Labview datasocket & OPC servers


Thread Starter

Richard Bland

Using Kepware Kepserver, siemens S7 plc and Labview 6i. Lots of slowdown when using multiple datasocket writes in same while loop.

Has anyone had any experience of using the above equipment to get a sensible write time to the OPC server. If I just use one datasocket write VI in a while loop I get a sensible update time to the PLC. If I add a second, I start to get update times of 2-3 seconds, and if I add a third, update time can exceed 5 seconds. The Kepware quick client has no problems updating at 100ms intervals, but it seems Labview is not communicating the data to the OPC server and this is where the delay is. Does anyone have any thoughts or experience?

Richard Bland

Zan Von Flue

I have alittle experience with scada's and plc's (S7!). The major item to watchout for is that the information you want to read or write from the PLC should be sequencial. I mean read the information i.e.
DB20.DBD0 to DB20.DBD100.
This is the quickest way to get information, in a block.
If you request information :
DB20.dbd20, then DB5.DBD3 ... etc.
every piece of information request is individually send and takes longer. I would also limit the information. This has to be set up in the Scada node. If you find that the information refresh is to slow seperate the refresh times between important information (quick refresh) and not important information.


Having been in your position already, I have used OPCWare Client Developer succeffully in Labview. It's an ActiveX control that plugs straight into Labview and handles complex OPC configurations with speed, without using datasockets. You can find it at