Mitsubishi Electric FR-E720-0.1K(SC) Instruction Manual page 213

(3) Connection with RS-485 computer
Wiring of one RS-485 computer and one inverter
Computer side terminals *1
Receive data
Receive data
Send data
Send data
Signal ground
Wiring of one RS-485 computer and "n" (multiple) inverters
Computer *1
Receive
Send
SG
∗1 Make connection in accordance with the instruction manual of the computer to be used with.
Fully check the terminal numbers of the computer since they vary with the model.
∗2 The inverters may be affected by reflection depending on the transmission speed or transmission distance. If this reflection hinders
communication, provide a terminating resistor. If the PU connector is used to make a connection, use a distributor since a terminating
resistor cannot be fitted. Connect the terminating resistor to only the inverter remotest from the computer. (Terminating resistor: 100Ω)
NOTE
Do not use pins No. 2, 8 of the communication cable. (Refer to page 211)
When making RS-485 communication among the FR-E700 series, FR-E500 series and FR-S500 series, incorrect
connection of pins No.2 and 8 (parameter unit power supply) of the above PU connector may result in the inverter
malfunction or failure. (Refer to page 211)
(4) Two-wire type connection
If the computer is 2-wire type, a connection from the inverter can be changed to 2-wire type by passing wires across
reception terminals and transmission terminals of the PU connector pin.
Transmission enable
REMARKS
A program should be created so that transmission is disabled (receiving state) when the computer is not sending and reception
is disabled (sending state) during sending to prevent the computer from receiving its own data.
The passed wiring length should be as short as possible.
Cable connection and signal direction
Cable connection and signal direction
Communication cable
SG
Station 1
Inverter
Computer
Reception enable
Communication operation and setting
Communication cable
2
0.2mm or more
SG
Station 2
Inverter
Inverter
SDA
SDB
RDA
RDB
Pass a wire
SG
SG
Inverter
PU connector
SDA
SDB
RDA
RDB
SG
Terminating
*2
resistor
SG
Station n
Inverter
4
213