Omron NT31 Operation Manuals page 150

Connecting to the Host's RS-422A/485 Port
5-2-4 1:N Connection among RS-422A Ports
Reference: Communication using the RS-422A type NT link (1:N) method is possible when a
1
14
RS-232C/
422A/485
connector
13 25
In order to avoid an FG ground loop, do not connect the functional ground of the
NT31/NT31C to the shielding of the RS-422A cable.
The connection method in which the RS-422A ports of multiple NT31/NT31Cs and
one host are connected in a 1:N connection is described here.
24V
DC PRINTER PORT B
serial communication board is installed at CS1 series CS1G/H, and when a com-
munication board is installed at the C200HX/HG/HE (–ZE).
NT31/NT31C side
Abbreviation Pin number
Connector
FG
hood
−
1
SD 2
RD 3
RS 4
CS 5
−
6
Shielding wire
SG 7
−
8
TRM 9
RDB (+) 10
SDB (+) 11
−
12
−
13
−
14
SDA (−) 15
RDA (−) 16
−
− −
RSB (+) 23
RSA (−) 24
−
25
(25-pin type)
NT31/NT31C
Serial port B
(RS-422A, 25-pin type)
25-pin connector
Relay terminal block
Max. 2 m
RS-422A cables
(max. total length 500 m)
PC (CPU) side
Pin number Abbreviation
Connector
FG
hood
1 SDA (−)
RS-422A
connector
2 SDB (+)
−
3
−
4
−
5
6 RDA (−)
−
7
8 RDB (+)
−
9
(9-pin type)
CPU
C200HX/HG/HE(-ZE)
9-pin connector
Section 5-2
6
1
9
5
139