User Manual

Network architecture
BACnet architecture (MLN & ALN)
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Range/Value Description
0 Reserved for applications with only one BACnet network in a BACnet internetwork, that is, where
there are no BACnet routers.
1...65280 Network number for stationary BACnet networks. You can select any network number in this range.
We recommend that you form categories, e.g.:
BACnet/LonTalk networks via (half)router: 1...99
BACnet/IP network (common network): 100
Desigo CC or XWP/ABT connected via BACnet/PTP
:
1000...1099
65281...65534 Reserved for temporary BACnet networks. Not yet used in Desigo.
Router parameters
The router parameters are written to the BACnet router during commissioning. The following information is
required for each port (logical connection to network):
Designation Description
Network Number Network number of the directly connected network.
Max NPDU Length Max. message length supported in this network. This value depends on the transport
medium used.
Values for LonTalk: Range: 50/228
Default: 228
Values for MS/TP: Range: 50/228/501
Default: 501
Value for IP (equal for IPv6): Range: 50/228/501/1497
Default: 1497
Values for PTP: Range: 50/228/501
Default: 228 for LonTalk
/ 501 for Ethernet/IP
Hop counter
Every BACnet that is routed to another BACnet network has a hop counter. The counter reading is reduced
by one with each pass of the BACnet router. When the counter reads 0, the message will not be routed
further. This prevents continuously circulating messages.
Definitions for Desigo
For Desigo the hop counter is initialized with a fixed value of 5. This means that a message can pass
through a maximum of four BACnet routers.
LonTalk data link layer
The LonTalk data link layer is supported by the PX automation station and by the operator units and tools.
LonTalk ist he communications protocol for LonWorks technology.
Addressing under LonWorks technology
Physical address, neuron ID : The Neuron ID is the physical address for a LonWorks device. It is a unique
48-bit (6 byte) identifier which is assigned to each neuron chip during manufacturing.
Logical address : The logical LonTalk address is written to the LonWorks node during commissioning on the
network side.
Application Layer
Network Layer
PTPIPLonTalk MSTP