Multiple switch-gear cabinets: If potential differences can occur between the switch-gear cabi-
nets, the capacitive earthing method is chose0n in order to avoid circulating currents on the
cable shields.
CS31
SHIELD
BUS 2
BUS 1
Slave
CS31−
SHIELD
BUS 2
BUS 1
Slave
120 Ω
CS31−
BUS 1
BUS 2
SHIELD
Slave
PE
PE
PE
COM1
1
5
6
9
120 Ω
270 Ω
pull−up
270 Ω
pull−
CS31
Master
1
2
3
5
4
2
down
Fig. 209: Earthing concept with several switch-gear cabinets: direct earthing of cable shields
when cables enter the first switch-gear cabinet (containing the master), and capacitive earthing
at the modules
1 Cabinet 1
2 Cabinet earthing
3 Direct earthing with clip or steel plate
4 Cabinet 2
5 Capacitive earthing with 0.1 µF X-type capacitor directly on the cabinet steel plate
Everywhere is valid: The total length of the earthing connections between the shield of the Ter-
minal Base and the earthing bar must be as short as possible (max. 25 cm). The conductor
cross section must be at least 2.5 mm².
VDE 0160 requires, that the shield must be earthed directly at least once per system.
2.5.4.5 Ethernet
Ethernet is also used for PROFINET, EtherCAT and Modbus TCP connection.
Case B
System Assembly, Construction and Connection
AC500-eCo > Connection and Wiring
2019/04/17 3ADR010121, 13, en_US 1217
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