Client/Designer Module - OPC access

Hi !

I’m trying to get data from OPC-tree in the Client or the Designer. But I can found no examples of this.
How can I subscribe to a value from an OPC-path I have ?
How can I browse to find which noses are availables ?

Thanks for your advices !

Benoit.

Not entirely sure I understand your question, but generally only the gateway will subscribe to OPC items, by creating an OPC SQLtag. Then your client binds that tag into your display. There are scripting functions that allow a client to bypass the tag system and browse, read, or write to OPC directly, but not to subscribe.

Thanks for replying !

My Gateway Module creates and updates an OPC-tree.
I want my Client/Designer module to display theses values. I thought the better was to subscribe to the the OPC-tree values. But if subscribtion is not possible, reading will be fine. I did not find an example of a module that uses the OPC tree, even the Weather Module populates an OPC tree but did not uses it afterwards.

How to do to read the OPC tree from the Client ?

[quote=“benoit”]My Gateway Module creates and updates an OPC-tree.
I want my Client/Designer module to display theses values. I thought the better was to subscribe to the the OPC-tree values. But if subscribtion is not possible, reading will be fine.[/quote]Subscription is better. That is why SQLtags subscribe to OPC items. Clients then subscribe to SQLtags (via binding) as needed for display. Multiple clients share data subscribed via SQLtag, which is a primary reason SQLtags exist.[quote=“benoit”]I did not find an example of a module that uses the OPC tree, even the Weather Module populates an OPC tree but did not uses it afterwards.[/quote]That’s because users of OPC data inside Ignition are expected to make SQLtags of the OPC items needed and display those.[quote=“benoit”]How to do to read the OPC tree from the Client ?[/quote]Look at the system.opc.* scripting functions.