Reference Manual
00809-0100-4360, Rev BA
August 2008
4-11
Rosemount 1151
It may be necessary to calibrate the current output circuitry after a period of
time and use. The 4–20 mA output trim function can also be used to make
adjustments to allow for peculiarities of a particular readout device in the loop.
4–20 mA Analog Output Trim
A 4–20 mA output trim adjusts the transmitter milliampere output to match a
plant’s current standard. Use this procedure when trimming the converter
using a current meter.
4–20 mA Analog Output Trim Using Other Scale
To trim the output using a voltage or other meter, connect the meter across a
resistor in the loop. For best accuracy, use a precision resistor. The scaling
function may be used if the meter displays other units, such as 0–100%.
NOTE
If a resistor is added to the loop, before proceeding, ensure that the power
supply is sufficient to power the transmitter to a 20 mA output with the
additional loop resistance.
ANALOG CALIBRATION
Calibration Overview Calibration of the Rosemount 1151 Analog Pressure Transmitter is simplified
by its compact and explosion-proof design, external span and zero
adjustments, separate compartments for electronics and wiring, and
weatherproof construction. Descriptions of span, linearity, zero adjustments,
and damping follow.
Figure 4-6. Output Trim
Quick Calibration
Procedure
(for E and G Electronics)
The following Quick Calibration Procedures are for those users who are
already familiar with the Rosemount 1151 Analog.
NOTE
The zero and span adjustments are interactive. For applications requiring
large elevated or suppressed values, refer to Elevated or Suppressed Zeros
on page 3-7.
HART Comm. Fast Key Sequence 1, 2, 3, 2, 1
HART Comm. Fast Key Sequence 1, 2, 3, 2, 2
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