Omron Programmable Terminals NT631C - Manual (Page 141)

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Connecting to the Host’s RS-422A/485 Port Section 5-2
*1
Crimp terminals of common use for M3 and M3.5
The terminal screws of the NT631/NT631C are M3.5 specification. When wir-
ing, use crimp terminals for M3.5 use. Tighten terminal screws with a tighten-
ing torque of 0.8 N
⋅m.
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.
Note 1. Make sure to tighten screws at the connectors after cable connection.
2. Always use crimp terminals for wiring at terminal blocks.
Examples of Applicable Terminals
• For M3.5
• For M3
5-2-7 Setting the Terminal Resistance for RS-422A/485
Communications
The serial port B connector of the NT631/NT631C 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 communications cable, but not at any other device.
The NT631/NT631C has a built-in terminal resistor, and whether or not the
terminal resistance is applied is set by shorting or opening the terminal resis-
tance setting terminals (TRM). The terminal resistance is 120
Ω.
When carrying out RS-422A/485 communications using serial port B, short
between terminals at the NT631/NT631C at the end of the RS-422A/485
cable. Leave these terminals open at NT631/NT631C 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.
Crimp ter-
minals 1.25-N3A
(fork type) *1 Japan Solderless
Terminal MFG Recommended cable size:
AWG22 to 18
(0.3 to 0.75 mm
2 ) Y1.25-3.5L (fork
type) *1 Molex Inc.
Name Model Maker Remarks
Fork type
7 mm max.
Round type
7 mm max.
Fork type
6.2 mm max.
Round type
6.2 mm max.
RDA
TRM
RDB
SDA
Short-circuit tool