ABB AC500 PLC Hardware Manual page 1215

Bus Topology A CS31 bus always contains only one bus master (CPU or Communication Module) which con-
trols all actions on the bus. Up to 31 slaves can be connected to the bus, e. g. remote modules
or slave-configured CPUs. Besides the wiring instructions shown below, the wiring and earthing
instructions provided with the descriptions of the modules are valid additionally.
270 Ω
pull−up
120 Ω
270 Ω
pull−down
Fig. 204: Bus topology for a CS31 bus at COM1 (Master is at the end of the bus line)
1 Master at the bus line end, pull-up and pull-down activated, bus termination with 120 Ω
resistors
2 Direct earthing with clip or steel plate
CS31
Slave
Fig. 205: Bus topology for a CS31 bus at COM1 (Master is within the bus line)
1 Master within the bus line, pull-up and pull-down activated
2 Direct earthing with clip or steel plate
2019/04/17
5
9
6
1
1
CS31
Slave
270 Ω
pull−up
270 Ω
120 Ω
pull−down
NOTICE!
Risk of malfunctions!
Spur lines are not allowed within the CS31 bus.
Loop the bus line from module to module.
3ADR010121, 13, en_US
System Assembly, Construction and Connection
AC500-eCo > Connection and Wiring
2
1
5
9
6
1
2
CS31
Slave
120 Ω
CS31
Slave
120 Ω
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