Siemens SPC3 - Example for the RS 485 Interface

PROFIBUS Interface Center SPC3
Page 58 V1.3 SPC3 Hardware Description
2003/04 Copyright (C) Siemens AG 2003. All rights reserved.
9.2 Example for the RS 485 Interface
SN65ALS1176
1
1
2
U+
EN1
GND
EN2
1 0 0 K
1 0 0 K
2P5
2M
6
8
n
2P5
2M
6
8
0
R
1
K
2
IN
U-
U+
U-
U+
68n
68n
EN
2M
P5 P5
680R
1 K 2
O
U
T
EN
680R
300R
680R
HCPL0601
2P5
&
2
7
4
H
C
1
3
2
3
0
0
R
U+
IN
U-
3
0
0
R
6
8
n
6
8
n
6
8
0
R
O
U
T
EN
U-
U+
20K
M
M
2P5 2M
3
0
0
R
M
C
T
S
R
T
S
T
X
D
R
X
D
B
-
l
i
n
e
R
T
S
2
M
2
P
5
A
-
l
i
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e
I
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p
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r
t
a
n
t
:
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P
5
a
n
d
2
P
5
S
h
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d
D
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t
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>
2
V
1
2
3 4
6 7
8
9
L
a
y
o
u
t
:
l
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n
e
s
m
u
s
t
b
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.
M
1
M
HCPL7101 / 7721 / 0721
2
.
2
.
.
2
2
n
F
5
0
0
V
HCPL7101 / 7721 / 0721
5
Explanations of the circuitry:
The bus driver input EN2 has to be connected to low potential to ensure that after transmission of a
telegram the ASIC is able to listen to the transmitted data.
To minimize the capacity of the bus lines the user should avoid additional capacities. The typical capacity of
a bus station should be 15 ... 25 pF.