Emerson Process Management 3051N User Manual

Reference Manual

00809-0100-4808, Rev CA

June 2008

Rosemount 3051N

2-16

FIGURE 2-7. Transmitter Data 
Flow with Calibration Options.

Deciding Which Trim 
Procedure to Use

To decide which trim procedure to use, you must first determine whether the 
analog-to-digital section or the digital-to-analog section of the transmitter 
electronics is in need of calibration. To do so, refer to Figure 2-7 and perform 
the following procedure:

1.

Connect a pressure source, a HART Communicator, and a digital 
readout device to the transmitter.

2.

Establish communication between the transmitter and
the communicator.

3.

Apply pressure equal to the upper range point pressure (100 inH

2

0, 

for example).

4.

Compare the applied pressure to the Process Variable (PV) line on 
the Communicator On-line Menu. 

IF the PV reading on the 

communicator does not match the applied pressure, and you are 
confident that your test equipment is accurate, 

THEN perform a 

sensor trim.

5.

Compare the Analog Output (AO) line on the communicator on-line 
menu to the digital readout device. 

IF the AO reading on the 

communicator does not match the digital readout device, and you are 
confident that your test equipment is accurate, 

THEN perform an 

output trim.

Sensor Trim

You can trim the sensor using either the full trim or the zero trim function. The 
trim functions vary in complexity, and their use is application-dependent. Both 
trim functions alter the transmitter’s interpretation of the input signal.

A zero trim is a single-point 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. Since this correction 
maintains the slope of the characterization curve, it should not be used in 
place of a full trim over the full sensor range.

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