dpConnect

[mhargreaves]

When I do a dpConnect from an API manager, I get all connected datapoints returned when any one of them changes.

Is there a way to request to be notified of the ones that change only?

(I am doing a developer course in a few weeks time so may learn it there, but am trying things out in the meantime!)

[mkoller]

When you do a dpConnect() with a list of DPs, then this is normal. You subscribe for all of them together as a group. When one of them change, you get the status of the whole group.
When you just want separated values, do multiple dpConnects

[leoknipp]

Hello,

I'm not an API specialist.
In CTRL you can use dpQueryConnectSingle() if you want to get only those elements which are changed for a list of connected dp elements.
Maybe you can use this function also in the WinCC OA API.

Best Regards
Leopold Knipp
Senior Support Specialist

[mhargreaves]

What query should I use to be notified if a datapoint of a given type is added or deleted?

[leoknipp]

Hello,

is your question related to CTRL or API?
When using an API manager you get a specific message when a datapoint is created or deleted. There is no possibility to start a query where you get the information when a datapoint is deleted.

Best Regards
Leopold Knipp
Senior Support Specialist

[mhargreaves]

Hi Leopold. Thanks.

Yes, I was talking about the API.

I will look into how to do this using the API.