User`s manual

10
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
R
R
Module
Signal name
SDA
SDB
RDA
RDB
External device
RDA
RDB
SDA
SDB
RSA
RSB
CSA
CSB
SG
FG
SG
FG
FG
Signal name
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
Terminal resistor
R
R
R
R
R
Link operation
SDA
SDB
RDA
RDB
SG
FG
SDA
SDB
RDA
RDB
SG
FG
SDA
SDB
RDA
RDB
SG
FG
SD
RD
SD
RD
External device
C24 1) C24 2)
C24n
RS-422/485
cable
RS-422/485
cable
RS-232
(b) Connecting an external device and the module using RS-485
Terminal resistor
R
R
R
SDA
SDB
RDA
RDB
SG
FG
SDA
SDB
RDA
RDB
SG
FG
External device C24 1) C24 2)
C24n
RS-422/485
cable
RS-422/485
cable
SDA
SDB
RDA
RDB
SG
FG
R
R
SDA
SDB
RDA
RDB
SG
FG
RS-422/485
cable