1:N Connection Among Rs-485 Ports - Omron Programmable Terminals NT631 Setup Manual

Connecting to the Host's RS-422A/485 Port
5-2-5

1:N Connection among RS-485 Ports

Reference:
C200HX-CPU65-ZE/85-ZE
CQM1H-CPU51/61
Note A Serial Communications Board cannot be installed.
NT631/NT631C side
RDA
Abbreviation
TRM
RDA (-)
RDB
TRM
RDB (+)
SDA
RS-422A/
SDA (-)
485
SDB interface
SDB (+)
RSA (-)
RSA
RSB (+)
Functional
RSB
ground
24V
+DC
For details on handling shield wires, refer to 5-2-8 Handling the Shield on RS-
422A/485 Cables on page 125.
The connection method in which the RS-485 ports of multiple NT631/
NT631Cs and one host are connected in a 1:N connection is described here.
NT631/NT631C
NT631/NT631C
NT631/NT631C
• Communications using the RS-485A standard NT link (1:N) method is
possible only when a Serial Communications Board is installed in a CS-
series PLC, a Serial Communications Unit is installed in a CS/CJ-series
PLC, a Communications Board is installed in a C200HX/HG/HE(-Z)E, or a
CQM1H-SCB41 Serial Communications Board is installed in a CQM1H.
• Communications using the RS-485A high-speed NT link (1:N) method is
possible only when a Serial Communications Board is installed in a CS-
series PLC or a Serial Communications Unit is installed in a CS/CJ-series
PLC.
PLC side
Pin number Abbreviation
Shielding wire
Connector
FG
hood
1 SDA (-)
2
SDB (+)
−
3
−
4
−
5
6
RDA (-)
−
7
8 RDB (+)
9 −
Next PT
(9-pin type)
RS-485 cables
(max. total length 500 m)
Serial port B
(RS-422A/485, terminal block)
Section 5-2
1
RS-422A
interface
5
CPU Unit
CS/CJ-series or
C200HX/HG/HE(-Z)E
PLC
9-pin connector
121
6
9