Setting up more than two I/O Servers per cluster

If you need to add more than two I/O servers to a cluster, you need to define a redundant I/O device called NetworkTagsDev for each of the servers. If you do not do this, you can lose device status information during runtime.

If the cluster includes only one or two I/O Servers, the I/O devices are automatically added when you add the cluster during I/O Device Manager configuration (see Plant SCADA Help for details). If a system has more than two I/O Servers in a cluster, you must manually add the NetworkTagsDev I/O device for the remaining servers (after the first pair).

To create the board, port, and NetworkTagsDev I/O device, ensure the following:

  • All redundant NetworkTagsDev I/O devices have the same number
  • The Startup Mode field is set to Standby; do this for all standby NetworkTagsDev I/O devices, including the one created by the I/O Device Manager
  • The Equipment field is set to <Cluster>_NetworkTagsDev

The field values for the forms in each of the I/O servers should be:

Boards Form
Board Name: <any unique name> (suggestion: BOARDy_SVRz)
Board Type: IEC61850N
Address: 0
Leave everything else blank.

Ports Form
Port Name: <any unique name> (example: Px_BOARDx_PRJz)
Port Number: <any unique number within the I/O server> (suggestion: x)
Board Name: <use the board name defined previous>
Leave everything else blank.

I/O Devices Form
Name: NetworkTagsDev
Number: <same number as the one defined in the corresponding device>
Address: NetworkTagsDev
Protocol: IEC61850N
Port Name: <use the port name defined previous>
Startup Mode: Standby
Equipment: <Cluster> _NetworkTagsDev
Leave everything else blank.

NOTES:

  • Startup Mode is only visible when in extended form mode (press F2 to toggle between simple form mode and extended form mode, while in the I/O device form).
  • The Equipment field is hidden by default. To change it to visible, open units.dbf (in the project folder) in Excel.
  • If the system has one or two I/O servers per cluster, the startup mode of the standby NetworkTagsDev I/O device could be set to StandbyWrite in the I/O Device Manager. If the system has more than two I/O servers per cluster, the startup mode of all standby NetworkTagsDev I/O devices must be set to Standby.
  • One side effect of this is that, when the system switches to a redundant I/O server, affected devices will momentarily lose communication as the system transitions to the redundant server.
  • If the primary and redundant alarms servers are synchronizing, data will be slow to display in the Alarm Log and Events Log.