3.3.4. LINE TERMINATION
The application of Line Termination (terminator) Rt = 120 ohms will reduce electrical reflection in data line at high baud rate. It is not
needed below 9600Bd. Line Termination resistor should be used if the distance is over 1000m @ 9600Bd or 700m @ 19200Bd
transmission. Example connection of Rt are shown on Fig. 6 & 7. Two resistors Rt =120
W
, 5%, 0,25W are supplied with ADA-4021
converter, free of charge.
3.4. CONNECTION OF CURRENT LOOP INTERFACE DEVICE
Figures 6, 7 & 8 show connection of SLAVE device Current Loop interface to ADA-4020.
3.5. CONNECTION TO CURRENT LOOP BUS OF DEVICES WITH RS485/RS422 INTERFACE
Fig 9. Example connection of the ADA-4020 converters to Current Loop bus
9
ADA-4020
G
N
D
C
u
rr
e
n
t
L
o
o
p
N
et
w
o
rk
M
A
S
T
E
R
R
S
4
85
D
e
v
ic
e
R
t
R
t
R
x+
R
x-
T
x+
/
A
T
x-
/
B
R
S
4
85
(2
W
)
S
L
A
V
E
-2
R
S
48
5
S
L
A
V
E
-1
5
R
S
48
5
Tx+ / A
Tx- / B
Rx+
Rx-
RS485 / RS422
connector
ADA-4020-1-1-11-2-3
SLAVE-PP-1
S
L
A
V
E
-1
R
S
48
5
R
S
4
22
R
S
4
85
(4
W
)
Rx+
Rx-
Rx+*
Tx+
Tx-
R
x-
T
x-
G
N
D
R
x+
R
x+
*
T
x+
Tx+ / A
Tx- / B
Rx+
Rx-
RS485 / RS422
Screw terminal
Rx+
Rx-
Rx+*
Tx+
Tx-
Tx+ / A
Tx- / B
Rx+
Rx-
Rx+
Rx-
Rx+*
Tx+
Tx-
Tx+ / A
Tx- / B
Rx+
Rx-
Tx+ / A
Tx- / B
Rx+
Rx-
Tx+ / A
Tx- / B
Rx+
Rx-
RS485 / RS422
connector
T
x+
/
A
T
x-
/
B
R
x+
R
x-
R
t
R
t
A
D
A
-4
02
0
-1
-1
-1
2
-2
-3
M
A
S
T
E
R
-P
P
ADA-4020-1-1-11-2-3
SLAVE-PP-2
ADA-4020-1-1-11-2-3
SLAVE-PP-15
RS485 / RS422
connector
RS485 / RS422
connector
RS485 / RS422
Screw terminal
RS485 / RS422
Screw terminal
Current Loop
Screw terminal
Current Loop
Screw terminal
Current Loop
Screw terminal
R
S
48
5
/
R
S
42
2
S
cr
e
w
t
er
m
in
a
l
C
u
rr
e
n
t
L
o
o
p
S
cr
e
w
t
er
m
in
a
l
R
S
48
5
/
R
S
42
2
te
rm
in
al
