Zero Trim; Sensor Trim; Recall Factory Trim - Emerson Rosemount 2051 Reference Manual

Calibration
November 2016
5.3.1

Zero trim

A single-point offset adjustment. It is useful for compensating for mounting position effects
and is most effective when performed with the transmitter installed in its final mounting
position.
When performing a zero trim with a manifold, refer to
Note
Do not perform a zero trim on absolute pressure transmitters. Zero trim is zero based, and
absolute pressure transmitters reference absolute zero. To correct mounting position
effects on absolute pressure transmitters, perform a lower trim within the sensor trim
function. The lower trim function provides an offset correction similar to the zero trim
function, but it does not require zero-based input.
5.3.2

Sensor trim

A two-point sensor calibration where two end-point pressures are applied, and all output is
linearized between them. Always adjust the lower trim value first to establish the correct
offset. Adjustment of the upper trim value provides a slope correction to the characteriza-
tion curve based on the lower trim value. The trim values allow you to optimize
performance over your specified measuring range at the calibration temperature. Sensor
trimming requires an accurate pressure input – at least four times more accurate than the
transmitter – in order to optimize performance over a specific pressure range.
Note
The Rosemount 2051 has been carefully calibrated at the factory. Trimming adjusts the
position of the factory characterization curve. It is possible to degrade performance of the
transmitter if any trim is done improperly or with inaccurate equipment.
Note
Rosemount 2051C Range 4 and Range 5 Transmitters require a special calibration
procedure when used in differential pressure applications under high static line pressure.
See "Compensating for line pressure" on page
5.3.3

Recall factory trim

A command that allows the restoration of the as-shipped factory settings of the sensor trim.
This command can be useful for recovering from an inadvertent zero trim of an absolute
pressure unit or inaccurate pressure source.
46
Reference Manual
00809-0300-4101, Rev BB
"Manifold operation" on page
50.
28.
Calibration