Basic Documentation

BACnet networks with MS/TP trunks
Checklist for designing BACnet networks with MS/TP trunks
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This is a good point to refer once again to the two system limits to complete the concept:
Command process Designing a system
Distribution/commanding of group masters to group member Restricted to max. 500 group members
Collect data Designing a system
Collecting data from the group members via the group master Restricted to max. 250 group members
5.3 Checklist for designing BACnet networks with MS/TP
trunks
Small to mid-sized project
Consider the following questions for detailed planning when designing a small to mid-sized project with a
low level of network complexity:
Question Designing the BACnet network Designing the IP network
Is the number of Desigo room automation
stations < 500?
One BACnet network Small to mid-size project and networks
of a lower complexity
Does the number of primary plants,
implemented with Desigo PXC, < 200?
One BACnet network
Are only HVAC and Desigo room automation
stations planned on this project?
For lighting and blinds controls, see
Section Network topology in the manual
Desigo room automation engineering,
mounting and installation
(CM111043)
Is the number of Desigo room automation
stations on a flow (MS/TP segment) > 64?
Segments over multiple
BACnet MS/TP IP routers
Are multiple BACnet MS/TP IP routers used? An IP network can include a max. 8
BACnet MS/TP IP routers and max. 250
DXR2.M devices.
Are BACnet third-party devices used? Own UDP port
Does data exchange need to be implemented
between BACnet third-party devices and Desigo
units (PXC)?
Same UDP port
Do you anticipate commanding more than 500
group member on central functions (emergency,
service, or protection functions or operating
modes and set points for lighting, blinds, HVAC,
fire and wind, etc.)?
No → OK
The central functions need to be divided
up for more than 500 group members.
A group member is not the same as a
room segment.
A room segment can include lots of
group members.
Do you anticipate more than 250 group
members on central functions that supply
demand signals to supply plants?
A cooling or heating valve sends out a demand
signal. A room segment can send out multiple
demand signals.
No → OK