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5.3.10: RS485 Connection—Meter to Output Modules
An RS485 cable harness is supplied with the purchase of MBIO (mounting brackets). Wire one end
of the cable into Port 4 of the meter.
Insert the other end of the cable into the communication pins of the Output module's male RS485
side port (see Figure 5.9). See Section 10.3 for details on using multiple Output modules.
The Nexus® 1262/1272 meter's Power Supply WILL NOT SUPPLY POWER TO THE OUTPUT
MODULES. You must use a power source, such as the EIG PSIO or PB1 (12V). RS485 communi-
cation is viable for up to 4000 feet (1219 meters). (See Section 10.2.1 for PSIO details.)
Follow the wiring diagram below and be sure to:
•
Connect the A(+) and B(-) terminals on the meter to the A(+) and B(-) terminals of the female
RS485 port. Connect the shield to the shield (S) terminal. 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 more than 500'), connected to
the A(+) and B(-) lines. RT is approximately 120 Ohms.
NOTE: The meter has some level of termination internally and usually resistors are not needed.
Male Side Port on
Output Module
1262/1272 Port 4
e
Electro Industries/Gauge Tech
R T *
Figure 5.12: Meter Connected to Output Module
Doc # E151701
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.
5-12
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