Noise Suppression - Fuji Electric FRENIC-HVAC User Manual

[ 2 ] Cable for RJ-45 connector (COM port 1)
Use a standard 10BASE-T/100BASE-TX LAN cable (US ANSI/TIA/EIA-568A category 5 compliant,
straight type).
The RJ-45 connector (COM port 1) has power source pins (pins 1, 2, 7 and 8) exclusively
assigned to keypads. When connecting other devices to the RJ-45 connector, take care not to
use those pins. Using them will cause a short-circuit hazard. Use pins 4 and 5 only.
[ 3 ] Cable for RS-485 connector (COM port 2)
To ensure the reliability of connection, use twisted pair shield cables for long distance transmission
AWG 16 to 26.
Recommended LAN cable
Manufacturer: FURUKAWA Electric Co., Ltd.
AWM2789 Cable for long distance connection
Type (Product code): DC23225-2PB
[ 4 ] Branch adapter for multi-drop
An RS-485 communications network for inverters utilizes 2-wire 10BASE-T LAN cables fitted with
an RJ-45 connector at both ends. To connect those inverters to the network in multi-drop mode, use
branch adapters for multi-drop.
Recommended branch adapter
SK Koki (Japan): MS8-BA-JJJ
8.1.5

Noise suppression

Depending on the operating environment, instruments may malfunction due to the noise generated by
the inverter. Possible measures to prevent such malfunction are: separating the wiring, use of shielded
cable, isolating the power supply, and adding an inductance component. Shown below is an example
of adding an inductance component.
 Refer to the RS-485 Communication User's Manual, Chapter 2, Section 2.2.4 "Noise
suppression" for details.
Adding inductance components
To suppress or eliminate noise for keeping the network in high noise immunity level, insert inductance
components such as choke coils in series in the signal circuit, or pass the RS-485 communications
cable through a ferrite core ring or wind it around by 2 or 3 turns as shown below to keep the
impedance of the signal lines high.
Figure 8.4 Adding an Inductance Component
8-7
8.1 Overview on RS-485 Communication