Rockwell Automation 1440-VLF02-01RA XM-121 Absolute Shaft Module - Manual (Page 60)

Publication GMSI10-UM014D-EN-P - May 2010
52 Configuration Parameters
Speed Measurement Parameter
Use the speed measurement parameter to configure the filtering performed on
the speed measurement.
Tachometer Parameters The tachometer parameters define the characteristics of the tachometer and
determine the signal processing that will be performed on the tachometer
signal.
Q Enter the Q value for the Q filter. Q is the measure of
the sharpness of a filter Enter a value from 1 to 200 Hz.
Note: This value is used only when Q
is selected as the tracking filter type.
Important: The tracking filter
bandwidth in Constant Q mode is
limited between 0.5 and 15 Hz.
Vector Measurement Parameters
Parameter Name Description Values/Comments
Speed Measurement Parameter
Parameter Name Description Values/Comments
Exponential Averaging Time
Constant Sets the 3-dB bandwidth for the digital filter used to
calculate the Speed Value and Acceleration
Measured Value. The 3-dB bandwidth is roughly
equal to 1 / (2
π
x Exponential Averaging Time
Constant). The greater the value entered, the longer
the response of the measured Speed Value and
Acceleration Measured Value to a change in the
input signal (less sensitive to noise in the signal).
See example table below.
Time Constant
(milliseconds) -3dB Frequency
(Hz)
Settling Time
(milliseconds)
5 31.8310 11
10 15.9155 22
20 7.9577 44
50 3.1831 110
100 1.5915 220
1200 0.1326 2640