Omron CP1H CPU Operation Manual page 722

Connections to Serial Communications Option Boards
• If the I/O wiring and power cables must be placed in the same duct, they must be shielded from each other
using grounded steel sheet metal.
PLC power supply
and general control
Communications
circuit wiring
cables
Ground to 100 Ω or less.
2-Wire and 4-Wire Connections
The transmission circuits for 2-wire and 4-wire connections are different, as shown in the following diagram.
Example of 4-Wire
Connections
2/4-wire switch
(DPDT)
Option Board
Note (1) Use the same transmission circuit (2-wire or 4-wire) for all nodes.
(2) Do not use 4-wire connections when the 2/4-wire switch on the Board is set to 2-wire.
NT-AL001 Link Adapter Settings
The NT-AL001 Link Adapter has a DIP switch for setting RS-422A/485 communications conditions. When con-
necting the Serial Communications Option Board, refer to the DIP switch settings shown in the following table.
Pin
1 Not used. Always set this pin to ON.
2 Built-in terminating resistance setting
ON: Connects terminating resistance.
OFF: Disconnects terminating resistance.
3 2/4-wire setting
2-wire: Set both pins to ON.
4
4-wire: Set both pins to OFF.
5 Transmission mode (See note.)
Constant transmission: Set both pins to OFF.
Transmission performed when CTS signal in RS-232C interface is at high level:
Set pin 5 to OFF and pin 6 to ON.
6
Transmission performed when CTS signal in RS-232C interface is at low level:
Set pin 5 to ON and pin 6 to OFF.
Note When connecting to a CP-series CPU Unit, turn OFF pin 5 and turn ON pin 6.
688
Power lines
Steel sheet metal
Other Unit
Other Unit
Function
200 mm min.
Example of 2-Wire
Connections
2/4-wire switch
(DPDT)
Other Unit
Not connected
Option Board
Appendix F
Other Unit
Factory setting
ON
ON
OFF
OFF
ON
OFF