Mitsubishi QJ71C24N User Manual page 16

POINT
If the module is the first or last station on the RS-422/485 line, connect the following
terminal resistor to the RS-422/485 interface with reference to the examples shown below.
Data communication will be disturbed if a terminal resistor is not used.
• For RS-422 communication .............................. 330 Ω 1/4 W
• For RS-485 communication .............................. 110 Ω 1/2 W
The R in the examples shown below indicates a terminal resistor.
(1) Example of one-to-one connection between an external device and the
module (RS-422, RS-485)
Terminal
resistor
(2) Example of one-to-n connection between an external device and the
module (RS-485 between C24s)
(a) Connecting an external device and the module using RS-232
External device
RS-232
SD
RD
(b) Connecting an external device and the module using RS-485
External device
SDA
R
SDB
RDA
R
RDB
SG
FG
RS-422/485
Module
Signal name
SDA
SDB
RDA
R
RDB
SG
FG
FG
C24 1)
SDA
R
SDB
RDA
R
RDB
SD SG
RD FG
Link operation
C24 1)
SDA
SDB
RDA
RDB
SG
FG
RS-422/485
cable
C24 2)
SDA
SDB
RDA
RDB
SG
FG
RS-422/485
cable
C24 2)
SDA
SDB
RDA
RDB
SG
FG
RS-422/485
cable
10
External device
Terminal
Signal name
resistor
RDA
R
RDB
SDA
SDB
RSA
RSB
CSA
CSB
SG
FG
C24n
SDA
R
SDB
RDA
R
RDB
SG
FG
RS-422/485
cable
Terminal resistor
R
C24n
SDA
R
SDB
RDA
R
RDB
SG
FG
cable
Terminal resistor
R