Mitsubishi Electric FR-A700 Technical Manual page 91

(4) RS-485 terminal system configuration
common
Use the RS-485 terminals to perform communication
operation from a personal computer etc. When the
PU connector is connected with a personal, FA or
other computer by a communication cable, a user
program can run and monitor the inverter or read and
write to parameters.
1) Connection of a computer to the inverter (1:1
connection)
Computer
Inverter
RS-485
terminals
RS-485
interface/
*
terminals
Twisted pair cable
* Set the terminating resistor switch to the 100Ω position.
2) Combination of computer and multiple inverters
(1:n connection)
Station 0
Computer
Inverter
RS-485
RS-485
terminals
interface terminals
*
Twisted pair cable
Station 0
Computer
RS-232C
Inverter
converter
RS-485
Maximum
terminals
RS-232C
15m
*
cable
Converter
Twisted pair cable
* Set only the terminating resistor switch of the
remotest inverter to the 100Ω position.
(5) RS-485 terminal wiring method
1) Wiring of one RS-485 computer and one inverter
Computer
RDA
RDB
SDA
SDB
RSA
RSB
CSA
CSB
SG
FG
2) Wiring of one RS-485 computer and n (multiple)
inverters
Computer
RDA
RDB
SDA
SDB
RSA
RSB
*1
CSA
CSB
SG SG
Station 0
FG
*1 Make connection in accordance with the instruction
manual of the computer. Check the terminal numbers of
Computer
Inverter
terminals
Maximum
RS-232C
15m
cable
Converter
Twisted pair cable
*Set the terminating resistor switch to the "100Ω" position.
Station 1 Station n
Inverter Inverter
RS-485 RS-485
terminals terminals
* *
Station 1 Station n
Inverter Inverter
RS-485 RS-485
terminals terminals
* *
common
*2
*1
SG
SG SG SG SG
Station 1 Station n
the computer since terminal number differs with the
model.
*2 For the inverter farthest from the computer, set the
terminating resistor switch to ON (100Ω position).
*3 For branching, connect the wires as shown below.
To computer send
To computer receive
To computer ground
(6) Two-wire type connection
RS-485
*
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 RS-485 terminal.
A program should be created so that transmission is
disabled (receiving state) when the computer is not
sending and receiving is disabled (sending state)
during sending to prevent the computer from
receiving its own data.
Transmission
enable
Receiving
enable
*2
84
SPECIFICATIONS
- - - + - + - + -
+ + + + +
RXD
+ - + - + - + + - + - + - +
TXD TXD
SG SG SG SG
VCC
common
Computer
Pass a wire
SG
RXD
To receiving terminal
of the next inverter
To receiving terminal
of the next inverter
VCC
To next inverter
To earth (ground)
terminal
Inverter
TXD+
TXD-
RXD+
RXD-
SG