Chapter 1 Before Using
5
1.2.3.2. Communications support devices for RS-485
Description of the equipment needed when connecting to a PC not equipped with an RS485
interface, refer to FRENIC-VG user's manual Section 5.1.4 "Communications support devices for
RS-485".
1.2.3.3. 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.
Show below is an example of adding an inductance component.
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.
RS-485
converter
RS-485 communications cable
Ferrite core
Inverter
Pass the wiring through the ferrite core or
wind the ferrite core with the wiring a few times
Figure 1.2.3-2 Adding an Inductance Component
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