ABB AC500 PLC Hardware Manual page 1284

System Assembly, Construction and Connection
AC500 (Standard) > Connection and Wiring
Cables with PVC core insulation and a core diameter of 0.8 mm can be used up to a length of
ca. 250 m. In this case, the bus terminating resistor is ca. 100 W.
Cables with PE core insulation can be used up to a length of ca. 500 m.
2.6.4.8.3 Bus Topology
A CS31 system bus always contains only one bus master (CPU or communication module)
which controls 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.
120
Ohms
CS31 bus master
e.g. PM581
Master at the
bus line end,
pull-up and
pull-down
activated
bus termination
120 Ohms
Fig. 233: Bus topology for a CS31 system bus at COM1 (bus master at one end of the bus line)
Fig. 234: Bus topology for a CS31 system bus at COM1 (bus master within the bus line)
1284
1
COM1
2
3
4
direct earthing
with clip
on cabinet
steel plate
Master within
the bus line,
pull-up and
pull-down
activated
120
Ohms
CS31 system bus
CS31
slave
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
CS31 system bus
CS31
slave
1
COM1
2
CS31 bus master
3
e.g. PM581
4
direct
earthing
with clip
120
Ohms
CS31
slave
120
Ohms
CS31
slave
2019/04/17