15
Reference Manual
00809-0100-4808, Rev DA
Transmitter Functions
October 2016
Transmitter Functions
2.12
Calibration
Calibrating a smart transmitter is different from calibrating an analog transmitter. The one-step
calibration process of an analog transmitter is done in three steps with a smart transmitter.
Rerange—sets the 4 and 20 mA points at the desired pressures;
Sensor Trim—Adjusts the position of the factory characterization curve to optimize the transmitter
performance over a specified pressure range or to adjust for mounting effects;
Analog Output Trim—Adjusts the analog output to match the plant standard or the control loop.
Smart transmitters operate differently than analog transmitters. A smart transmitter uses a
microprocessor and sensor memory that contains information about the sensor’s specific characteristics
in response to pressure and temperature inputs. A smart transmitter compensates for these sensor
variations. The process of generating the sensor performance profile is called factory characterization.
Factory characterization also provides the ability to readjust the 4 and 20 mA points without applying
pressure to the transmitter.
The trim and rerange functions also differ. Reranging sets the transmitter analog output to the selected
upper and lower range points and can be done with or without an applied pressure. Reranging does not
change the factory characterization curve stored in the microprocessor. Sensor trimming requires an
accurate pressure input and adds additional compensation that adjusts the position of the factory char-
acterization curve to optimize transmitter performance over a specific pressure range.
Note
Sensor trimming adjusts the position of the factory characterization curve. It is possible to degrade the
performance of the transmitter if the sensor trim is done improperly or with inaccurate equipment.
Contact Rosemount Nuclear Instruments, Inc. at 952-949-5210 if there are questions.
Table 2-2. Standard Alarm and Saturation Values
Transmitter
Bench calibration tasks
Field calibration tasks
Rosemount
3051ND
Rosemount
3051NG
1. Set output configuration parameters.
a.
Set the process variable units.
b.
Set the output type.
c.
Set the range points.
d.
Set the damping value.
2.
Optional
: Perform a full sensor trim (accurate multimeter required).
3.
Optional
: Perform an analog output trim (accurate multimeter required).
1. Reconfigure parameters if
necessary.
2. Zero trim the transmitter to
compensate for mounting effects or
static pressure effects.
Rosemount
3051NA
1. Set output configuration parameters:
a.
Set the process variable units.
b.
Set the output type.
c.
Set the range points.
d.
Set the damping value.
2.
Optional
: Perform a full sensor trim if equipment available (accurate
absolute pressure source required), otherwise perform the low trim value
section of the full sensor trim procedure.
3.
Optional
: Perform an analog output trim (accurate multimeter required).
1. Reconfigure parameters if
necessary.
2. Perform low trim value section of
the full sensor trim procedure to
correct for mounting position
effects.