Switches - Omron CQM1H-SCB41 Operation Manual

Component Names and Functions
Internal Circuits
Receiver
Driver
!Caution Confirm polarities before connecting RS-422A/485 cables. Some devices
Applicable Connectors
Recommended Cables
2-1-4

Switches

Terminating Resistance
Switch
2-Wire or 4-Wire Switch
The internal circuits for port 2 are shown below.
require that SDA/B and RDA/B or signal polarities be reversed.
Socket: XM2A-0901 (OMRON) or equivalent
Hood: XM2S-0911-E (OMRON, conforms to ESD) or equivalent
One Socket and one Hood are provided for each port.
CO-HC-ESV-3P 7/0.2 (Hirakawa Hewtech Corp.)
Cable length: 500 m max.
(The total combined cable length is 500 m max. T-branch lines must be a
maximum of 10 m long.)
The TERM and WIRE switches are on the front panel of the Serial Communi-
cations Board. Refer to page page 10 for a diagram of the Board.
When an RS-422/485 port is used, turn ON the switch if the Serial Communi-
cations Board is on the end of the transmission line. Refer to information on
specific serial communications modes for the ON/OFF settings.
Label
TERM Terminating
resistance switch
When an RS-422/485 port is used, set the switch to 2 when 2-wire connec-
tions are used, and set the switch to 4 when 4-wire connections are used.
Label
WIRE 2-wire or 4-wire
switch
Note Host Link, no-protocol, and 1:1 Data Link modes cannot use 2-wire RS-422A/
485 communications. Always use 4-wire connections when using RS-422A/
485 communications for these serial communications modes. Refer to 2-3
Wiring for connections.
Terminating resistance: 200
Terminating resistance switch
2-wire/4-wire switch
Name Settings
OFF: Terminating resistance
OFF
ON: Terminating resistance
ON
Name Settings
2: 2-wire
4: 4-wire
Section 2-1
Pin 8: RDB (+)
Pin 6: RDA ( )
Pin 2: SDB (+)
Pin 1: SDA ( )
Factory setting
OFF: Terminat-
ing resis-
tance OFF
Factory setting
2: 2-wire
13