Omron NT31 Operation Manuals page 151

Connecting to the Host's RS-422A/485 Port
Connecting between NT31/NT31C Units
1
13
140
The relay terminal block is not included in this figure. Insert the relay terminal block
so as to achieve the wiring configuration shown below.
NT31/NT31C
RS-422A
:
14
NT31/NT31C side
Abbreviation Pin number
Connector
FG
−
RS-232C/
SD
422A/485
connector
RD
RS
CS
−
SG
−
TRM
RDB (+)
RDB (+)
−
−
−
25
SDA (−)
RDA (−)
−
−
RSB (+)
RSA (−)
−
(25-pin type)
* Make the connection between pin numbers 9 and 10 at the NT31/NT31C at the end
of the RS-422A cable (marked "
In order to avoid an FG ground loop, connect the functional ground of only one of
the NT31/NT31C units to the shielding of the RS-422A cable.
Shielding wire
hood
1
2
3
4
5
6
7
8
:
9
10
11
12
13
14
15
16
−
23
24
25
" in the figure above) only.
:
Section 5-2
Host
1
NT31/NT31C side
Pin number Abbreviation
Connector
FG
hood
−
1
RS-232C/
2 SD
422A/485
connector
3 RD
4 RS
5 CS
−
6
7 SG
−
8
9 TRM
10 RDB (+)
RDB (+)
11
−
12
−
13
−
14
13
15 SDA (−)
16 RDA (−)
− −
−
23 RSB (+)
24 RSA (−)
−
25
(25-pin type)
14
25