Eaton XC-152 Series, Руководство пользователя, Страница: 56 / 86

5 External connections
5.4 Serial interfaces to other devices
52
Compact PLC XC-152 05/17 MN050001ZU EN www.eaton.com
5.4.2.2 RS485 topology
• A bus segment can interconnect up to 32 slaves.
• Multiple bus segments can be connected with the use of repeaters

(bi-directional amplifiers).
A bus segment must be provided with a cable termination (120

) at both
ends.

These terminations must be connected inside the plug, directly between

PIN 3 and PIN 7.
Figure 17: Bus termination RS485 Modbus
Figure 18:
Bus segment with four nodes
￫
The use of repeaters enables the maximum cable length to be
increased. For more details, please consult the documentation
for repeaters provided by manufacturer.
￫
The bus segment must be terminated at both ends.
No more than two terminations must be provided for each bus
segment.
Operation without correct cable termination can cause transmis-
sion errors.
PIN 6, 5 V
PIN 7, A A, +
450 - 650 Ω
PIN 3, B B, -
120 Ω
PIN 5, GND GND
450 - 650 Ω
1
2
3
6
7
5
4
8
9
120
1
2
3
6
7
5
4
8
9
120
1
2
3
6
7
5
4
8
9
1
2
3
6
7
5
4
8
9
GND
A
B
GND
A
B
GND
A
B
GND
A
B
GND
A
B
GND
A
B