E-Mon E-D5-600800-S*SPL3-V3KIT3 - Manual (Page 29)

DIN-MON™ SMART METER
29 62-0442—04
4.8 Wiring the Communications
4.8.1 RS-485 Network and Wiring
RS-485 communication allows a computer, automation system, or
modem to communicate with one or more Din-Mon™ meters. You can
connect as many as 52 meters along a 4,000-foot RS-485 cable run
with Belden 3106A cable or equivalent. The cable rating of 600V allows
the RS-485 network to be used in cabinets with service voltage up to
600V. Meter is supplied with internal bias of Belden 3106A 45K Ohms, some
installations may require additional biasing. A typical RS-485 network requires the use
of one 120 Ohm termination resistor at each end of the RS-485 cable run. The
termination resistors are installed across the ‘+’ (high) and ‘–’ (low) terminals.
Din-Mon™ meter supports 3 protocols on RS-485 connection operating in half-duplex,
stop-and-wait mode. They are available in Modbus RTU, BACnet MS/TP, or EZ7.
The Din-Mon™ meter RS-485 network uses the convention ‘+’ and ‘–’ to represent the
lines ‘A’ and ‘B’, defined by the RS-485 standard, respectively; in addition, “SC” is used
for signal common.
The daisy-chain topology is used to link multiple meters together for one connection
back to the computer, automation system, or modem.
Fig. 23. A 3-Wire RS-485 Network Diagram.
NOTE: Belden 3601A recommended for RS-485 up to 600V environment appli-
cations. Torque screws to 2 in-lbs.
M35109
BELDEN 3106A
M35156
SC LINE
– LINE
+ LINE
SC – + SC – + SC – +
120 OHM TERMINATION RESISTORS SHOULD BE INSTALLED ACROSS + (PLUS) AND – (MINUS)
AT THE BEGINNING AND END OF THE RS-485 NETWORK.
1
TERMINATION
RESISTOR
SH (SHIELD)
TERMINATION
RESISTOR
1 1