Emerson Rosemount 3144P, Reference Manual

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96
Reference Manual
00809-0100-4021, Rev JA
HART Commissioning
April 2017
HART Commissioning
Transmitter behavior with Intermittent Sensor Detect OFF
When the Intermittent Sensor Detect feature is switched OFF, the transmitter tracks all process
temperature changes, even from an intermittent sensor. (The transmitter in effect behaves as though
the threshold value had been set at 100 percent.) The output delay due to the intermittent sensor
algorithm will be eliminated.
3.11.5 Open sensor holdoff
The Open Sensor Holdoff option, at the normal setting, enables the transmitter to be more robust under
heavy EMI conditions. This is accomplished by the software having the transmitter perform additional
verification of the open sensor status prior to activating the transmitter alarm. If the additional
verification shows that the open sensor condition is not valid, the transmitter will not go into alarm.
For users of the transmitter that desire a more vigorous open sensor detection, the Open Sensor Holdoff
option can be changed to a fast setting where the transmitter will report an open sensor condition
without additional verification of the open condition.
3.12 Diagnostics and service
Diagnostics and service functions listed below are primarily for use after field installation. The
Transmitter Test feature is designed to verify that the transmitter is operating properly, and can be
performed either on the bench or in the field. The Loop Test feature is designed to verify proper loop
wiring and transmitter output, and should only be performed after you install the transmitter.
3.12.1 Loop test
Field Communicator
The Loop Test command verifies the output of the transmitter, the integrity of the loop, and the
operations of any recorders or similar devices installed in the loop.
3.13 Multidrop communication
Multidropping refers to the connection of several transmitters to a single communications transmission
line. Communication between the host and the transmitters takes place digitally with the analog output
of the transmitters deactivated. Many Rosemount transmitters can be multidropped. With the HART
communications protocol, up to 15 transmitters can be connected on a single twisted pair of wires, or
over leased phone lines.
Multidrop installation requires consideration of the update rate necessary from each transmitter, the
combination of transmitter models, and the length of the transmission line. Communication with
transmitters can be accomplished with Bell 202 modems and a host implementing HART Protocol. Each
transmitter is identified by a unique address (1–15) and responds to the commands defined in the HART
Protocol. Field communicators and AMS Device Manager can test, configure, and format a multidropped
transmitter the same way as a transmitter in a standard point-to-point installation.
HART 5 Fast Keys
2, 2, 7, 4
HART 7 Fast Keys
2, 2, 7, 4
HART 5 Fast Keys
3, 5, 1
HART 7 Fast Keys
3, 5, 1