Rockwell Automation Publication 1441-UM001B-EN-P - September 2012 81
Setting Up Measurements Chapter 3
Order Normalization for Orders Track Spectrum
There are two requirements for implementing Orders Track measurements. The
Fmax value must fall within the range of 10 to 5000 Hz, and the machine speed
may not vary by more than 10% during the measurement collection.
For example, if you set up a machine that runs at 3500 rpm for an Fmax of 100
Orders, the measurement will not work because the required Fmax is 15,000 Hz.
To Set Up Orders Track FFT Collection
The Dynamix 2500 data collector supports the specification and collection of a
spectrum with an Fmax defined in terms of number of orders for a varying
machine speed. For Orders Track data collection, you are required to use a trigger
to continually determine machine speed.
With orders tracking, the sampling rate is not fixed during the collection period.
Instead, the time spacing between the samples may be constantly varying so that a
fixed number of samples per shaft revolution is collected. The x-axis of the time
waveform is no longer measured in seconds, but instead it is measured in degrees
or shaft position. From this, the corresponding spectral information is no longer
measured in Hz or CPM, but instead it is measured in orders. Orders tracking
removes all non-synchronous frequencies from the spectrum.
Follow these steps to set up route points using the Orders Track collection.
1. Create a collection specification in the Emonitor software that uses Orders
for the maximum frequency (Fmax).
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