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Figure 45:
NOTE
If Rotary Rollover is active, an Absolute Index will take the shortest path to the specified index position.
6.3.2
Incremental Index
An Incremental Index is used to make the motor travel a specified distance each time the index is initiated. The final position after the
Index is completed is entirely dependant on the starting position before the Index was initiated.
If an Incremental Index is initiated a second time, it will move the same distance each time.
Figures 46 and 47 show examples of an Incremental Index profile.
Figure 46:
Figure 47:
6.3.3
Correction Index
A Correction index is intended to continuously run on the second profile correcting any position drift. It will adjust the motor position
based on changes to it's index.#.dist parameter. The Correction indexes use incremental distance values. Updates to the index
distance while the correction index is executing will take effect immediately by recalculating the index on the fly. Another words, if
this index is in progress and the distance value is changed, the move profile instantaneously recalculates based on the index's
current position, speed and acceleration. Once the Correction index is initiated it will remain active until stopped by the user with the
Profile.#.MotionStop function.
Example:
Correction index distance sources are user program calculations, fieldbus inputs or analog input values. The index distance value
can be updated via Fieldbus, by simply writing to the index distance parameter. If the analog input's Destination Variable is set to
the Index.#.Dist parameter, the index's distance value will be updated by the Analog Input. This can be set to a automatic refresh
using the Analog Input view
6.3.4
Posn Tracker Cont Index and Posn Tracker Once Index
Posn Tracker Cont and Posn Tracker Once are indexes which expect their position values to be dynamically changed while
executing. Position Tracker indexes use absolute position values. Posn Tracker Cont index once initiated, will remain active until
stopped by the user with the Profile.#.MotionStop function. The Posn Tracker Once index will accept position changes until the target
position is reached, at which point the index is complete.
The index 's position value can be updated via fieldbus, by simply writing to the index position parameter. Posn Tracker Indexes are
used to follow dynamic changes to the end point of the index prior to and during the index motion. If the analog input's Destination is
set to an Index.#.distance, the index's position value will be updated by the Analog to Position scaling found in the Analog Input view.
Posn Tracker also accepts on the fly changes to index velocity, acceleration and deceleration. The index is recalculated on the next
trajectory update.
6.3.5
Registration Index
A Registration Index functions much the same as a Home profile. The index runs at a specified velocity until a registration signal
activates. Once the signal activates, the index either beings to decelerate immediately, or it continues at velocity for a specified offset
distance.
Registration to Sensor
In a Registration Index with Sensor defined as the registration signal, the index travels at velocity until an external sensor or switch
activates. The sensor or switch must be wired to a digital input on EZMotion, Unidrive SP/Digitax ST drive, or any SM I/O module. To
38
-4
-2
-1
Starting Position: 3 Revs
Index Position: 2 Revs
Absolute Index Profile (Example 2)
1
2
3
Starting Position: 2 Revs
Index Distance: 4 Revs
Incremental Index Profile
1
2
4
Starting Position: 2 Revs
Index Distance: 3 Revs
Incremental Index - Repeated 3 Times
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0
1
2
4
5
6
7
6
8
10
12
Position
4
(Revs)
Position
8
(Revs)
Position
14
(Revs)
EZMotion User/Programming Guide
Revision: A8
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