Siemens SIMATIC NET PROFIBUS - Manual (Page 43)

Topologies of SIMATIC NET PROFIBUS Networks
2-17
PROFIBUS Networks SIMATIC NET
6GK1970-5CA20-0AA1 Release 2 05/2000
2.4 Topologies with PROFIBUS-PA
Bus and Star Topology
With PROFIBUS-PA, the topology can be either a bus or star.
SpliTConnect System
The SpliTConnect tap (T tap) allows the structuring of a bus segment with DTE
attachment points. The SpliTConnect tap can also be cascaded with the
SpliTConnect coupler to form attachment distributors. Using the SpliTConnect
terminator, the tap can be extended to become the segment terminator.
PROFIBUS-DP
PROFIBUS-PA
24 V DC
DP/PA coupler
(bus terminator
integrated)
Distributor made
up of T taps
Bus
T tap
Star
Main cable
Tap line
T tap with
integrated
bus terminator
Tap line
Field devices attached
via M12 connector
Figure 2-11 Bus and Star Topology
Field Device Power Supply via PROFIBUS-PA
When using the DP/PA bus coupler, the power for the field devices is supplied via
the data line of PROFIBUS-PA.
Design
The total current of all field devices must not exceed the maximum output current
of the DP/PA coupler. The maximum output current therefore limits the number of
field devices that can be attached to PROFIBUS-PA.