Fuji Electric FRENIC-HVAC User Manual page 627

Multi-drop connection using the RS-485 communications port 2 (on the terminal block)
Host equipment
USB or RS-232C
TXD RXD
−
USB RS-485 converter
or
−
RS-232C RS-485 converter
Off-the-shelf one
Using the built-in
terminating resistor
Figure 8.2 Multi-drop Connection Diagram (Connecting to the Terminal Block)
Use cables and converters meeting the specifications for proper connection. (Refer to [3]
"Requirements for the cable (COM port 2: for RS-485 connector)" in Section 8.1.4
"Communications support devices."
Host equipment
SD OUT- OUT+
Terminating resistor
(112Ω)
TRD+
TRD-
FG
Switching terminating
8-5
8.1 Overview on RS-485 Communication
RS-485
(4-wire)
IN- IN+
Shield
FRENIC-HVAC series
Station No. 01
DX+
DX-
SD
FRENIC- HVAC series
DX+
Station No. 02
DX-
SD
FRENIC- HVAC series
Station No. n
DX+
DX-
SD
resistors
SW2
112Ω
Inverter 1
(2-wire)
Inverter 2
(2-wire)
Up to 31
inverters
Inverter n
(2-wire)