Rockwell Automation 1771-DE Absolute Encoder Module User Manual - Manual (Page 33)

Offset Programming
Chapter 5
5Ć2
In this example, the 0 machine position is “ahead” of the 0 encoder
position. Depending on which equation you use (your reference point),
the offset value is either positive or negative.
Offset Value From 0 Encoder Position and From 0 Machine Position
3584
0
0
512
Encoder
Machine shaft
At encoder position 0, machine shaft position is 512.
The offset is +3,584.
At machine shaft position 0, encoder position is 3,584.
The offset is Ć512.
13522
The equation (from 0 encoder position) is:
4,096 - 512 = 3,584
The offset is +3,584.
The equation (from 0 machine position) is:
3,584 - 4,096 = -512
The offset is -512.
You get the same result from programming either +3,584 or -512.
Once you determine the offset value, you need to program two
write-block-transfer words. These are the last two words of the write-data
block that you send to the absolute encoder module. You program them in
BCD, as you do the preset values.
Offset Words