
184
Reference Manual
00809-0100-4811, Rev DA
Appendix C: Rosemount 3300 Series with HART
®
to Modbus
®
Converter
January 2015
Rosemount 3300 Series with HART
®
to Modbus
®
Converter
Star topology
For a Star Topology Connection of the Rosemount 3300 Series, the transmitter with the longest
cable run needs to be fitted with a 120- termination resistor.
Figure C-6. Star Topology Connection of 3300 Transmitters
C.6 Establish HART communication
The Rosemount 3300 Series Transmitter can be configured using the Rosemount Radar
Configuration Tools (RCT) PC software, or a Field Communicator. Configuration is done by
sending HART commands through the HART to Modbus Converter (HMC) to the 3300
transmitter electronics. To establish HART communication, connect to the MA (+)/MB (-)
terminals, or to the HART terminals. Both alternatives are described below.
C.6.1 Connect to the MA (+)/MB (-) terminals
The 3300 level transmitter can be configured with RCT using the MA (+), MB (-) terminals.
An RS-485 Converter is required to connect to the transmitter.
The transmitter will try to establish communication using different protocols during 20 second
timeslots from time of startup.
Figure C-7. RS-485 Communication after startup
For Star Topology
connection, connect
the 120
termination resistor
to the transmitter
with the longest
cable run.
HART
20 seconds
Modbus RTU
20 seconds
Configured
protocol
(Modbus RTU,
Levelmaster, or
Modbus ASCII)
20 seconds
HART
20 seconds
Time
0 s 20 s 40 s 60 s 80 s 100 s
Configured
protocol
(Modbus RTU,
Levelmaster, or
Modbus ASCII)
20 seconds
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