Omron NT31 NT31C manual 128

Connecting to the Host’s RS-422A/485 Port				Section 5-2
	Name	Model	Maker	Remarks
			25-pin type	Delivered with the following
		XM2S-2511		units:
			Made by OMRON
				C500-LK203
	Connector
				Delivered with the following
	hood
			25-pin type	units:
		DB-C2-J9
			Made by JAE	3G2A6-LK201-EV1
				3G2A5-LK201-EV1
	Cable	TKVVBS4P-03	Tachii Electric
			Wire Co., Ltd.
		1.25-N3A	Japan Solderless	Recommended cable size:
	Crimp	(fork type)	Terminal MFG
				AWG22 to 18
	terminals	Y1.25-3.5L
			Molex Inc.	(0.3 to 0.75 mm2)
		(fork type)

The terminal screws of the RS-422A adaptor (CPM1-CIF11) are M3 specifica- tion. When wiring, use crimp terminals for M3 use. Tighten terminal screws with a tightening torque of 0.5 N@m.

Use the same specification of the terminal screws which is used in the relay ter- minal block.

Note Always use crimp terminals for wiring.

Examples of applicable terminals

Fork type

6.2 mm or less

Round type

6.2 mm or less

5-2-7 Setting the Terminal Resistance for RS-422A/485 Communications

The serial port B connector of the NT31/NT31C has a terminal resistance setting terminal (TRM).

In RS-422A/485 communications, a terminal resistor must be set at the device at the end of the communication cable, but not at any other device.

The NT31/NT31C has a built-in terminal resistor, and whether or not the terminal resistance is applied is set by the wiring at the terminal resistance setting termi- nals (pins No. 9 and 10 of serial port B). The terminal resistance is 120 Ω. When carrying out RS-422A/485 communications using serial port B, short between terminals No. 9 and 10 at the NT31/NT31C at the end of the RS-422A/485 cable. Leave terminals No. 9 and 10 open at NT31/NT31C units other than the one at the end of the cable.

When not using RS-422A/485 communications, the terminal resistance setting is ineffective.

In order to set the terminal resistance, wiring work is required at the cable’s con- nector: carry out the wiring correctly by referring to APPENDIX E Making the Cable, page 267.

Abbreviation	Pin number
FG	Connector
	hood
-	Terminal resistor setting
-
	-
TRM	9
RDB (+)	10
SDB (+)	11
-	12
-
	-
-	25

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