CiDRA Use of Foundation Fieldbus Protocol with SONARtrac Transmitters - Manual (Page 20)

Table 3 Transducer Block Configurations (Page 7)
FLOW_NYQUIST_HIGH Float R/W
Define high end of frequency range to use for
determining flow velocity. Defined by:
FREQUENCY_MAX = (Measured Velocity *
VF_NYQUIST_HIGH) / Sensor Spacing. Example: (10
ft/sec*0.7) / 0.2 = 35Hz
FLOW_NYQUIST_LOW Float R/W
Define low end of frequency range to use for
determining flow velocity. Defined by:
FREQUENCY_MIN = (Measured Velocity *
VF_NYQUIST_LOW) / Sensor Spacing. Example: (10
ft/sec*0.3) / 0.2 = 15Hz
FLOW_CENTROID_WIDTH Float R/W Define width of peak to use in calculation of flow rate.
FLOW_VEL_SEARCH_LIMIT_LOW Float R/W
Define low end of velocity search range to use for
determining flow velocity. Defined by: Velocity_Min =
(FREQ_MAX * Sensor Spacing) /
VF_SEARCH_LIMIT_LOW. Example: at 10ft/sec* (10
ft/sec*0.7) / 0.2 = 35Hz then (35Hz * 0.2) / 0.9 = 7.78
ft/sec. This defines the start ft/sec search point for the
actual flow velocity peak. Must be set greater than
value set for VF_NYQUIST_HIGH.
FLOW_VEL_SEARCH_LIMIT_HIGH Float R/W
Define high end of velocity search range to use for
determining flow velocity. Defined by: Velocity_Max =
(FREQ_MIN * Sensor Spacing) /
VF_SEARCH_LIMIT_HIGH. Example: at 10ft/sec* (10
ft/sec*0.3) / 0.2 = 15Hz then (15Hz * 0.2) / 0.15 = 20
ft/sec. This defines the start ft/sec search point for the
actual flow velocity peak. Must be set less than value
for VF_NYQUIST_LOW.
FLOW_NYQUIST_INITIAL_VALUE Float R/W
This parameter selects the k value (from k-w) where the
algorithm initially searches for the flow rate.
FLOW_DECIMATION
Unsigned
Long
R/W
Flow Decimation
FLOW_WINDOW_TYPE
Unsigned
Long
R/W
Algorithms always use Hanning window. Windows raw
data samples of NFFT size* then zero pads* then
computes FFT.
FLOW_DETREND
Unsigned
Long
R/W
Enable/disable detrend of time series data of NFFT size
before windowing and zero padding. 0 - Do not detrend
time series data* 1 - Detrend time series data.
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