This ObjectType is a subtype of NonTransparentRedundancyType intended to be used to identify the capabilities of the Servers which support non-transparent primary with backup redundancy. It is formally defined in Table 23.

A Server represented by this Type shall use the Warm Failover mode defined in OPC 10000-4.

Table 23 – NonTransparentBackupRedundancyType definition

Attribute	Value
BrowseName	NonTransparentBackupRedundancyType
IsAbstract	False
References	NodeClass	BrowseName	DataType	TypeDefinition	Modelling Rule
Subtype of the NonTransparentRedundancyType defined in 6.3.9.
HasProperty	Variable	RedundantServerArray	RedundantServerDataType[]	PropertyType	Mandatory
HasProperty	Variable	Mode	RedundantServerMode	PropertyType	Mandatory
HasComponent	Method	Failover	The method has no parameters.		Mandatory
Conformance Units
Redundancy Server

The Mode Property represents the current operating mode of a Server in a non-transparent redundant server set. It is an enumeration defined in 12.44. This Property is used to indicate the availability status of backup Servers. A Server operating in primary mode provides the availability status of backup Servers and a Server operating in backup mode provides its ability to take over the primary operating mode. A Server operating in BACKUP_READY, BACKUP_NOT_READY or PRIMARY_ONLY mode shall use a ServiceLevel in the degraded range. A Server shall use a higher ServiceLevel value for BACKUP_READY than BACKUP_NOT_READY.

The Failover Method is used to request a manual transfer of primary and backup modes. This method has no arguments. This Method call may be directed to a primary or a backup Server. When called on the primary and more than one backup is ready to take over the primary will use some vendor specific logic to determine which backup will assume the primary mode. When called on a backup which is ready to take over, it will become the primary. The Server should set the Executable Attribute of this method to indicate if the failover is currently possible.

Signature

Failover(

);

Method Result Codes (defined in Call Service)

Result Code	Description
Bad_InvalidState	Defined in OPC 10000-4 This is returned when the failover failed due to the current RedundantServerMode mode of a primary being PRIMARY_ONLY or a backup being BACKUP_NOT_READY.
Bad_UserAccessDenied	Defined in OPC 10000-4