Common global data is a new and improved process for data synchronization across like devices (used instead of Data replication) incorporating a global data server and client devices. The global data server/client devices must be on the same ALN (defined by the ALN name property). Each ALN supports one global data server and a maximum of 64 global data client devices.

  • A global data server is a device that provides synchronization updates to global data client devices. Changes on the server are synced to client devices on the same ALN.
  • A global data client is a device configured to receive updates from the global data server.

A global data server is defined in the Device object. Global data client devices must be added to the server's Node table by using the Node table editor in the web interface. For details, see the PXC.A Web Interface User Guide, (A6V12893115).

In each ALN network, one controller is designated as the Global Data Server. All other ALN controllers are global data clients. Global data is writable over the network in global data servers and read-only in global data clients. Global data servers manage global data change counts.


Synchronization of data can take up to 5 minutes. If the global data server goes offline, last known data is used by the global data client devices until the server comes back online.

During normal network management ePing sequence, a global data client receives an updated global change count from the server in the ePing response.

  • If the global change count received from the server differs from the client's, the client’s data image is out of date and is responsible for scanning the server's change count to update its global data image. Global data will also resynchronize if the client is reloaded by the tool.
  • If the global change count received from the server is equal to the client's, no synchronization action will occur.