Rockwell Automation 8520-ARM2 9/Series CNC AMP Reference Manual Documentation Set - Manual (Page 740)

Integrating a Linear Feedback Device
Appendix B
B-2
The feedback from the scale should produce an A quad B signal that
matches the required signature given in chapter 7 of this document.
Quadrature error should be less than 27 degrees. Scales with single--ended
inputs are not supported.
To properly configure the position loop you must identify to the control the
type of feedback device expected, and the number of feedback counts that
should be expected per unit of axis travel.
The following AMP parameters have special configurations required to
configure your linear scale. The remaining AMP parameters in chapter 7
may or may not apply to your servo setup depending on your specific
application.
Table B.A
Position Loop Parameters
AMP Parameter Description Value for Heidenhain
Distance--coded Marker*
Position Feedback
Type
Selects the type of position feedback device used. Three types of linear
scale hardware is supported. Select between A Quad B No Marker, A
Quad B One Marker, or Distance Coded Marker.
Distance--coded Marker
Lead Screw
Thread Pitch
A Quad B No or One Marker : The lead screw thread pitch defines the
distance of one electrical cycle for these feedback devices (see Counts
per Cycle above). This is necessary because there is no actual physical
marker series to define the cycle.
Distance Coded Marker:
The entered lead screw thread pitch is not
used for position loop calculations when configuring distance coded
markers.
(enter actual lead screw
thread pitch for velocity
loop)
Position Feedback
Counts/Cycle
A Quad B No or One Marker: The entered Lead Screw Thread Pitch
defines the distance of one cycle for these feedback devices. Enter the
number of feedback counts expected over the thread lead distance. For
example if you entered a one inch lead screw thread pitch you would
enter the number of counts expected from the scale over that one inch of
travel. If the number of counts expected is greater than the allowable
number of counts simply enter a smaller lead screw thread pitch. If you
are forced to enter a lead screw thread pitch other than the actual screw
pitch, you may need to compensate when configuring gear ratios for the
velocity loop.
Distance Coded Marker:
The number of feedback counts expected for
the distance equal to the entered Smaller Periodic Distance.
20,000
Smaller Period for
DCM Scales
This parameter is used for scales with distance coded markers only. The
distance coded marker supported by the 9/Series must have equally
spaced odd and even markers. The distance between every odd marker
must be the same. The distance between every even marker must be the
same. For this parameter enter the smaller of these two distances.
20 mM
B.2
Configuring the Position
Loop with Linear Feedback