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5.3.7: RS485 Connection—Meter to the P40N, P41N or P43N LED Display
Connect the communication wires of the supplied RS485 cable to the Port 1 or Port 4 connection of
the meter. Set the port's Baud Rate to 9600, Address to 1, Protocol to Modbus RTU and Mode to
Slave using the communication software. Insert the other end of the communication wires into the
back of the first LED Display.
The Nexus® 1262/1272 meter's Power Supply DOES NOT SUPPLY POWER TO EXTERNAL
DISPLAYS. You must use a power source, such as the EIG PB1 (12VO). See Figure 5.7 for wiring
details.
RS485 communication is viable for up to 4000 feet (1219 meters). Be sure to do the following:
•
Connect the shield to the shield (S) terminal on the Display port. The (S) terminal on the meter
is used to reference the meter's port to the same potential as the source. It is not an earth-ground
connection. You may also connect the shield to earth-ground at one point.
•
Provide termination resistors at each end for longer runs (typically 500' or more), connected to
the A(+) and B(-) lines. RT is approximately 120 Ohms.
P40N, P41N or P43N LED
Display, Back View
Top
Bottom
Figure 5.9: Meter Connected to P40N, P41N or P43N LED External Display
e
Electro Industries/Gauge Tech
LED Display Port
V+
V-
S
B(-)
A(+)
1262/1272 Port 4
Doc # E151701
R T *
R T *
* *
*
See R T Note on page 5-5..
**
Please refer to Cable Color
Key, page 6-4,
and second bullet, page 5-5.
5-9
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