Step 3: Connect The Wiring And Power Up - Emerson Rosemount 3095FB MultiVariable MODBUS Quick Installation Manual

Quick Installation Guide
00825-0100-4738, Rev BA
October 2009
S 3: C
TEP ONNECT THE
Use the following steps to wire the transmitter:
1. Remove the housing cover on the side marked FIELD TERMINALS.
2. Connect the lead from the positive power supply terminal to the "+" terminal
(PWR/COMM) and the lead from the negative power supply terminal to the "–" terminal.
3. Connect the transmitter to the RS-485 bus:
Connect the A lead to the "A" terminal.
Connect the B lead to the "B" terminal.
NOTE
Improper field wiring connections may damage the 3095FB. Do not connect power wiring to
the RS-485 terminals. Twisted pairs should be used for best results. Twisted pair is required
for RS-485 bus wiring. Runs under 1000 ft (305 m) should be AWG 22 or larger. Runs from
1000 to 4000 feet (305 to 1219 m) should be AWG 20 or larger. Wiring should not exceed
AWG 16.
4. Plug and seal unused conduit connections.
5. Install wiring with a drip loop. Arrange the drip loop so the bottom is lower than the
conduit connections and the transmitter housing.
Figure 8 shows wiring connections necessary to power a 3095 and enable communications.
The 3095FB requires a power supply between 7.5 - 30 Vdc. RS-485 signal wiring requires
2-wire half duplex RS-485 Modbus with 8 data bits, one stop bit, and no parity.
Figure 8. Transmitter Wiring Diagram
Twisted pair required
120 
User-Provided
Power Supply
NOTE
Installation of the transient protection terminal block does not provide transient protection
unless the 3095 case is properly grounded. The converter cables may be connected directly
to the RS-485 bus or the transmitter terminals. Be sure to observe proper polarity.
W
IRING AND
RS-485 Bus
3095FB
A
B RS-485
+
- PWR
+
-
Rosemount 3095FB
P U
OWER P
Converter
A
120 
B
9