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70
Reference Manual
00809-0100-4140, Rev AA
January 2017
5.3
Analog output calibration
The analog output can be calibrated to match the user's measurement system. The Analog
Output Trim (4-20mA Output Trim) will calibrate the loop at the 4 mA and 20 mA points.
5.3.1
Trimming the analog output
The
Analog Output Trim
commands allow you to adjust the level detector’s current output at
the 4 and 20 mA points to match the plant standards. This trim is performed after the
digital to analog conversion so only the 4-20mA analog signal will be affected.
graphically shows the two ways the characterization curve is affected when an analog
output trim is performed.
Figure 5-1. Analog Output Trim Example
A. Before trim
B. After Trim
Note
If a resistor is added to the loop, ensure that the power supply is sufficient to power the level
detector to a 20 mA output with additional loop resistance. Refer to
.
5.3.2
Site calibration of analog output
This command starts the on-site calibration of the analog output. It should only be
performed by authorized persons.
Note
A reference meter (ammeter) is a required for measuring the actual output current at 4 mA
and 20 mA. See
for the analog output connections.
Fast Keys
3, 4, 4, 2
A
A
B
B
mA output
mA output
Summary of Contents for Rosemount 2140
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