404 Rockwell Automation Publication 1444-UM001D-EN-P - June 2018
Appendix A CIP Objects
The Record Type Structures are as follows.
See Reading FFT Data
on page 333 for details on how to calculate the FFT
from the read data.
Table 131 - Discrete Data
Byte Offset
Within
Structure
Structure Member Data Type Description
0 TimestampNanoSec UDINT Subsecond accuracy.
4 TimestampSec UDINT Seconds since 1970.
8 Reserved DWORD
12 Reserved DWORD
16 Params0 DWORD Set bits indicate which parameters are included in the
data array. The values in DataArray are in the order of
the set bits. Values are the same as configuration tag
TransientCapture.DiscreteParams1…4.
20 Params1 DWORD
24 Params2 DWORD
28 Params3 DWORD
32 ByteCount UDINT The size of the following array in bytes.
36 DataArray REAL The array of data.
Table 132 - FFT (eFFT_TDx)
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 ucDataSelect BYTE Not used for transient data. Only Magnitude data is available.
Bit 3 is set if FFT Data Filter has been applied.
17 ucSpeedByte0 BYTE RPM value of the referenced speed source for the FFT data.
Actual RPM = Value/100
Value that is 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.
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