Omron NT31 Operation Manuals page 109

Connecting to the Host's RS-232C Port
Settings at the RS-232C/RS-422A Convertor Unit (NT-AL001)
98
When making a connection between RS-232C and RS-422A/485 ports using an
RS-232C/RS-422A convertor unit, set the DIP switches on the NT-AL001 as fol-
lows.
Example: the terminal resistor is active,
ON
1 2 3
Note Read the manual supplied with the NT-AL001 carefully before using the unit.
RS-422A, NT link (1:N).
4 5 6
Built-in terminal resistor setting (DIP SW1-2)
If at the end of the RS-422A/485 cable, set this switch to ON (to
activate the built-in terminal resistor).
If not at the end of the RS-422A/485 cable, set this switch to OFF
(to inactivate the built-in terminal resistor).
2-wire type/4-wire type selection (DIP SW1-3, SW1-4)
For RS-422A, set both of these switches to OFF (4-wire type).
For RS-485, set both of these switches to ON (2-wire type).
Selection of RS-422A/485 send mode (DIP SW1-5, SW1-6)
For host link or NT link (1:1), set both of these switches to OFF.
(Always send)
For NT link (1:N), set SW1-5 to OFF and SW1-6 to ON.
(Sends when CS is "H")
om on
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NT-AL001
Section 5-1