Allen-Bradley 1440-SDM02-01RA, User Manual, Page: 71 / 168

Rockwell Automation Publication 1440-UM001D-EN-P - September 2016 71
Configure the XM-124 Standard Dynamic Measurement Module Chapter 2
Table 9 - Signal processing parameters
In this field Values are Comments
Full Scale Choose the maximum signal level that is expected to be processed by the
channel. If the full scale value is peak or peak-to-peak, select the
measurement that is performed (true or calculated) to produce the
overall value. The default value and the available values depend on the
Transducer Nominal Sensitivity selection.
If the Engineering Units of the selected Full Scale value require
integration from the Engineering Units of the selected
Nominal Sensitivity, then an analog Low Pass Filter is applied
before the measurement.
See
Low Pass Filter Corner .
By assuring the absence of high-frequency content, gains can
be applied to maximize the accuracy of the measurements
below the LPF corner frequency.
True The actual or literal measure of the signal. It is the maximum peak in the
time waveform for peak measurements, or the difference between the
maximum and minimum peaks for peak-to-peak measurements.
The True and Calculated radio buttons are dimmed when full
scale is set to an RMS value.
For a pure sine-wave, the true and calculated values are equal.
The true and calculated values diverge as additional signals
are added to the waveform, or as non-sinusoidal or non-
repetitive signals are included.
For protection applications where the objective is to preclude
contact between stationary and moving components, True is
the appropriate measurement because it is a better indication
of actual movement.
For conditioning monitoring applications where the objective
is to indicate the total energy in the system (that is, the overall
value), Calculated is the preferable measurement.
Calculated The RMS value of the time waveform multiplied by the square root of two
(1.414) if measuring the peak value, or two times the square root of two
(2.828) if measuring the peak-to-peak value.
IMPORTANT: When full scale is set to an RMS value, including Calculated
Peak or Calculated Peak-to-Peak, the XM module is configured to accept
input signals as high as 6X the specified full scale without saturating the
electronics. This configuration is set because a signal with moderate RMS
value can have high spikes because RMS is an averaging mechanism. If
True Peak or True Peak-to-Peak is selected, the module is configured to
spread the full scale range over the entire measurement range, without
reserving this 6X headroom used for RMS. This configuration gives better
resolution within the full scale range but causes the signals to be clipped
at levels just above the full scale.
High Pass Filter Corner Choose the high pass filter to apply to the measurement.
• 0.2 Hz
• 1 Hz
• 5 Hz
• 10 Hz
• 40 Hz The high pass filter is useful in removal of low frequency signal
components that can dominate the signal, particularly when
integrating. The high pass filter attenuates frequencies less
than the specified frequency. It passes frequencies greater
than the specified frequency.
Enable Low Pass (Overall) Filter Check to apply a low pass filter to the Overall Measurement. Clear to
disable the low pass filter. The filter is applied only to the Overall measurement. It does
not affect the time waveform, spectrum, or measurements
derived from the spectrum.
Low Pass Filter Corner Enter a value between 100…20,000 Hz. Input signal frequencies greater
than this value are significantly attenuated. This parameter is available only when Enable Low Pass Filter is
checked.
When integrating this (digital), Overall Low Pass Filter Corner
are not always set greater than the analog LPF that is applied
to all integrating measurements.
The filter is automatically applied to all integrated
measurements.
Low Pass Filter
Hardware Series A B
Cut Off Frequency 2 kHz 5 kHz
Roll Off 12 dB/Octave 24 dB/Octave