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MELSEC-Q
4 SETTINGS AND PROCEDURES PRIOR TO OPERATION
4.4.2 Connecting the RS-422/485 interface
The following shows the connection precautions and connection examples when using
the Q series C24 RS-422/485 interface.
(1) Connection precautions
(a) When connecting the Q series C24 SG and FG signals to the external
device, connect them according to the specifications of the external device.
(b) Connect the shield of the connection cable to the FG terminal on either of
the connected devices.
If normal data communication is not obtained due to external noise even if
wiring is made as shown above, perform wiring as follows:
1) Connect between the FG of both stations with the shield of the
connection cable.
On the external device side, however, follow the instruction manual of
the external device.
Be sure to use the plate terminals included with the product when
connecting the braided shield wire to the QJ71C24N-R4.
2) Connect the (FG) of the Q series C24 side to the FG terminal at the power
supply module of the station which has the Q series C24 is installed, or to
the FG terminal of the control panel on which the Q series C24 PLC is
installed.
3) Connect nnA and nnB of each signal in the connection cable as a pair.
Correspondance of the RS-422/485 terminal block and signal location.
Shield
Q series C24
External device
SDA
SDB
RDA
RDB
SG
(FG)
(FG)
SDA
SDB
RDA
RDB
SG
FG
SG
FG
FG
SDA
SDB
RDB
RDA