User Manual

System overview
Communication principles
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The primary server carries out system functions, such as time synchronization,
life check and the distribution of global data:
● Time synchronization: The primary server distributes the current time to the
backup devices.
● Life check: The backup servers detect the failure of the primary server and
the primary server detects the failure of the backup servers. If a server fails,
an alarm message is sent. If the primary server fails, another automation
station must be defined manually as the primary server.
● Distribution of global data: Global objects are available on all PX
automation stations. The primary server synchronizes changes, e.g.,
calendar object, notification class object, that are made on the primary
server to the backup servers.
Handling a PX Site in Desigo clients
When an operating device starts, it searches for all primary servers and offers a
log in to the PX site.
A Desigo CC site can contain several PX sites and third-party devices. Desigo
CC registers itself as a global alarm recipient for the PX site on the primary
server.
3.8 Communication principles
Desigo uses open communications to connect various technical building
systems based on open and standardized data interfaces:
● BACnet is used from room automation to the management level
● KNX®, DALI, EnOcean® and LonWorks® are used in room automation and
decentralized secondary processes
● M-bus, Modbus, OPC, MS/TP, and other interfaces are used for connecting
third-party devices and systems
BACnet
BACnet (Building Automation and Control Networks) is a communications
protocol for building automation and control networks. BACnet ensures the
interoperability between devices from different manufacturers.
See http://en.wikipedia.org/wiki/BACnet.
VendorID
Each BACnet device has a VendorID to identify the manufacturer. The VendorID
for the Siemens BACnet system devices is 7.
BACnet over Ethernet/IP
Applications on the management level can interact via standard IT network
services concurrently to BACnet services.
Desigo supports BACnet/IPv4 and BACnet/IPv6 (via PXG3.M/L router). IPv6 to
IPv4 is NOT compatible. The parallel operation of IPv4 and IPv6 is possible with
the use of a PXG3.L/M BACnet router.
See http://de.wikipedia.org/wiki/IPv6.
Network performance
The performance of the network depends on the following criteria:
● Number of devices on the bus
● Segmentation of the topology via routers (for LonTalk bus)
● Number of simultaneously active clients
● Peer-to-peer communication resulting from distributed PX applications