Basic Documentation

BACnet
/IP networks
Designing BACnet/IP networks
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Question Designing the BACnet network Designing the IP network
Are the control units for the primary plants
decentralized on individual floors together with
Desigo room automation stations?
Floor scope
The same UDP port for the Desigo
system
Floor scope with room automation on its
own VLAN
Are BACnet/Desigo devices together on a
separate BACnet network for building, plant,,
and floor scope?
Managed layer 2 switches, configuration
of VLAN, and eventually port mirroring
Are there Desigo room automation stations with
central functions?
Unmanaged layer 2 switch cabled in a
star topology
Are there Desigo room automation stations that
automate important and critical rooms?
Are the no more than 20 Desigo room
automation stations on the floor?
Cabling using daisy chain technology,
originated at a distribution switch
You must distinguish between important and less important room automation stations if
there are more than 20 Desigo room automation units on the floor. Starting at the
distribution switch, the cabling is either in a star topology or with a max. of 20 units as
daisy chain.
Are different IP networks and different UDP
ports configured?
One BBMD per IP segment is required
with an asymmetrical BDT. FDT must
also be possible if there is a Desigo CC
management platform or other BAC
clients.
Layer 3 switch
Large project
Consider the following questions for detailed planning when designing a large project with a high level of
network complexity:
Question Designing the BACnet network Designing the IP network
Are other disciplines (fire, intrusion, video)
planned on the project in addition to HVAC and
Desigo room automation?
Large project and network of high
complexity
Is the number of Desigo room automation
stations between 500 and 15,000?
Does the number of primary plants,
implemented with Desigo PXC, > 200?
Does building automation and control extend to
multiple properties, buildings, and building
sections?
Multiple BACnet internetworks,
eventually with multiple BACnet
networks.
See as well: Special case: BACnet
referencing over different IP networks
[➙ 44]
Do numerous properties and buildings required
a clearly structure IP network?
Layer 3 switches for implementing
multiple IP segments
Is IT security required? Implementation of relevant topics on
local or industry guidelines
4.2 Designing BACnet/IP networks
The following examples demonstrates network planning and configuring of a BACnet network up to
commissioning in the real world.
The examples illustrate the required clarifications and planning steps, the selection and configuration of
hardware components involved in implementing small to mid-sized, up to large Desigo projects.
We rely on products from the Siemens portfolio in the examples. The network components must meet the
same requirements and function if you can use existing IT infrastructure to implement the project.