Control Techniques Epsilon EP-P, Reference Manual

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Epsilon EP-P Drive Reference Manual
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www.controltechniques.com Revision: A4
Absolute Indexes
Absolute indexes are used in applications where the motor must travel to a specific position, regardless of where the motor is when the index
is initiated.
The drive calculates the distance required to move to the specified position from the current position.
Figure 23: Absolute Index Example 1
In the example above, the current position is 1 rev. If this index is initiated, the motor will travel to a position of 5 revs no matter where it is
sitting before the move. From 3 revs, it will travel 2 revs to finish at 5 revs. If the absolute index to 5 revs is initiated a second time immediately
after the index, no motion will occur because the motor will already be at a position of 5 revs.
The direction of an Absolute Index is determined by the starting position and the absolute index position. If the starting position for the above
index is 9 revs, then the motor will rotate in the negative direction to end up at 5 revs. The figure below shows this.
Figure 24: Absolute Index Example 2
Absolute indexes with Rotary Rollover enabled will take the shortest path to the position entered in the index position parameter.
NOTE
Absolute indexes move to positions relative to where the machine was homed using the Home, or the DefineHome destination.
Incremental Indexes
An incremental index will move the motor a specified distance in the + or - direction regardless of the starting position. The direction of the
incremental index motion is determined by the sign (+ or -) of the Index Distance parameter.
Figure 25: Incremental Index Example
In the example above, the motor starts at 1 rev, travels a distance of 2 revs and stops at 3 revs. If the same index is initiated a second time, the
drive would move the motor another 2 revs to a position of 5 revs. If initiated a third time, the motor would travel another 2 revs to a final
position of 7 revs. Figure 26 shows this operation.
Absolute Index
Start Position = 1 Rev
Index Position = 5 Revs
Absolute Index
Start Position = 9 Revs
Index Position = 5 Revs
Incremental Index
Start Position = 1 Rev
Index Distance = 2 Revs