Rockwell Automation 1771-QA Stepper Positioning Assembly User Manual - Manual (Page 38)

3–16 Programming and Operation
Publication 1771-UM002A–EN–P – May 2000
Move Preset
The move preset can be used to adjust the starting point value of any
move in a moveset whenever necessary. For example, the move
preset can extend one or more moves of the profile beyond the
999,999 pulse limit of the stepper controller module.
The move preset is enabled by bit 00 in the single move control word
(see section titled “Move Block”). When this bit is set, the position
register of the stepper controller module and the starting point value
of the move block will become the value stored in the preset words.
The final position value of the move block and all subsequent move
blocks will be referenced to this new starting point value.
If a move profile extends beyond 999,999 pulses and the application
calls for a return to the home position, it may be necessary to change
the preset value and again set the move preset bit (Figure 3.11).
When necessary, this must be done before the move to home position
is started. Reverse travel to the home position can require two
moves if the total travel exceeds 999,999 pulses.
Figure 3.11
Move Preset
Rate
Forward
Rate
Reverse
0
Move Preset
999,999 (to return)
999k
10524
Position
Move Preset
000,000
0