If you want to read data from a specific SCADA Server, you can access it by using its physical node name. The SCADA Server can be active or standby, but a session must be established to it. Data is not available on the iClient if communication with that SCADA Server is lost. You can read or write data to the active SCADA node. You can read data from the standby SCADA node but you cannot write data to it.
iFIX pictures, with links using a logical node name, always attempt to show data from the active SCADA regardless of whether it is the primary or secondary SCADA. This is done without requiring the picture to be opened, closed, or replaced.
When an iClient establishes a connection to an active SCADA Server node, it starts to read data from that node. If the active SCADA Server node becomes unavailable, the iClient loses its session with that node, and causes a message box to appear with following message:
Node.Tag.Field Connection Not Established With Node
To disable this message, you can edit the FilteredErrors.ini file, which is located in the C:\Program Files (x86)\Proficy\iFIX\Local directory, to include error number 1914. Once you have edited this file, you must restart the iFIX WorkSpace for the change to take effect.
When the iClient switches to a newly active SCADA node, the following events occur:
- The standby node becomes the active node, and the active node becomes the standby node.
- The links in the open pictures on the iClient display @ symbols (as the default) to indicate that the session with the previously active node has been temporarily lost.
- The pictures resolve automatically using the information from the newly active node. This ensures data integrity.
- The @ signs are replaced with process data from the newly active node. The node name referenced by these links does not change; it continues to display the name of the logical node.
- An event message indicating that a failover has occurred is sent to all alarm destinations configured for the iClient when failover occurs.
NOTES:
- You can change the default @ signs using the Comm Error setting on the Animations Data Error Defaults tab in the User Preferences dialog box of the iFIX WorkSpace.
- The physical and logical names of a SCADA server are set in the SCU in the Local Startup Definition. The physical node name is set using the LocalNodeName field. The logical node name is set using the LocalLogicalName field.
