Rs485 Communication - Panasonic kw9m User Manual

3.4 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)
(Fig.2)
◆How to connect KW9M and the other devices with 2-wire system
Terminal
station
Correct wiring
○
Incorrect wiring
×
9
KW9M Eco-POWER METER
Terminal
station