Omron NT631C manual Standard or high-speed, RS-485 cable Max. total length 500 m

Connecting to the Host’s RS-422A/485 Port				Section 5-2
This connection method is used with the RS-485 NT Link (1:N) method
(standard or high-speed).
	PT		Host
		RS-485 cable
		(max. total length 500 m)

Note One end of the wire must always be connected to the host (PLC), and there must be no branching. Branching will cause problems such as transmission delays and communications failures.

	PLC	(At termination)
						Relay terminal block
							Max. 2 m
	NT631C		NT631		NT631			NT631
(Not at		(Not at						(At
termination)		termination)		(Not at				termination)
				termination)

NT631

PLC

NT631C NT631

PLC

Relay terminal block

NT631 NT631C NT631

Example of Good Connection Examples of Bad Connections

Reference: CS/CJ-series CPU Units cannot be connected with the 1:1 connection NT Link method. Use the 1:N connection NT Link method (standard or high- speed) instead to make the 1:1 connection. For details, refer to Using the NT Link (1:N) Method (page 106) or Using the High-speed NT Link (1:N) Method (page 108).

5-2-1 Host Types and Settings

The types of host that have an RS-422A port and can be connected to the RS-422A/485 port of the NT631/NT631C, and the settings to be made at the host, are described here.

When Using the Host Link Method

Compatible Host Units

Some models and series of OMRON PLCs have the RS-422A/485 host link function built in. With the CS/CJ-series and CQM1H, the host link method can be used by installing a Serial Communications Board/Unit. In addition, some C200HX/HG/HE(-Z)E CPU Unit can be connected in the host link method by installing a Communications Board.

With the CPM2A and CPM2C, an RS-422A of 1:1 NT Link can be created through a CPM1-CIF11 RS-422A Adapter.

Check the model and series of the PLC and the type of the installed Board or Unit before making a connection.

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