dsc OPC client instance timing

[ebnelson]

I am using DSC to interface to an OPC server running in my facitity.  The OPC server refreshes it's tags over a wireless connection to a remote location.  I need to control how often the OPC server refreshes it's tags /bc the bandwidth can be completely consumed if the number of tags is large.  To get this OPC server data into my Labview app I use the OPC client instance from the DSC module.

I have found the update rate setting on the OPC client but I'm not sure what this setting actually does.  If I place my shared variables (bound to the OPC client) into a while loop running with little or no delay the bandwidth is consumed very easily. 

My question is, can I limit the update rate of the OPC client or is the update speed tied to how often I ask for data?  It would be very convienient to me if the OPC client would return the last updated value for the time between "scheduled" reads.  Does this ring a bell to anyone out there?

eric

[CKap]

Hello Eric,

I would recommend that you refer to the help file for detailed information on the update rate for an OPC I/O Server. You can get to this specific section by clicking on the Help button while configuring an OPC IO server or by searching for "Configure OPC Client" in LabVIEW help.

As far as your last question is concerned, whenever a shared variable is read then its value is provided by the shared variable engine. If the original value has not been updated by the OPC server then the shared variable engine would return the locally cached value. Since the shared variable engine is acting as a client in this case, the onus lies on the OPC server to manage the tag update rates.

Hope this helps,

Chetan K

Application Engineer