Owner's manual

Table 5 Modbus Holding Registers (continued)
Address Size Type Value Description Values
4035 2 Float FREQ_MAX
Set maximum frequency for k-w processing. Normally
set by DSP.
User modified if using single or fixed modes
or auto mode with VF_OP_MODE_SETTINGS set to 1
(FIXED_FREQUENCY). Go to Idle mode, then set this
parameter, then select single/fixed.
4037 2 Float FLOW_MIN
Minimum valid flow rate reading in configured display
units
.
4039 2 Float FLOW_MAX
Maximum valid flow rate reading in configured display
units
.
4041 2 Float MIN_QUALITY Minimum quality threshold for VF display and output.
4043 2 Float VF_NYQUIST_HIGH
Define high end of frequency range to use for
determi
ning flow velocity. Defined by:
FREQUENCY_MAX = (Measured Velocity *
VF_NYQUIST_HIGH) / (Sensor Spacing). Example: (10
ft/sec * 0.7) / 0.2 = 35Hz
4045 2 Float VF_NYQUIST_LOW
Define low end of frequency range to use for determining
flow velocity. Defined by: FREQ
UENCY_MIN =
(Measured Velocity * VF_NYQUIST_LOW) / (Sensor
Spacing). Example: (10 ft/sec*0.3) / 0.2 = 15Hz
4047 2 Float
VF_CENTROID_WI
DTH
Define width of peak to use in calculation of flow rate.
4049 2 Float
VF_SEARCH_LIMIT
_LO
W
Define low end of velocity search range to use for
determi
ning 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.
4051 2 Float
VF_SEARCH_LIMIT
_HIG
H
Define high end of velocity search range to use for
determi
ning 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.
4053 2 Float
VF_NYQUIST_INIT_
VAL
This parameter selects the k value (from k-w) where the
algorith
m initially searches for the flow rate.
20959-01 Rev 02 Page 3-22