Rockwell Automation 20D PowerFlex 700S AC Drives with Phase II Control Reference Manual - Manual (Page 99)

Rockwell Automation Publication PFLEX-RM003E-EN-E - January 2011 99
Detailed Drive Operation Chapter 1
of feedback because it is added to the position reference after the EGR scaling.
Offsets must be maintained to keep the position. For example, if you enter 300 in
the offset, the position loop will move 300 counts extra. If you zero the offset
command, the motor will return to the previous position. When it is necessary to
zero the offset after a move without returning to the previous position, set
parameter 740 [Position Control], bit 5 “X Off ReRef ” = 1. Then set the offset
value = 0. Then set [Position Control,] bit 5 “X Off ReRef ” = 0. The system will
not make an offset move when bit 5 of [Position Control] is set.
Point to Point Acceleration and Deceleration
Parameter 759 [Pt-Pt Accel Time] sets the acceleration time in seconds from zero
to base motor speed.
Parameter 760 [Pt-Pt Decel Time] sets the deceleration time in seconds from
base motor speed to zero.
The [Pt-Pt Accel Time] and [Pt-Pt Decel Time] are only active in Point to Point
mode. The Default = 10 seconds.
Position Loop Output Limits
Parameter 775 [XReg Spd LoLim] sets the negative speed limit at which the
position regulator will output. The default is set to -10% of the base motor speed.
Set this to the negative speed at which you want the drive to run for point to
point moves.
Parameter 776 [XReg Spd HiLim] sets the positive speed limit at which the
position regulator will output. The default is set to +10% of the base motor
speed. Set this to the positive speed at which you want the drive to run for point
to point moves.
Tuning Tips
The speed regulator of the drive must be tuned prior to tuning the Position Loop.
Refer to
Speed PI Regulator on page 152 of this manual for tips on tuning the
speed regulator.
Do not attempt to set the accel/decel rates of the point to point position loop
faster than can be accomplished by the system. Attempting to set the accel/decel
rates faster than the system can handle will cause instability in the position loop.
Do not attempt to operate beyond the torque limits of the drive motor
combination.