Components of Enhanced Failover

Enhanced Failover is the capability to switch over automatically to a standby SCADA Server when a failure occurs. The switchover from the active to the standby SCADA Server occurs without user interaction, unless it is manually triggered. There are certain components that need to be configured and running to allow this switchover to occur.

The following components are included in the iFIX Enhanced Failover configuration:

The running components of iFIX Enhanced Failover system also include:

Active SCADA

The Active SCADA scans its database, communicates with the PLCs, and generates alarms. Periodically, it sends its database to the standby SCADA over the dedicated SCADA Synchronization network.

Standby SCADA

The Standby SCADA is ready to take the place of the Active node if the need arises. SAC does not poll the database or generate alarms on this node. Instead, the Standby SCADA receives database and alarm information from the Active node.

Logical SCADA Name

A logical node is a pair of SCADA nodes configured for use with Enhanced Failover. A logical pair consists of a Primary and a Secondary node. A client uses the logical node name to obtain data from the Active SCADA node in the pair, and to communicate with the Active SCADA node. Each Enhanced Failover SCADA node (both Primary and Secondary) is defined by a unique physical name and a common logical name.

The SCADA pair consists of a Primary node which is the preferred node in the pair, and a Secondary node which is the backup node in the pair, each having a role/status.  When Enhanced Failover is enabled, one node will be Active, and the other node will be in Standby. The Active node functions as a normal SCADA node. SAC is processing the database and alarms are being generated on the Active node. Additionally, the Active SCADA node periodically sends database and alarm information to its partner, the Standby node.

iClient Connections

iClient nodes allow operators to obtain data and alarms from the Active SCADA node. Clients must be connected to the SCADA in “Active” mode to change data, acknowledge alarms, or write data to the PLC.

It is required that you have a dedicated network connection for SCADA synchronization and a separate connection for iFIX Client connections. iFIX Clients follow the Active SCADA. When a failover occurs, the Clients are notified to connect to the new active SCADA. For more information on configuring iClients, refer to the Configuring iClients sections.

SCADASync.exe

SCADASync.exe is the process name of the iFIX application that performs the synchronization.

For more information on this process, refer to the What is Enhanced Failover? and What Happens when a Failover Occurs? sections.

SCADARoleMgr.exe

SCADARoleMgr.exe is a process that decides if the SCADA node will be active or standby.

For more information on this process, refer to the What is Enhanced Failover? and What Happens when a Failover Occurs? sections.

SCADASyncMonitor.exe

The SCADA Sync Monitor (SCADASyncMonitor.exe) displays information about the primary and secondary SCADA Servers. You can use it for viewing diagnostic information about your Enhanced Failover configuration, or for troubleshooting issues with your Enhanced Failover configuration. For more information on this application, refer to the Enhanced Failover Diagnostics with the SCADA Sync Monitor section.

iFIXNotificationFG.exe and iFIXNotificationBG.exe

iFIX Notification (iFIXNotificationFG.exe and iFIXNotificationBG.exe) notifies a user on a Client that it is only able to communicate with a standby SCADA node. You cannot write to a standby SCADA node, and a standby SCADA node does not generate any alarms. Since this limits what the operator can do, a modal message box appears informing the user about the condition until the active node becomes available again. For more information, refer to the iFIXNotification.exe and Enhanced Failover section.

SCADASync.log and ScadaRoleMgr.log Files

For Enhanced Failover, there are two additional log files available for troubleshooting. The SCADASync.log includes messages that occur during the SCADA synchronization process. The ScadaRoleMgr.log includes messages that occur during the active to standby node switchover. For more information on these log files, refer to the Log Files for Enhanced Failover section.

Network Status Display (NSD) Tag

The Network Status Display tag is a special tag residing on each networked node that displays diagnostic, failover, and network information. Networking in the SCU must be enabled to view this tag, which can be added to your custom iFIX pictures. This tag also provides fields for manually triggering failovers: A_SWITCHSCADAROLE and F_SWITCHSCADAROLE.  For more information, refer to the Network Status Display Fields section.

Enhanced Failover Runtime Information (SCADASync) Tags

The SCADASync tags are special tags consisting of runtime information for your Enhanced Failover configuration. Enhanced Failover must be enabled in the SCU to view these tags. The SCADASync tags are very helpful for troubleshooting your Enhanced Failover configuration, and can be added to your custom iFIX pictures. Many of these fields can be viewed from within the SCADA Sync Monitor; however, there are more SCADASync fields than what is displayed in the SCADA Sync Monitor. Use these tags to obtain additional information, for instance, regarding your data synchronization transports. For more information on these tags, refer to the Runtime Information Fields for Enhanced Failover section.