Mitsubishi Electric FR-A720-0.4K Instruction Manual page 326

Communication operation and setting
(4) RS-485 terminal wiring method
Wiring of one RS-485 computer and one inverter
Wiring of one RS-485 computer and "n" inverters (several inverters)
Computer
RDA
RDB
SDA
SDB
RSA
RSB
CSA
CSB
SG
FG
*1 Make connections in accordance with the manual of the computer used.
Fully check the terminal numbers of the computer since they change with the model.
*2 For the inverter farthest from the computer, set the terminating resistor switch to ON (100
REMARKS
For branching, connect the wires as shown below.
To computer send To computer send
To computer receive To computer receive
To computer ground To computer ground
(5) 2-wire type connection
If the computer is 2-wire type, pass wires across receiving terminals and transmission terminals of the RS-485
terminals to enable 2-wire type connection with the inverter.
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.
316
Computer
RDA
RDB
SDA
SDB
RSA
RSB
CSA
CSB
SG
FG
*1
SG SG
Station 0
- - - - - -
+ + + + + + + +
RXD RXD
+ - + - + - + + - + - + - +
TXD TXD
SG SG SG SG
VCC VCC
Computer
Transmission
enable
Reception
enable
SG
*2
*1
SG
SG SG
Station 1
+ - + + - + - - + - + -
+ +
RXD RXD
To receiving terminal To receiving terminal
of the next inverter of the next inverter
+ - + + - + - + - + + - + -
TXD TXD
To receiving terminal To receiving terminal
of the next inverter of the next inverter
SG SG SG SG
VCC VCC
To next inverter To next inverter
To earth (ground) To earth (ground)
terminal terminal
Inverter
TXD+
TXD-
RXD+
RXD-
Pass a wire
SG
*2
SG
Station n
Ω
side).