Failover settings
- Last UpdatedMay 22, 2025
- 3 minute read
UniInt-Interface Level Failover
The following three options are enabled only if warm failover is enabled on the UniInt > Failover page:
-
Warm_1: Do not create groups on the server (/fm=1)
-
Warm_2: Create inactive groups and add PI points (/fm=2)
-
Warm_3: Create active groups; do not advise groups (default) (/fm=3)
Note: For more information on UniInt-Interface level failover modes see UniInt failover modes.
-
Percent of tags accepted by OPC Server as valid
Specify the percentage of points that are required to be accepted by the OPC server as valid. If less than this percentage is accepted, PI Interface for OPC DA sets its device status to Connected/No Data, which triggers failover if UniInt failover is configured. (/rp).
-
Maximum number of Watchdog Tags which can have Bad Quality or Any Error without triggering Failover
Specify the maximum number of watchdog PI points that can have an error or bad quality before failover is triggered. You can configure watchdog PI points to control failover when the interface is unable to read some or all of the items, or when the items have bad quality. This feature enables you to trigger failover when a data source loses the connection to one OPC server, but is able to serve data to the other. To configure watchdog PI points, set location3. For a watchdog point that is in an advise group, set location3 to 4. For a watchdog point that is in a polled group, set location3 to 3. (/uwq).
Cluster Interface Failover
To make selections in this option, first enable it by selecting the Enable Cluster Interface Failover check box. Note this tab is only available when UniInt Failover is not selected.
|
Setting |
Description |
|---|---|
|
This node is the |
Specify whether this node is primary (/pr=1) or backup (/pr=2). |
|
Failover Mode |
Warm_1: Do not create groups on the server (/fm=1). Warm_2l: Create inactive groups, and add points (/fm=2). Warm_3: Create active groups, do not advise groups (default) (/fm=3). |
|
Cluster Mode |
Configure behavior of the backup interface. Primary Bias: This node is the preferred primary. (/cm=0). No Bias: No node is preferred. The active PI OPC interface stays active until the cluster resource fails over, either as the result of a failure or through human intervention. (/cm=1). |
|
Resource Number for APIOnline |
Identify the apionline instance that goes with this interface instance. For example, to configure the interface to depend on an instance named apionline2, set this field to 2. To configure the interface to depend on an instance named apionline (no resource number), set this field to -1. (/rn=#). |
|
Active Interface Node Tag |
Specify the string point that contains the name of the currently active OPC interface node. (/cn). |
|
Health Tag ID |
This parameter is used to filter UniInt health points by location3. The parameter must be unique for each interface – failover member parameter. If this parameter has an invalid value or is not set, the default value of 0 is used for the location3 attribute when creating UniInt health points. (/uht_id). |
Server Level Failover
|
Setting |
Description |
|---|---|
|
Backup OPC Server Node Name |
The name or IP address of the backup OPC server node (/backup). |
|
Backup OPC Server Name |
The registered name of the backup OPC server (/backup). |
|
Number of Interfaces on this Node |
The number of instances of the interface that are running on this node (/ni=#). |
|
Switch to Backup Delay (sec) |
The number of seconds to try to connect before switching to the backup server (/ft=#). |
|
Wait for RUNNING State (sec) |
The number of seconds to wait for RUNNING state before switching to the backup server (/sw=#). |
|
Current Active Server Tag |
(Optional) String PI point that contains the name of the currently active server. If set, the interface writes the name of the OPC server to this point whenever it connects. Useful for debugging server-level failover. (/cs=tag). |
|
Primary Server Watchdog Tag |
Watchdog point for the primary server (/wd1=tag). |
|
Backup Server Watchdog Tag |
Watchdog point for the backup server (/wd2=tag). |
|
Multiple Watchdog Tag Trigger Sum |
The minimum total value of the watchdog points. Failover is triggered if the sum of the value of these points drops below the specified value. (/wd=#). |
|
Maximum number of Watchdog Tags which can have Bad Quality or Any Error without triggering Failover |
Default=0 if only one watchdog point. Cannot exceed the number of watchdog points defined. (/wq=#). |
|
Failover if Server Leaves RUNNING State |
Triggers failover if the server state changes to anything other than RUNNING.(/ws=1). |