Emerson Rosemount 3100 Series - P025 (Temperature; P026 (Threshold; P030 to P039 (Profile Points; P040 (Transmit Power Control

Reference Manual
00809-0100-4840, Rev. BA
July 2008
F-17
Rosemount 3100 Series
P025 (Temperature) P025 Description
This is for temperature correcting of the speed of sound entered in P024. The
corrected speed of sound is displayed in D914.
For automatic (dynamic) corrections using the integrated temperature sensor,
select the AUTO option. The live temperature measurement is displayed at
D915.
The temperature sensor measures the air temperature at the transmitter
rather than measuring the average temperature across the ullage space.
If the average temperature is known, this can be entered in P025. The same
value is indicated by D915 and is used to calculate the speed of sound.
(Negative values are allowed.)
If the temperature sensor fails and AUTO is selected, the P025 setting reverts
to 68 °F (20 °C).
P026 (Threshold) P026 Description
This sets the sensitivity of the echo detection circuits in the transmitter. P026
defines the minimum signal level as a percentage, above which an echo is
detected and treated as a potentially valid surface or target.
When P026 is set to AUTO, the sensitivity is automatically adjusted over a
range of values, depending on the echo strengths being received. The
threshold is adjusted to one quarter of the peak value of the largest signal
detected to give best overall performance.
P026 can be a constant value, which may be needed to overcome particular
site difficulties or special conditions. For example, setting the threshold to
20 (%) may be used to avoid echoes from rough brickwork on a sump wall.
The value of P026 may be adjusted in conjunction with parameters P023,
P043, P048, and P063.
Minimum value:
0.0 (if not using Auto)
Maximum value:
99.9 (if not using Auto)
P030 to P039
(Profile Points)
P030 to P039 Description
For the purpose of these parameters, see “P011 = “Special”” on page F-6.
P040
(Transmit Power Control)
P040 Description
The transmitted ultrasonic energy can be controlled automatically to avoid
strong close echoes saturating the electronics of the transmitter.
When this mode is enabled, P044 has no affect.