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152 Rockwell Automation Publication 1440-UM001D-EN-P - September 2016
Appendix B CIP Objects
Where Float Data
n
is the value for the nth waveform point, and 0 £ n £
Number of Waveform Points.
The Get_Spectrum_Chunk and Get_Waveform_Chunk services use the same
request and response parameters.
Table 80 - Get_Spectrum_Chunk/Get_Waveform_Chunk Request Parameters
Name Data Type Description of Request Parameters Semantics of Values
Initial DWORD Offset UINT The offset of the first 32-bit value within the data
structure to be returned.
0 <= offset < size of the data structure in DWORDs.
For example:
Offset = 0 refers to bytes 0…3 (the number of lines or points value)
Offset = 1 refers to bytes 4…7 (the FMAX or period values)
Offset = 2 refers to bytes 8…11 (the amplitude reference value)
Offset = 3 refers to bytes 12…15 (the first pair of normalized
values)
Offset = 4 refers to bytes 16…19 (the second pair of normalized
values)
Number of DWORDs USINT The number of 32-bit values from the data
structure to be returned.
This value must be small enough to fit in the explicit message buffer.
The buffer is likely less than the total size of the data structure so
that several calls to the service are required to get the entire data
structure.
Table 81 - Get_Spectrum_Chunk/Get_Waveform_Chunk Response Parameters
Name Data Type Description of Response Parameters Semantics of Values
Number of DWORDs USINT The number of 32-bit values that are returned in
the Data Chunk array of the response. (Can be less
than the number of DWORDs requested.)
If fewer DWORDs are returned than requested, the end of the data
structure has been reached (the request went beyond the end of the
array).
Data Chunk Array of DWORD The requested portion of the data structure.