6-2
6-2 Wiring Method
6-2-1 When RS-485 is used (2-wire)
To make a 2-wire system, as shown in the figure below, 4) and 9) as well as 3) and 8) are short-circuited in the connector,
and 1) (SDB), 2) (SDA) and 5) (SG) are used to connect to external devices.
General purpose communication module
External device
to the next external device
SDA (+) 2)
SDB (-) 1)
SG 5)
SDA (+) 4)
SDB (-) 3)
RDA (+) 9)
RDB (-) 8)
FG 6)
(+)
(-)
SG
(Note)
Pin No.
In order to obtain the proper shielding effect, the
shielding wire needs to extend in the connector
cover and be connected properly to the terminal.
* To set a terminating resistor for a 2-wire system, change the "RS-485 Terminating resistor ON/OFF" switch to "1"(left
side when facing the front panel).
6-2-2 When RS-485 is used (4-wire system)
To make a 4-wire system, 1), 2), 5), 8) and 9) are used as in the figure below:
* To set a terminating resistor for 4-wire system, change
the "RS-485 Terminating resistor ON/OFF" switch to "3"
(left and right side when facing the front panel).
General purpose communication module
External device
to the next external device
SDA (+) 2)
SDB (-) 1)
SG 5)
SDA (+) 4)
SDB (-) 3)
RDA (+) 9)
RDB (-) 8)
FG 6)
RDA (+)
RDB (-)
SG
(Note)
SDA (+)
SDB (-)
Pin No.
In order to obtain the proper shielding effect, the
shielding wire needs to extend in the connector
cover and be connected properly to the terminal.
Note: Precaution when there is no SG terminal on the external device
SG wire cannot be connected if there is no SG terminal on the external device. Depending on the ambient environment, in
the worst, module internal element might be damaged. To avoid this, connect a Zener diode (of 6 V Zener voltage, RD6.2F
from NEC or equivalent) between signal cable and SG terminal in the connector on this module side.
When 2-wire
When 4-wire
SDA (+) 2)
SDB (-) 1)
SG 5)
RDA (+) 9)
RDB (-) 8)
* RS1, RS4 V2738 or later version has built-in zener
diode.
RS5 has zener diode.
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