Rockwell Automation Publication 1444-UM001D-EN-P - June 2018 471
CIP Objects Appendix A
The Record Type Structures are as follows.
See Reading FFT Data
on page 333for details on how to calculate the FFT
from the read data.
See Reading TWF Data on page 332 for details on how to calculate the TWF
from the read data.
Table 209 - FFT (eFFT)
Byte Offset
Within Structure
Structure Member Data Type Description
0 TimestampNanoSec UDINT Subsecond accuracy.
4 TimestampSec UDINT Seconds since 1970.
8 SamplePeriodInSecs REAL Can be used to calculate the bandwidth for the FFT.
12 Identifier DWORD Data source, mode, tacho source, and measurement units.
16 ucDataSelect BYTE If Bit 0 is set, phase array follows the mag array in the returned data array. Otherwise, just the
magnitude array is returned.
Bits 1 and 2 indicate FFT scaling: 0 Peak, 1 Peak to Peak, 2 RMS.
Bits 3 and 4 indicate the data filtering that has been applied.
Bits 5 and 6 indicate the FFT Windowing applied: 0 Normal/Rectangular, 1 Flat-Top, 2 Hanning, 3
Hamming.
17 ucSpeedByte0 BYTE RPM value of the referenced speed source for the FFT data.
Actual RPM = Value/100
Value provided is a 24 bit (3 byte) integer.
First (least significant) byte, bits 0…7.
18 ucSpeedByte1 BYTE Second byte, bits 8…15
19 ucSpeedByte2 BYTE Last byte, bits 16…23
20 ByteCount UDINT The size of the following array in bytes.
24 LineArray REAL The array of FFT line amplitude data.
Table 210 - Waveform (eTWF)
Byte Offset
Within Structure
Structure Member Data Type Description
0 TimestampNanoSec UDINT Subsecond accuracy.
4 TimestampSec UDINT Seconds since 1970.
8 SamplePeriodInSecs REAL Time period between samples or speed and no of samples per revolution.
12 Identifier DWORD Data source, mode, tacho source, and measurement units.
16 RelativeTime UDINT A 24-bit (micro-second) counter-value for finely aligning data.
See Reading Continuous Time Waveforms
on page 329 for information on using this parameter.
20 ByteCount UDINT The size of the following array in bytes.
24 SampleArray REAL The array of waveform data values (samples).
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