Terminal Specifications For Rs-485 Communication - Fuji Electric FRENIC-HVAC User Manual

8.1.2

Terminal specifications for RS-485 communication

[ 1 ] RS-485 communications port 1 (for connecting the keypad)
The port designed for a standard keypad uses an RJ-45 connector having the following pin
assignment:
Pin Signal name
1 and 8 Vcc
2 and 7 GND
3 N/A
6 NC
4 DX-
5 DX+
* For details about SW3, refer to Chapter 2, Section 2.3.2 "Setting up the slide switches."
Pins 1, 2, 7, and 8 on the RJ-45 connector are exclusively assigned to power supply and
grounding for keypads. When connecting other devices to the RJ-45 connector, take care not
to use those pins. Failure to do so may cause a short-circuit hazard. Use pins 4 and 5 only.
[ 2 ] RS-485 communications port 2 (control circuit terminals)
The FRENIC-HVAC has terminals for RS-485 communications on the control circuit terminal block.
The details of each terminal are shown below.
Signal name
SD
DX－
DX＋
* For details about SW2, refer to Chapter 2, Section 2.3.2 "Setting up the slide switches."
Function
Power source for the keypad
Reference potential
Not available.
Not used.
RS-485 data (-)
RS-485 data (+)
Function
Shield terminal
RS-485 data (-)
RS-485 data (+)
8-3
8.1 Overview on RS-485 Communication
Remarks
5 V power lines
Grounding pins
No connection
No connection
Built-in terminating resistor: 112Ω
Open/close by SW3*
Remarks
Built-in terminating resistor: 112Ω
Open/close by SW2*