Mitsubishi MELSEC LJ71C24, User Manual

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6 SETTING AND WIRING
6.3 External Wiring with RS-422/485 Interface
This section explains the specifications of RS-422/485 and how to connect them with
external devices.
6.3.1 RS-422/485 terminal block specifications
The following shows the specifications of the RS-422 connector and RS-422/485
terminal block that connect to an external device.
Mnemonic Signal name
Signal direction
C24 External device
SDA
SDB
RDA
RDB
SG
FG
FG
Send data (+)
Send data (–)
Receive data (+)
Receive data (–)
Signal ground
Frame ground
Frame ground
SG
SDA
SDB
RDA
RDB
LJ71C24
(FG)
(FG)
(1) The following describes the control signals.
1) SDA, SDB signals
These are signals to send data from the C24 to the external device.
2) RDA, RDB signals
These are signals for the C24 to receive data from the external device.
(2) Terminating resistor
Connect the termination resistor referring section 6.3.3.
(3) Suitable crimp-on terminals
Use 1.25-3 for the solderless terminal to be attached on the terminal block.
Use the UL certified crimp-on terminal. For crimping the terminal, use the tools
recommended by the crimp-on terminal manufactures. Crimp-on terminals with
insulation sleeves cannot be used.
(4) Tightening torque
For details on the tightening torque for the RS-422/485 terminal block, refer to
Section 6.1.1.