Omron NT20S-ST121B-EV3 User Manual page 46

Connecting Link Adapters and RS-422A Converters
Note
RS-422A/485 Terminal
Block
Block Diagram
DIP Switch Settings
Pin
number
1 Terminating resistance
2 Two-wire/four-wire method selec-
tion (See note 1.)
3 Two-wire/four-wire method selec-
tion (See note 1.)
4 Not used.
5 Selection of RS control for RD
(See note 2.)
6 Selection of RS control for SD
(See note 3.)
Note
The hood will have the same electrical potential as the connector on the other
end of the cable.
Signal
RDA–
RDB+
SDA–
SDB+
FG
SD
RS
CS
RD
ER
DR
SV
SG
FG
Function
With (at both ends of the commu-
nications path)
Two-wire method
Two-wire method
---
With RS control
With RS control
(1) Set pins 2 and 3 to the same setting. (ON for the two-wire method or OFF
for the four-wire method.)
(2) To prohibit echoback, set pin 5 to ON (with RS control).
SW.6
SW.3
SW.5
ON
Section 2-3
SDB(+)
SDA( -)
SW.2 SW.1
RDB(+)
RDA(-)
FG
OFF
Without
Four-wire method
Four-wire method
---
Without RS control (always ready
to receive)
Without RS control (always ready
to send)
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