Omron NT631C manual Connecting to the Host’s RS-422A/485 Port, Rda

Connecting to the Host’s RS-422A/485 Port Section 5-2

Reference: • The internal circuit of the NT631/NT631C is shown below.

-	RDA	Making a connection here inserts a terminator between
	Terminal resistor (120 Ω)	+ (RDB) and - (RDA).
	TRM
+	RDB

•For details on setting the terminal resistance of NT-AL001, refer to Set- tings at the RS-232C/RS-422A Adapter (NT-AL001)(page 81).

5-2 Connecting to the Host’s RS-422A/485 Port

The methods for connecting the RS-422A/485 port of the NT631/NT631C and the RS-422A/485 port of the host are described here. There are the following methods.

The following discussion is focused on the connection method to OMRON PLCs (By using the memory link method, a connection can be made to any arbitrary RS-422 unit). When making a connection to a host other than OMRON PLCs, refer to the PLC Connection Manual (V042-E1-@) or Multi Vendor Connection Manual (V060-E1-@).

•Method in which the RS-422A ports of the NT631/NT631C and host are connected directly by an RS-422A cable (page 115).

When this method is used, the cable length can be extended up to 500 m.

PT Host

RS-422A cable (max. 500 m)

•Method in which the RS-485 ports of the NT631/NT631C and host are connected by an RS-485 cable (page 118).

When this method is used, the cable length can be extended up to 500 m.

This connection method can be used only with the NT Link (1:N) meth- od (standard or high-speed) of type RS-485.

PT Host

RS-485 cable (max. 500 m)

•Method in which the RS-422A ports of multiple NT631/NT631Cs and the RS-422A port of the host are connected in a 1:N connection (page 119).

This connection method is used with the RS-422A NT Link (1:N) meth- od (standard or high-speed).

PT Host

RS-422A cable

(max. total length 500 m)

•Method in which the RS-485 ports of multiple NT631/NT631Cs and the RS-485 port of the host are connected in a 1:N connection (page 121).

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