Honeywell SLG 700 Option Manual page 176

The Process Connector model is only used in cases where the sensor housing is separated from the
process connector by the optional 3m Remote Mount Cable. Since the remote cable may be subject to
a high temperature gradient, a reflection within the process connector is used as the datum point for
locating the transmitter's Reference Plane, eliminating temperature dependences of the level
measurement. This reflection is located at the start of the process connector.
The Surface model is used to describe the characteristics of the reflection caused as the radar pulse
encounters the boundary between a vapor and a liquid product. The Interface model is used to describe
the reflection caused as the radar pulse encounters the boundary between two liquid products. Refer to
Reflection Models on page
present.
The End of Probe model is used to describe the characteristics of the reflection caused as the radar
pulse encounters the physical end of the probe or a centering disk attached to the probe.
The shape of these reflections varies depending on the probe type and end treatment as well as the
transmitter model and other mounting considerations. While the physical end of the probe is always
present, depending on the transmission characteristics and amount of product(s) above the end of the
probe, this reflection may not be noticeable in an echo curve.
Offsets
There are three offsets used by the algorithm in calculating the distance to surface measurement. The
Process Connector Offset (m) is only used for cases where the optional Remote Mount Cable is
installed, as it indicates the observed distance between the Reference and Process Connector
reflections. It is a calculated offset and is therefore a read-only parameter. If the Remote Mount cable
is not installed, this offset will default to zero.
The Reference Plane Offset (m) is a read-only parameter that is determined in the factory for each
transmitter. It corresponds to the distance between the physical reference plane and the internal datum
point, which is the location of either the Reference reflection or the Process Connector reflection,
depending on whether or not the optional remote mount cable has been ordered.
The Calibration Offset (m) is a user-entered offset that may be used to adjust for minor inaccuracies
in the distance measurements caused by differences between the factory and field conditions. It has a
range of ±1.0m and is always treated as a vertical measurement, even if the probe is mounted on an
angle.
Amplitude Tracking:
This feature enhances the sensor to track levels under dynamic conditions or when the radar pulse
attenuations in the media are not well known. Once the sensor has locked onto a correct level, it will
track the amplitude rather than use the initial (user specified) model amplitude. These values are
periodically permanently stored and are hence recovered after a power down. Stored values are cleared
and re-initialized to the user provided amplitudes by turning off Amplitude Tracking (and applying this
change) and then turning it back on it. Amplitude tracking is not a replacement for setting correct
correlation models and will not track pulses whose amplitudes differ more than about 40% from the
user specified pulse model amplitudes.
Under normal circumstances, the only parameter that may require adjustment in the field is the Gain
parameter under the Model tab.
Page 160
159 for a description of when each of these types of reflections may be
FOUNDATION Fieldbus Option User's Guide Rev. 3.0