LOGIX-UM002A-EN-P, Motion Modules in Logix5000 Control ...

D-10 Axis Attributes
Attribute Axis Type Data Type Access Description
Aux Feedback
Interpolation
Factor
Aux Feedback
Noise Fault
AXIS_SERVO_DRIVE DINT GSV Feedback Counts per Cycle
Publication LOGIX-UM002A-EN-P - February 2006
The Feedback Interpolation attributes establish how many Feedback
Counts there are in one Feedback Cycle. The Feedback Interpolation
Factor depends on both the feedback device and the drive feedback
circuitry. Quadrature encoder feedback devices and the associated drive
feedback interface typically support 4x interpolation, so the Interpolation
Factor for these devices would be set to 4 Feedback Counts per Cycle
(Cycles are sometimes called Lines). High Resolution Sin/Cosine
feedback device types can have interpolation factors as high as 2048
Counts per Cycle. The product of the Feedback Resolution and the
corresponding Feedback Interpolation Factor is the overall resolution of
the feedback channel in Feedback Counts per Feedback Unit. In our
example, a Quadrature encoder with a 2000 line/rev resolution and 4x
interpolation factor would have an overall resolution of 8000 counts/rev.
AXIS_SERVO_DRIVE BOOL Tag Set when there is noise on the feedback device’s signal lines.
• For example, simultaneous transitions of the feedback A and B
channels of an A Quad B is referred to generally as feedback
noise.
• Feedback noise (shown below) is most often caused by loss of
quadrature in the feedback device itself or radiated
common-mode noise signals being picked up by the feedback
device wiring. You can see both of these on an oscilloscope.
• To troubleshoot the loss of channel quadrature, look for:
• physical misalignment of the feedback transducer
components
• excessive capacitance (or other delays) on the encoder
signals
• Proper grounding and shielding usually cures radiated noise
problems.
The controller latches this fault. Use a Motion Axis Fault Reset (MAFR)
or Motion Axis Shutdown Reset (MASR) instruction to clear the fault.