Fisher-Rosemount 3095FT, Manual

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Rosemount Model 3095FT HART Flow Transmitter
6-4
ELECTRONICS MODULE The major functions of the electronics module are to send process
variables to the flow equation, log the appropriate audit trail data in
memory, and provide a HART output for communications. These tasks
are accomplished by a single electronics board incorporating ASIC and
surface-mount technology. The main components of the board are the
flow/output microprocessor and nonvolatile memory for logging flow,
configuration, and event data.
The electronics module accepts the three corrected digital process
variables from the sensor module. The output section of the electronics
module converts the digital signal to HART protocol, and handles
communication with the Model 3095FT User Interface Software. Also
available is an LCD meter that plugs into the electronics board and
displays process variables, flow calculations, and transmitter diagnostic
messages
Flow/Output
Microprocessor The flow/output microprocessor controls operation of the transmitter. In
addition, it performs flow calculations, sensor linearization,
engineering unit conversion, transmitter self-diagnostics, reranging,
damping, and digital communication.
Nonvolatile Memory The nonvoltaile memory (EEPROM) holds all transmitter configuration
data. This memory also holds range values if the Model 3095FT was
reranged at the factory, and it also stores all variable, daily and event
logs. The data in this memory remains intact even when no power is
applied.
RAM
(Random Access Memory) The RAM is a temporary workspace used by the microprocessor for its
calculations. It cannot be accessed directly by the user.
HART Digital
Communication The Model 3095FT communicates via the industry standard HART
protocol, which uses the Bell 202 Frequency Shift Keying (FSK)
technique. Remote communication is accomplished by superimposing a
high-frequency signal on top of the fixed output signal. Since all
communication is accomplished using HART, the Model 3095FT does
not provide a 4–20 mA output signal.
Personal Computer A personal computer operating the Model 3095FT User Interface
Software communicates to the Model 3095FT over the HART interface.
The User Interface Software is used to both configure and calibrate the
Model 3095FT, and is also used to retrieve Model 3095FT logged data.