Rs-485 Port Wiring - Omron S8AS User Manual

RS-485 Port Wiring

3-4

RS-485 Port Wiring

Wiring the RS-485
Port
Example Connection to a Host Computer
Computer
Name
CD
RD
SD
RS-232C ER
interface SG
DR
RS
CS
C1
Power Supply
• AC model:
100 to 240 VAC
• DC model:
24 VDC or 24 VAC
(50 to 60 Hz)
52
S8AS models with communications have an RS-485 port that can be con-
nected with a host computer or controller.
A (−) B (+)
• The connection format is 1:1 or 1:N. Up to 32 nodes can be connected to
a host computer.
• Insert a Cramp Filter (E04SR301334 manufactured by SEIWA) in the
cable as a countermeasure against noise.
Pin Pin
Name
1 1
2 2
3 3
4 4
5 5
6 6
7
8
9
• The node on each end of the transmission path, including the host com-
puter, must be specified as an end node (i.e., terminating resistor must be
connected.) Use terminating resistor of 120 Ω (1/2 W) with a combined
resistance of at least 54 Ω.
• Make sure that the communications specifications are set to the same
values for the host computer and the S8AS. (Refer to 4-1 Parameter
Table.) When connecting in a 1:N format, make sure that the communica-
tions specifications except for the communications unit number are set to
the same values for all nodes. A unique communications unit number
must be set for each node.
• Strip 10 mm from the ends of the RS-
485 cable's wires.
• Press the terminal's release button all
the way in and insert the wire into the
round wire hole. When the wire is
inserted, be sure that the wire conduc-
Press the Release
tor is not exposed.
Button all of the
way in and insert • Release the release button to lock the
the wire.
wire in place.
• After wiring, verify that the wires are
securely locked in the terminals.
K3SC-10
Name
Pin
PWR SG 7
NC RDA(−) 8
SG SDA(−) 9
PWR NC 10
SD 11
RDB(+)
RD SDB(+) 12
Section 3-4
S8AS
RS-485
A(−)
(See
note.)
B(+)
Clamp filter
We recommend
twisting the RS-485
(See
communications lines.
note.)
S8AS
A(−)
RS-485
B(+)
(See note.)
Note: Terminating resistor (120 Ω, 1/2 W recommended)