3.3.2. STAR-TYPE CONNECTION FOR 2-WIRE RS485 BUS
Using the ADA-1044H, configured for operating with 4-ports, 2-wire RS485 (the '
RS-485 PORTS'
switch should be set in 2W position
and '
SW1”
switch should be set in RS485 position), it is possible to make :
- star-type connection of up to 128 devices with 2-wire RS485 interface,
- galvanic separation of RS232 port from RS485 Bus.
During the connecting, pay attention to the proper implementation of the connection according to the following drawings.
Fig 7. Star-type connection of devices with 2-wire RS485 interface
8
ADA-1044H
-
-
A
B
A
B
GND
Rt
S
LA
V
E
-6
5
S
LA
V
E
-6
6
S
LA
V
E
-1
28
...
S
e
g
m
en
ts
o
f
4x
R
S
48
5
(2
W
)
b
u
s
-
-
A
B
GN
D
A
B
GN
D
Rt
S
L
A
V
E
-2
...
S
L
A
V
E
-3
2
-
-
A
B
GN
D
S
L
A
V
E
-1
-
-
-
-
A
B
GND
-
-
GND
-
-
A
B
GN
D
A
B
GN
D
Rt
S
LA
V
E
-2
...
S
LA
V
E
-3
2
-
-
RS
485
(2W)
co
nn
ect
or
A
B
GN
D
S
LA
V
E
-1
-
-
-
-
A
B
RS485(2W)
connector
A
B
GND
Rt
S
LA
V
E
-3
3
S
LA
V
E
-3
4
S
LA
V
E
-6
4
...
-
-
A
B
GND
-
-
GND
RS
485
(2W)
co
nn
ect
or
RS
485(
2W)
con
nec
to
r
RS
485(
2W)
con
nec
to
r
RS
485
(2W)
co
nn
ect
or
RS
485(
2W)
con
nec
to
r
RS485(2W)
connector
RS485(2W)
connector
RS485(2W)
connector
RS485(2W)
connector
RS485(2W)
connector
C
T
S
-
7
R
T
S
-
8
G
N
D
-
5
T
x
-2
R
x
-3
D
S
R
-
4
D
T
R
-
6
R
2+
/A
4
R
2-
/B
4
T
2+
/A
3
T
2-
/B
3
R
t
R
t
V
ss
+
V
ss
-
V
ss
-
V
ss
+
R
1+
/A
2
R
1-
/B
2
T
1+
/A
1
T
1-
/B
1
R
t
R
t
A
D
A
-1
04
4H
R
S
23
2
co
n
n
ec
to
r
R
S
48
5/
42
2
co
n
n
ec
to
r
P
o
w
er
S
u
p
p
ly
