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Rockwell Automation Publication 1444-UM001D-EN-P - June 2018 237
Trend and Transient Capture Chapter 9
Buffers
The dynamic measurement module implements transient data capture by the
application of four configurable buffers where each buffer contains 640
discrete data records and 64 dynamic data records.
The structure (content) of the discrete data record is user-defined and can
contain any measured values, such as speed, 1x magnitude, bias, overall, and
many others from any channel.
The dynamic record content can include a time waveform and/or an FFT that
are processed from any enabled data source. See
Filters on page 124 and Bands
on page 150 .
• Can be allocated to hold either start-up or coast down data.
• A buffer can contain data from only one transient event.
Overflow
When overflow is enabled, if a buffer is filled before a transient is concluded,
then the data acquisition moves to the next available (not latched) buffer of the
same type, and effectively enables definition of:
• One start-up or coast down buffer with 2560 discrete and 256 dynamic
records.
• One start-up and one coast down buffer each with 1280 discrete and
128 dynamic records.
• One start-up or coast down buffer with the standard 640 discrete and 64
dynamic records, and one coast down or start-up buffer with 1920
discrete and 192 dynamic records.
Initiating a Transient Event
A transient event is initiated as the referenced speed crosses below the high or
above the low speed thresholds. The transient data acquisition is begun to the
first available buffer of the applicable type (start up or coast down) that is not
latched.