I have to connect to OPC DA server from LabVIEW and read more than 400 tags synchronously/asynchronously. I know there is an option with NI DSC module to create LabVIEW OPC client.The problem is I do not want to buy NI DSC license because it has overhead functionality and hence costs a lot.
I am curios if you had an experience to connect OPC DA server without NI DSC from LabVIEW.
Leon PetrovLeon Petrov
2 Answers
In addition to Yair's answer I have found an very useful toolkit here for $295 that provides fast and simple mechanism to connect to OPC servers from LabVIEW. I have tested with trial mode and it seems my problems are solved with this. http://opc-da.com/
Connection in identifies the data source to read.connection in can be a string that describes the URL, a shared variable control, a connection id reference parameter output from a DataSocket Open function, or a connection out parameter output from a DataSocket Write function.: type (Variant) specifies the type of data you want to read and defines the type of the data output terminal. For example, the URL opc:/National Instruments.OPCDemo/sine, sine is the ItemName, which is passed by the ItemID and AccessPath, but when using the datasocket to connect with OPC server, there is no way to give an AccessPath different from the ItemID. When the data is returned and communicated by datasocket, LabVIEW uses VariantChangeType to.
Leon PetrovLeon Petrov
The DataSocket Read primitive supports OPC, but my understanding was that it doesn't really work well with a large number of tags. My own experience with it was with a relatively low number of tags and years ago, so you will have to test for yourself, but it should be built into LV, so it satisfies the cost requirement. You could possibly also control the way you read the tags to work around any performance issues it might have.
Note that you will probably need to add DS support to any installer you build.
YairYair
![Labview Datasocket Example Labview Datasocket Example](http://docplayer.net/docs-images/27/12216373/images/21-0.png)