Omron Programmable Terminals NT31 NT31C - Manual (Page 133)

5-2 Section Connecting to the Host’s RS-422A/485 Port
122
C200HX-CPU65-ZE C200HX-CPU85-ZE
CQM1H-CPU51 CQM1H-CPU61
1
14
13 25
NT31/NT31C side
Shielding wire
(25-pin type)
Abbreviation
FG
−
SD
RD
RS
CS
−
SG
−
TRM
RDB (+)
SDB (+)
−
−
−
SDA ( −)
RDA ( −)
−
−
RSB (+)
RSA ( −)
−
Pin number
Connector
hood
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
−
23
24
25
RS-232C/
422A/485
connector
6
5 9
1
RS-422A
connector
Pin number
Connector
hood
1
2
3
4
5
6
7
8
9
Abbreviation
FG
SDA ( −)
SDB (+)
−
−
−
RDA ( −)
−
RDB (+)
−
(9-pin type)
PC (CPU) side
In order to avoid an FG ground loop, do not connect the functional ground of the
NT31/NT31C to the shielding of the RS-422A cable.
5-2-4 1:N Connection among RS-422A Ports
The connection method in which the RS-422A ports of multiple NT31/NT31Cs
and one host are connected in a 1:N connection is described here.
NT31/NT31C
25-pin connector
9-pin connector
Serial port B
(RS-422A, 25-pin
type)
CPU
RS-422A cables
(max. total length 500 m)
24V DC PRINTER PORT B
Max. 2 m
Relay terminal block
CS1G/H
C200HX/HG/HE(-Z)E
CQM1H