Rockwell Automation 8520-ARM2 9/Series CNC AMP Reference Manual Documentation Set - Manual (Page 211)

Servo Parameters
Chapter 7
7-65
If not, an error will occur upon powering up the control after downloading
AMP.
This parameter must be set independently for each axis.
Function
Important: The standard servo feedback configuration uses one feedback
device for both positioning and velocity data. If this is the case on your
system, this parameter must be set to the same value as the parameter
Position Feedback Counts/Cycle. Refer to this chapter’s overview for an
example of a system that uses two feedback devices for the same axis and
may require a different value be selected here.
Important: Though the analog servo interface does not support a separate
feedback device for the velocity loop, you must still configure these
velocity loop parameters including Velocity Loop Feedback Port,
Velocity Loop Feedback Type, Velocity Feedback Counts/Cycle, and
Sign of Velocity Feedback. These parameters must be set to the same
values as their positioning loop counterparts.
Velocity Feedback Counts/Cycle specifies the number of counts that are
produced by the velocity encoder for each electrical cycle (usually the
same number of counts as set with the parameter Position Feedback
Counts/Cycle as they are typically the same encoder). For encoders with
one marker, an electrical cycle is one revolution. For encoders with two
markers, an electrical cycle is one half revolution.
Important: Spindle encoders must have only one marker per revolution.
Encoders are generally labeled with the number of lines they have per
electrical cycle. Since encoders used with the control must have two
feedback channels (A and B) positioned in quadrature, the number of
counts produced is actually 4 times the number of lines.
Velocity Feedback Counts/Cycle = counts/elec. cycle = 4 x lines/elec.
cycle
Axis Parameter
Number
Axis Parameter
Number
(1) [1565] (7) [7565]
(2) [2565] (8) [8565]
(3) [3565] (9) [9565]
(4) [4565] (10) [10565]
(5) [5565] (11) [11565]
(6) [6565] (12) [12565]
7.3.3
Velocity Feedback
Counts/Cycle