I am interesting in learning all I can about OPC and vb.net. Does the net framework provide any classes for building OPC clients? I have visited plenty of sites and there are a lot of tools to choose from. I am having a hard time deciding which ones are the best. So far I have visited the OPC Foundation which requires a 600 dollar membership fee. Matrikon, which has plenty of tools, but they dont provide support for costum developing. The best one I have found so far is Metadynamics, they have provide me with a handy dll file that contains all the com and wrappers to read, write to opc servers, the problem with them is they cost 200 dollars for every machine; that I wish to install an app on, that can get spendy. Mainly I am just looking for some experienced developers who have used OPC before and know what the best tools are for developing custom apps in vb.net.