Terms You Should Know When Working with Enhanced Failover and LAN Redundancy

Before you begin working with Enhanced Failover in iFIX you should familiarize yourself with the following terms:

Term

Description

Enhanced Failover

The process of switching the active SCADA node from a waiting, standby SCADA node, when the active SCADA node becomes unavailable for processing data.

Active SCADA

The fully functioning SCADA node in run mode. The active node sends the process database to standby node. All iClients retrieve their data and alarms from the active SCADA. The active SCADA generates alarms.

Standby SCADA

The “Idle” SCADA·node in run mode. Updates to the standby SCADA are based on database synchronization updates pushed from the active node. The standby node replaces the concept of the backup node in previous versions of iFIX, prior to iFIX 5.0.

Physical Node

The physical node (also called the local node) is the local iFIX node name, and should be unique within your iFIX network.

Logical Node

A logical node is a pair of SCADA nodes configured to use Enhanced Failover. A client using a logical node obtains data from the active SCADA node in the pair.

Primary SCADA

The first node that you configure in your primary and secondary pair in configure mode. This is the node that goes active when you start iFIX, but may not always be the active node.

Secondary SCADA

The second node that you configure in your primary and secondary pair.

Synchronization

A process that occurs on the active SCADA node, where the iFIX process database and all files in the PDB folder changed from the last update are copied to the standby node.

The actual process name of the iFIX application that performs the database synchronization is SCADASync.exe. The ScadaRoleMgr.exe works in tandem with the SCADASync.exe, and assigns the roles during failover.

iFIX Client node

Operators view process data received from a SCADA Server using a client (SCADA or iClient node).

The client obtains data and alarms from the active SCADA node:

  • A client automatically switches over to the newly active SCADA when a failover occurs.
  • Any VBA script on the client continues to execute when a failover occurs. If the VBA script is reading data while the failover occurs, the VBA script may return an error.
  • The Alarm Summary shows the same number of alarm and acknowledge states after a failover occurs. The real-time trend shows some gap in the line chart.