Eaton XC-152 Series, Руководство пользователя, Страница: 61 / 86

5 External connections
5.4 Serial interfaces to other devices
Compact PLC XC-152 05/17 MN050001ZU EN www.eaton.com
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5.4.4.2 Profibus topology
• A bus segment can interconnect up to 32 slaves.
• Multiple bus segments can be connected with the use of repeaters (bi-
directional amplifiers).
Only use bus connector plugs specified for use with PROFIBUS networks.
These plugs combine both bus cables on a single node and ensure that the
cable shield has a low-impedance connection to the node's shield reference
potential. These bus terminal connectors contain the PROFIBUS cable termi-
nation that can be switched on as required.
A bus segment must be provided with cable termination at both ends. This
termination is passive, but is fed from the node. It ensures a defined quies-
cent signal on the bus if no bus station is sending. These bus terminations
are preferably implemented externally in the connector housing as per the
PROFIBUS standard (and can be implemented using the aforementioned bus
connector plugs).
Figure 20: Profibus bus segment with four nodes
￫
The use of repeaters enables the maximum cable length to be
increased.
Repeaters can also be used for galvanic isolation. For more
details, please consult the documentation for repeaters pro-
vided by manufacturer.
Make sure to follow the recommendations provided by CiA
(CAN in Automation) at http://www.can-cia.org.
￫
The bus segment must be terminated at both ends.
No more than two terminations must be provided for each bus
segment.
At least one of the two terminations must be fed by the bus
user.
Operation without correct termination of the Profibus network
can cause transmission errors.
1
2
3
6
7
5
4
8
9
390
390
1
2
3
6
7
5
4
8
9
1
2
3
6
7
5
4
8
9
1
2
3
6
7
5
4
8
9
M5EXT
(GND)
A
B
M5EXT
(GND)
A
B
M5EXT
(GND)
A
B
M5EXT
(GND)
A
B
M5EXT
(GND)
A
B
M5EXT
(GND)
A
B
220
220
390
390