Rockwell Automation 20D PowerFlex 700S AC Drives with Phase II Control Reference Manual - Manual (Page 101)

Rockwell Automation Publication PFLEX-RM003E-EN-E - January 2011 101
Detailed Drive Operation Chapter 1
Absolute Point to Point Positioning:
The Point to Point positioning mode may be configured to operate in an absolute
mode. The absolute mode allows the point to point position regulator to remain
active at all times, even when the drive is stopped and restarted. An absolute
feedback device such as a Stegmann Hi-Resolution encoder can also be used in
absolute mode in order to retain position feedback during power loss. Stegmann
Hi-Resolution encoders provide absolute position feedback for up to 4096 motor
revolutions.
To enable absolute mode, set parameter 740 [Position Control], bit 6
“AbsPositCtrl” = 1.
To define zero position, position the motor shaft to where you would like zero
position to be. Set parameter 740 [Position Control], bit 9 “SetZeroPosit” = 1.
This setting redefines where the zero position of the motor shaft will be. Then set
parameter 740 [Position Control], bit 9 “SetZeroPosit” = 0.
Parameters 745 [PositRef EGR Mul] and 746 [PositRef EGR Div] are not used
in absolute mode. Therefore, the position reference is always scaled to feedback
counts in absolute mode.
Example to Control the Point to Point Position with Digital Inputs:
Digital Inputs can be used to control up to 16 positions for the point to point
loop by using the
Bit Swap and Selector Switches user functions.
This example is used to control the selector switch function block to select 4
different positions from digital inputs 4 and 5 (note that we can select up to 16
positions with the selector switch, but this example only uses 4). Once the desired
position is selected, digital input 3 is used to pass the chosen position through the
switch to parameter 758 [Pt-Pt Posit Ref ].
ATTENTION: When absolute mode is on, if the motor shaft is moved
while the drive is stopped or powered down, the drive will move to the
position reference set in parameter 758 [Pt-Pt Posit Ref] when started. For
applications where the motor shaft should not move on the initial start,
load the value from parameter 763 [Position Actual] into parameter 758
[Pt-Pt Posit Ref] before starting the drive.