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4-Channel Power Meters
Installation and Operation
#N2-KW320 and N2-KW320Q Series– 8/14/23
Figure 11: 1LL, 2CT
Communication
The KW320 meter supports user selectable RS-485 serial Modbus-RTU, BACnet™ MS/TP, dual Ethernet ports with multiple
communication protocols, and Wi-Fi communication allows seamless integration with data acquisition systems.
KW320 series meter uses RS485 serial communication for both BACnet MS/TP and Modbus RTU protocols. The terminals of
communication are A, B and S (14, 15, 16). A is differential signal +, B is differential signal - and S is connected to the shield of the
twisted pair cables. Up to 32 devices can be connected on a RS485 bus. Use good quality shielded twisted pair cable, AWG22
(0.5mm2) or higher. The overall length of the RS485 cable connecting all devices should not exceed 1200m (40000 ft). The
KW320 series meter is used as a slave device of masters such as a PC, PLC, Data Collector or RTU.
If the master does not have RS485 communication port, a converter (such as a RS232/RS485 or a USB/RS485 converter) will be
required. Typical RS485 network topologies include line, circle and star (Wye). The shield of each segment of the RS485 cable
must be connected to the ground at one end only.
Every A(+) should be connected to A(+), B(-) to B9(-) or it will influence the network or even damage the communication interface.
The connection topology should avoid "T" type which means there is a new branch and it does not begin from the beginning point.
Keep communication cables away from sources of electrical noise whenever possible.
When using a long communication cable to connect several devices, an anti-signal reflecting resistor (typical value 120Ω-
300Ω/0.25W) is normally added to the end of the cable beside the last meter if the communication quality is distorted.
Use RS232/RS485 or USB/RS485 converter with optical isolated output and surge protection.
Refer to Chapter 6 of this manual for additional details on both Modbus RTU and BACnet MS/TP communication.
The KW320 meter also includes dual Ethernet ports that enables seamless integration utilizing BACnet IP, Modbus TCP, IPv6,
and additional communication protocols. Refer to Chapter 5 of this manual regarding wiring and meter configuration as it relates
Ethernet.
Specifications subject to change without notice.
Catalog No. 11-808-974-01
Page 19 of 20
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