SCREW TERMINAL
y~~~~ ---", earth
~ , !~~---;. p
ipiN!..: : -:-~~---; N
LC~~~~~-: :,-~:;j 0.4 mm2
BACK VIEW RFT9729
~
CN2
BACK VIEW
NOTES 1. CNI IS USED FOR SENSOR CONNECTION, ONLY ON ROW "d" SEE I.OM
CN2 IS USED FOR OUTPUT CONNECTION, ONLY ON ROW "b" SEE I.OM
2, FOR SUPPLY VOLTAGE CONNECTION 3 POSSIBILITIES
a AC VOLTAGE DIRECTLY TO 3-POLE CONNECTOR OF RFT
b AC VOLTAGE TO CN2 "P" TO 6z OR 2d
"N" TO 2b
" + " TO 2z OR 4z OR 4b OR 4d
RFT MUST BE WIRED AS .
c DC VOLTAGE TO CN2 "+" TO 6z OR 2d
"-" TO 2b
NOTES 1" CN1 IS USED FOR SENSOR CONNECTION" ONLY ON ROW ""d"" SEE IOM
CN2 IS USED FOR OUTPUT CONNECTION, ONLY ON ROW "b" SEE IOM
2" FOR SUPPLY VOLTAGE CONNECTION 3 POSSIBILITIES
a AC VOLTAGE DIRECTLY TO 3-POLE CONNECTOR OF RFT
b AC VOLTAGE TO CN2 ""P"" TO 6z
"N"" TO 2b
" b " TO 2z OR 4z OR 4b
RFT MUST BE WIRED AS -.
c DC VOLTAGE TO CN2 "+" TO 6z
"-" TO 2b
Table 2
RFT9729 to DMS Wiring
RFT9729
Terminal #
Signal
Description
OMS
Terminal #
18b to
2Ob to
22b to
18b to
7 and 10
8
9
None
Signal Ground
Temperature
Period
Ground shield
2.5.5 RS.485 Wiring
To connect the RFT9729 to an RS-485 network, use terminal 10b as the "A" line and
terminal12b as the "8" line. RS-485 wiring should not exceed 4000 feet (1200 meters) of
twisted pair cable. Cable should consist of 24 gauge or larger diameter wire. Twisted pair,
shielded cabl~ should be used if the cable passes through any area which might produce
electromagnetic interference.
A 120 ohm, 112 watt resistor should be installed at each end of the network cable. These
termination resistors ensure proper communications by reducing electrical reflections in
the cable. See Figure 2-4, RS-485 Wiring.
As many as 15 RFT9729 units can be connected to a single network. Using the RFT9729
in a networking (multidrop) mode requires each transmitter to be assigned a unique ad-
dress in order to prevent contention on the line. In the RS-485 networking mode, it may
be desirable to engage the "485 mA Live" jumper selection (see Section 3.1, Jumper
Configuration on the Processor Board) in order to preserve active milliamp outputs on
each transmitter. For further information on the communications protocol requirements
needed to implement an RS-485 network, refer to the Remote Flow Transmitter Digital
Communications Instruction Manual, July, 1 1989, PIN 1002789, or contact Micro Mo-
tion, Inc. at 1-8001322-JUMP, in the U.S. or at 31-08385-63312 in Europe.
2.5.6 Multidrop Wiring for
the Milliamp Output
To connect the RFT9729 in a HART compatible network, the milliamp outputs from each
transmitter in the network need to be connected together feeding into a common load re-
sistor of approximately 250 ohms. Before connecting each transmitter into the network,
the transmitter must be assigned a unique multidrop address using the numbers 1
through 15. Doing this will default the milliamp output to a constant 4 mA level. The "485
mA Live" jumper (see Section 3.1) should not be engaged in this mode of operation to
limit the overall current into the common load resistor.
A maximum of 10 transmitters may be connected in a HART multidrop network. Other
Rosemount SMART FAMILY transmitters may participate in a HART compatible network.
See Figure 2-5, HART Network Wiring. A single 268 or HART compatible control system
can communicate with any of the transmitters in the network over the same two wire pair.
16