High Availability

The High Availability symbol that ensures continuous access to PI Vision by automatically triggering a reload in the event of a connection loss or timeout. This symbol serves as a failover mechanism, helping maintain uninterrupted access to critical data visualization. It constantly monitors the connection status and responds by initiating a reload process whenever a loss of connectivity is detected. This feature guarantees that users experience minimal disruption and can continue interacting with PI Vision once the connection is reestablished.

Starting the Control

To start the control click on the “Assets” button in the upper left corner of the PI Vision display.

In the upper part select “weruHighAvailability” by clicking on it.

Afterwards an arbitrary attribute from the asset tree could be added to the display via drag and drop. The HA control appears on the display and can be used.

Configuration

With a right click on the control it is possible to press "Configure". Thereby the configuration tile appears.

The "Enabled" option switches the control on or off. (Before editing the options, it is always best to switch the control off first to prevent incorrect server queries).

When Server watching is enabled:

The "Server 1" option specifies the first server to be controlled. (This field is required)

The "Server 2" option is optional and specifies the second server to be controlled.

The "Interval(ms)" option specifies the time interval in milliseconds in which the server(s) will be checked.

The "Max Timeout(s)" option specifies the maximum time in seconds a server can take to be counted as unreachable.

When PI watching is enabled:

The “PI Server“ option specifies the PI Server from witch the PI tag gets periodically read.

The “PI Tag“ option specifies the PI Tag that is periodically read from the PI Server.
Note: This PI Tag needs to change its value at least once every Data update (every 5 seconds) to use PI watching.

The “Max skipped PI updates“ option specifies how many PI updates can be skipped until the PI System is considered unresponsive.

The “Warn Offset“ option specifies how many skipped PI updates before a Page reload this control should start warning you.

The “Max Timeout“ option specifies how long in seconds no PI Update can occur until the PI System is considered unresponsive.

When Static Refreshing is enabled:

The “Intervall“ option specifies in wich frequency in seconds should the Display be reloaded.

Functionality of the Control

Functionality depends what Methods are enabled (multiple Methods can be activated at the same time).

When Server Watchdog is enabled:

If only one server is stored:

Server 1 is queried periodically to see if it can still be reached.

If the connection fails, the page is reloaded. So that your server redundancy is used.

(This option should only be used if you have more than 1 server running over one URL).

If two servers are stored:

Server 1 and server 2 are periodically queried whether they are still accessible.

It is automatically switched to the other server in case of failures, if necessary.

When PI Watchdog is enabled:

Two things happen every Data update:

Normal PI Updates will be checked for integrity
The PI Tag is read from the PI Server to check if data can be read and if data can still change on the PI side (The used PI Tag should be a value that is changing every 5 seconds)

If the specified amount of PI Updates gets skipped the Display will be reloaded.
The Display will also be reloaded when the specified amounts of seconds passed without a single update.

This is why this Method should only be used when using a real time Data Display. (only then there are periodical data updates)

When using Static Refreshing:

The Display will be reloaded periodically in a specified amount of time.

Default Configuration

The configuration file "weruPIVisionSuiteConfig.js" is located on the PI Vision Server within /PIVision/Scripts/app/editor/symbols/ext/libraries and contains the default configuration of the PI Vision Suite.

In the "HAconfig" section, the default configuration for the High Availability Control can be set. These values are adopted as the configuration when the control is dragged into the display and can be changed later by right-clicking → Configure.

This can only be changed by an admin!

Removing the Control

Before removing the control it is necessary to switch into edit mode (Icon in the upper right corner). Thereafter it is possible to click on the control and press the delete key to remove the control.