User Manual

Network architecture
BACnet architecture (MLN & ALN)
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Key
B Bridge, e.g., IP router, LonWorks router
R Repeater, e.g., LonWorks physical repeater
RT Router, e.g., PXG3
½
RT Half router, e.g., PX..-T
In BACnet, the BACnet internetwork is defined as the largest BACnet unit. It
consists of one or more BACnet networks. Only one active connection can exist
between any two BACnet devices in a BACnet internetwork.
All bus subscribers from the ALN and MLN, including BACnet third-party
devices, are part of the BACnet internetwork. The devices in the FLN are part of
the Desigo system but not part of the BACnet internetwork, because they do
not communicate via BACnet.
Desigo devices use LonTalk (BACnet/LonTalk), IP (BACnet/IP) or MS/TP
(BACnet MS/TP) as their transport protocol. If different transport protocols are
used, different physical networks are created, which must be connected to the
PXG3 router. BACnet routers connect networks on the BACnet network layer
and transmit messages via the network number.
If the transport protocol changes, the BACnet network also changes, e.g.,
BACnet devices that use LonTalk as their transport protocol are always located
in a different network than devices that use IP as their transport protocol. This
also applies to PTP connections.
Desigo devices use LonTalk (BACnet/LonTalk) or IP (BACnet/IP) as their
transport protocol and MS/TP (BACnet MS/TP) to integrate third-party
devices. If different transport protocols are used, different BACnet networks are
automatically created, which must be connected to the PXG3 BACnet router.
Multiple BACnet internetworks can be created on an IP segment by using
different UDP port numbers.
Desigo establishes PTP connections only between operator units and a
network. Operator units duplicate a virtual network since PTP connections
demand a network at both ends.
Desigo CC does not use PTP.
Internetwork
Network