiated and Go Forward To Next Sensor is
selected.
Figure 43:
6.3

Index

An Index profile is used to move the motor a precise distance or to a specific position. There are many different applications
that can be solved using different combinations of Index types. The five major types of Indexes are Absolute, Incremental,
Registration, Rotary Plus, and Rotary Minus. Each of these Index types are described in detail below.
6.3.1

Absolute Index

An Absolute Index is used to move the motor to a specific position. After completing an Absolute Index, the motor will always
be in the same position regardless of the starting position of the motor. The direction that the motor moves during an Absolute
Index is dependant upon its position when the index is initiated.
If an Absolute Index is initiated a second time, just after completing the first index the motor will not move because it is already
at its specified absolute position.
Figures 44 and 45 show examples of an Absolute Index profile.
Figure 44:
EZMotion User/Programming Guide
Revision A8
+ Velocity
Home Sensor is active when
Home is initiated, so motor
travels in negative direction
Home Accel
Home Velocity
-
Home Initiate
External Home Sensor
Home to Sensor (Back Off Before Homing)
Velocity
Home Accel
Home Initiate
External Home Sensor
First rising edge is used as Home reference
Home to Sensor (Go Forward To Next Sensor)
-4 -2 -1
Starting Position: -2 Revs
Index Position: 2 Revs
Absolute Index Profile (Example 1)
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Home Velocity
Home Decel
Home Accel
Home Decel
External Home
Sensor Clears
Home Velocity
Home Decel
0 1 2
Time
Time
Position
4
(Revs)
37