Omron NT631 Operation Manuals page 115

Connecting to the Host's RS-232C Port
Connection between NT631/NT631C Units (RS-485)
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
RS-485
:
RDA
TRM
RDB
SDA
SDB
RSA
RSB
24V
+DC
* Short TRM and RDA terminals of the NT631/NT631C at the end of the RS-485 cable
( marked in the above figure) using the short-circuit tool supplied with the
:
NT631/NT631C.
In order to avoid an FG ground loop, make the connection between the connector
hood and the shielding at the one side only.
NT631/NT631C side
Short-circuit tool
Abbreviation
:
RDA (−)
TRM
RS-422A
RDB (+)
/485
SDA (−)
terminal
block SDB (+)
RSA (−)
RSB (+)
Functional
ground
Shielding wire
Section 5-1
Host
NT631/NT631C side
Abbreviation
RDA (−)
TRM
RS-422A
RDB (+)
/485
SDA (−)
terminal
SDB (+) block
RSA (−)
RSB (+)
Functional
ground
RDA
TRM
RDB
SDA
SDB
RSA
RSB
24V
+DC
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