Omron NT631 Operation Manuals page 112

Connecting to the Host's RS-232C Port
Connecting an NT631/NT631C and NT-AL001 (RS-422A)
104
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.
NT631/NT631C
RDA NT631/NT631C side
TRM
RDB
RS-422A
SDA
/485
terminal
SDB
block
RSA
RSB
24V
+DC
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
Abbreviation
RDA (−)
TRM
RDB (+)
SDA (−)
SDB (+)
RSA (−)
RSB (+)
Shielding wire
Functional
ground
Next PT
Section 5-1
Host
NT-AL001 side
Pin number Abbreviation
6 RDA (−)
RS-422A
5 RDB (+)
terminal
4 SDA (−)
block
3 SDB (+)
Functional
1
ground
8
7
6
5
4
3
2
1