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3.6 RS485 Communication
・
When using shielded cable for the RS485 transmission line, ground one end.
Use a class D dedicated earth for grounding. Do not share a ground with other earth lines. (Fig. 1)
・
For terminal stations of both side including the upper device, termination resistors should be
connected. KW9M Eco-POWER METER doesn’t have any built-in termination resistors.
Connect 120Ω, 1/2W or more termination resistor between [A+] and [B-] of Eco-POWER METER that
is connected the end of RS485 transmission line. The RS485 transmission line shielded cable should
be grounded at the end KW9M Eco-POWER METER. (Fig. 1)
・
Be sure to connect with daisy chain the RS485 transmission line between each unit.
Do not use a splitter. (Fig. 2)
・
To avoid noise, separate the transmission line from high-voltage line (power supply, voltage line).
(Fig.1)
◆
How to connect KW9M and the other devices with 2-wire system
(Fig.2)
Correct wiring
○
Incorrect wiring
×
Terminal
Terminal
station
station
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