Emerson FM-3 manual Incremental Indexes

Operational Overview

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.

Incremental Index

Incremental Index

Start Position = 1 Rev

Index Distance = 2 Revs

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 FM-3 module 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. The example below shows this operation.

Incremental Index

Start Position = 1 Rev

Index Distance = 2 Revs

Figure 26: Incremental Index Example 2

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