You can create 32-bit or 64-bit, or platform-independent applications with OPC Data Client. 32-bit applications can also run on 64-bit systems. 64-bit applications can only run on 64-bit systems. Normally, you will target your application to “Any CPU”, and the same code will then run on both x86 and x64 platforms.
Supported platforms are x86 (i.e. 32-bit), and x64 (i.e. 64-bit). The product has not been tested and is not supported on the Itanium platform (IA-64).
When you use OPC Data Client for COM development, the components are compiled using the “just-in-time” by the .NET runtime for either 32-bit or 64-bit execution, depending on the bitness of the process that loads the OPC Data Client components.