Many of the large scale SCADA applications are run in Windows NT technology these days. In NT family, applications are run in isolated spaces, and this avoids one application 'hanging' and causing non-transfer of sliced-time to other applications. It is quite common for many of the realtime systems to transfer data in realtime to an excel file, so that small files can be taken out as analysis sample. Apps are mostly written in vc++, and at times, in VB. One of the best tools in Telecom develpment available now is VBVoice. These tools allow you to route and manage high-traffic communication channels using VB. (It also supports .NET, VC++ etc). Using low-level calls, there is no limitation to what a programmer can do in VB.