Allen-Bradley 1440-SDM02-01RA, User Manual, Page: 74 / 168

74 Rockwell Automation Publication 1440-UM001D-EN-P - September 2016
Chapter 2 Configure the XM-124 Standard Dynamic Measurement Module
Number of Averages Enter the number of individual data sets to be incorporated into the
average calculation. Averaging reduces the random errors and provides a
more reliable measurement. In Asynchronous mode, the spectrum is averaged. In
Synchronous mode, the time waveforms are averaged.
IMPORTANT: The averaged data is used only for captured time
waveform or FFTs. All data that is calculated from the FFT, such
as bands, is taken from each individual sample, not the
averaged sample.
Tachometer Rotations Enter the number of teeth on the buried shaft gear. Set the value between 1…65,535.
Rotor Rotations Enter the number of teeth on the external shaft gear. These parameters are dimmed in asynchronous sampling.
Gear Ratio Displays the relationship between the Tachometer Rotations and the
Rotor Rotations parameters.
The Tachometer Rotations and Rotor Rotations are used to convert the
speed that is measured by the speed sensor to a shaft speed that is
related by this gear ratio. This information is useful when the shaft of
interest does not have a speed sensor of its own.
When a gear ratio is configured, the synchronous measurements are
synchronized with the rotation of the buried (internal) shaft. This
synchronization includes the Vector, Not 1X, Sum Harmonics, and order-
based Band measurements. Synchronous averaging is also synchronized
with the internal shaft. However, the Speed measurement is not affected
by the gear ratio. The Speed measurement always reflects the speed of
the shaft with the speed sensor (raw tachometer speed divided by
number of pulses per revolution).
This parameter applies only to synchronous sampling.
Table 10 - Spectrum/Waveform Measurement parameters (Continued)
In this field Values are Comments
FMAX options Channel is
configured for
no integration
Channel is
configured for
any integration
10…5000 X X
6250 X
7500 X
8000 X
9375 X
10,000 X
12,500 X
15,000 X
18,750 X
20,000 X