Setting The Terminal Resistance For Rs-422A/485 Communications - Omron NT31 Setup Manual

Connecting to the Host's RS-422A/485 Port
5-2-7 Setting the Terminal Resistance for RS-422A/485
Communications
Check the required parts and prepare them in advance.
Name
Connector XM2A-0901
Connector XM2S-0911
hood
XM2S-0911-E
Cable TKVVBS4P-03
Crimp ter- 1.25-N3A
minals (fork type)
Y1.25-3.5L
(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
terminal block.
Note Always use crimp terminals for wiring.
Examples of applicable terminals
The serial port B connector of the NT31/NT31C has a terminal resistance set-
ting terminal (TRM).
In RS-422A/485 communications, a terminal resistor must be set at the device
at the end of the communications cable, but not at any other device.
The NT31/NT31C has a built-in terminal resistor, and whether or not the ter-
minal resistance is applied is set by the wiring at the terminal resistance set-
ting terminals (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 PTs
other than the one at the end of the cable.
When not using RS-422A/485 communications, the terminal resistance set-
ting is ineffective.
In order to set the terminal resistance, wiring work is required at the cable's
connector: carry out the wiring correctly by referring to APPENDIX E Making
the Cable.
Model Maker
9-pin type
Made by OMRON
9-pin type
Made by OMRON
9-pin type
Made by JAE
Tachii Electric Wire
Co., Ltd.
Japan Solderless
Terminal MFG
Molex Inc.
Fork type
6.2 mm max.
Remarks
Delivered with the following Units:
CS/CJ-series CPU Units
C-series C200HS CPU Units
C200HX/HG/HE(-Z) CPU Units
CVM1/CV-series CPU Units
CV500-LK201
Delivered with the following Units:
C-series C200HS CPU Units
C200HX/HG/HE(-Z) CPU Units
CVM1/CV-series CPU Units
CV500-LK201
Delivered with the following Units:
CS/CJ-series CPU Units
---
Recommended wire size:
AWG22 to AWG18
2
(0.3 to 0.75 mm )
Round type
6.2 mm max.
Section 5-2
127