Reference Manual
00809-0100-4360, Rev BA
August 2008
Rosemount 1151
3-8
Reranging with a Communicator Only
Reranging with only the communicator changes the analog 4 and 20 mA
points independently without a pressure input.
This means that when you change either the 4 or 20 mA setting, you also
change the span. For instance:
If the transmitter is ranged so that
4 mA = 0 inH
2
O, and
20 mA = 100 inH
2
O,
and you change the 4 mA setting to 50 inH
2
O using the communicator only,
the new settings are:
4 mA = 50 inH
2
O, and
20 mA = 100 inH
2
O.
Note that the span was also changed from 100 inH
2
O to 50 inH
2
O, while the
20 mA setpoint remained at 100 inH
2
O.
To obtain reverse output, simply set the 4 mA point at a greater numerical
value than the 20 mA point. Using the above example, setting the 4 mA point
at 100 inH
2
O and the 20 mA point at 0 inH
2
O will result in reverse output.
NOTE
The 4 and 20 mA output is based on the transmitter's existing digital
calibration. Before reranging with the communicator, make sure the
transmitter is correctly interpreting the process variable input. To match the
transmitter's reading in engineering units to plant standard, use the sensor
trim function under “Digital Trim” in this section.
HART Comm. Fast Key Sequence 1, 2, 3, 1, 1
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