Understand InTouch remote reference limits

There are two types of InTouch remote reference tags. A static remote reference is hard coded to a fixed remote address when you define the tag from the Tagname Dictionary. A static remote reference is assigned a tag handle in the tag database when the application starts running. A static remote reference tag count sticks while the application is running.

A dynamic remote reference resolves the target address while the application is running. If the dynamic remote reference tag is assigned a database handle, the target address can be changed during run time by using the .Reference dotfield or IOSetRemoteReference() function within a script.

The following figure shows an example of an InTouch application running under a 300K license without sticky remote reference tags. The count for the static remote reference tag sticks while the application is running. But, the count for the dynamic remote reference tag is only for the active tag source. The previous connections to remote tag sources do not stick and are not counted in the remote reference or total tag count.

The InTouch 60K license does not use sticky tag counts that impose limits on the number of dynamic remote tag references. This allows an application to dynamically access more than 60K tags during the period the application is running. The tag use count for dynamic remote references fluctuates up and down as windows with remote references are opened and closed. But, the application can never have more simultaneously active tags than the implementation limit of the run-time tag database.

Dynamic reference tag counts only fluctuate up and down when WindowViewer uses disk storage to save the contents of a running application. If WindowViewer is configured to cache InTouch windows or Industrial graphics, the remote reference tag counts may not decrease unless a window is removed from the cache.

When a window is not visible does not mean the remote tag references are not still bound to their sources. However, if window caching is completely disabled, and no high priority windows have been specified, then WindowViewer operates much like the legacy "Always load from disk" scenario. In this case, all windows are removed from memory when they are closed and the dynamic remote tag references are reclaimed in a 60K license environment.

A remote reference from an I/O tag is not included in the sticky remote reference count of the InTouch license. An I/O tag’s remote reference can change an unlimited number of times without counting against the sticky remote reference limit.

When fail-over to the secondary tag source occurs, the application can access the same items from the secondary source without increasing the licensed tag count. After failover, accessing new items from the secondary tag source increases the tag count. These items are accessible after fail-back to the primary tag source.

After the tag count reaches the licensed maximum, no further items can be activated regardless of whether they are accessed from the primary or secondary tag source.