Omron NT31 Operation Manuals page 116

Connecting to the Host's RS-232C Port
Connecting an NT31/NT31C and NT-AL001 (RS-422A)
The relay terminal board is not included in the figure below. Insert a relay terminal
board so as to achieve the wiring configuration indicated below.
NT31/NT31C
1
14
13 25
In order to avoid an FG ground loop, do not make the connections between the
functional ground of the NT-AL001 and the shielding.
NT-AL001
RS-422A
NT31/NT31C side
Abbreviation Pin number
Shielding wire
Connector
FG
hood
−
1
SD 2
RS-232C/
422A/485
RD 3
connector
RS 4
CS 5
−
6
SG 7
−
8
9
TRM
RDB (+) 10
RDB (+) 11
−
12
−
13
−
14
SDA (−) 15
RDA (−) 16
−
− −
RSB (+) 23
24
RSA (−)
−
25
(25-pin type)
Next PT
Section 5-1
Host
7
5
3
1
NT-AL001 side
Pin number Abbreviation
6 RDA
RS-422A
5 RDB
terminal
4 SDA
block
3 SDB
Functional
1
ground
8
6
4
2
105