WebIQ groups items with the same subscription interval into a single subscription to the OPC-UA server. You have to define the subscription interval per item: https://www.smart-hmi.com/user/download/deliver/docs/documentation-manual-webiq-designer-2.15-ee64/index.html#_source_area Your second question is not quite complete as you have to consider that the same HMI can be open in multiple devices at once. WebIQ behaves very smart with this: - an item is only subscribed with the OPC-UA server when it is currently subscribed by at least one widget/LocalScript in the HMI - an item will be unsubscribed when the widget is no longer used, i.e. on a different view of a screen for example - this is valid for all HMIs display open at once, i.e. if a single HMI display has a specific item subscribed it will be subscribed with the OPC-UA server - however, if multiple HMI displays use that item there will only be once single subscription to the OPC-UA server In general, WebIQ uses the most efficient OPC-UA subscription model: only subscribe items when they are actually used in at least one HMI display currently. Please note that however - when it comes to the maximum number of item subscriptions - you have to take into the account the maximum number of concurrent displays of the HMI you expect because one HMI display can be on screen 1, another on screen 2 and another on screen 3 - if now all of these screens have 10 different items you have 30 item subscription. If all screens have the same 10 items you only have 10 item subscription.
... View more