The role of the primary server

Server/Function

Function and description

Primary server (Desigo PX)

One automation station of a site acts as the primary server. Make sure that only one primary server exists at any one time on a site.

Life check

The primary server monitors the backup servers and the third-party BACnet devices of a site.

The primary server can monitor the Desigo room automation server.

Time synchronization

The primary server synchronizes the time of the backup servers and the third-party BACnet devices of the site.

The primary server can synchronize the Desigo room automation server time.

Start-up

No coordinated start-up.

Replication

The primary server replicates the global objects and properties (device object) to the backup servers of a site. A backup server accepts changes of global objects only from the primary server.

The role of the backup server

Server/Function

Function and description

Backup server (Desigo PX)

The other automation stations of a site must be backup servers.

Life check

The backup servers monitor the primary server of the site.

Backup servers can monitor Desigo room automation servers.

Time synchronization

The backup server can synchronize the time of the Desigo room automation server and of the third-party BACnet devices.

Start-up

No coordinated start-up.

The role of the Desigo room automation server and third-party BACnet device

Server/Function

Function and description

Desigo room automation server / Third-party BACnet device

The Desigo room automation server acts like a standard BACnet device.

Life check

The Desigo room automation server / third-party BACnet device is monitored by the primary server or the backup server.

Start-up

No coordinated start-up.

Replication

No global objects to be replicated.

The role of the clients

Server/Function

Function and description

Clients

A client can read global objects from the primary server or any backup server. A client may only modify a global object (e.g., with WriteProperty) on the primary server. Each client must therefore recognize the primary server of a site. A client can query the identification of the primary server of a site.

Replicated objects from backup servers which are not online or which are connected to the BACnet network at a later stage, are updated by the primary server as soon as the primary server becomes aware of them. This occurs after a restart of the automation station, after connecting it to the network or on expiry of the synchronization request period [SynReqp].

The role of the alternative primary server

Server/Function

Function and description

Alternative primary server

If the primary server fails, no global objects can be modified. You can configure any backup server of the site to act as the primary server using a client or Xworks Plus (XWP).