I am designing an application that requires me to access devices connected to the machine. We will have control of the machine, meaning control of the software and OS installed.
I know in the past one might suggest active-x controls, I was wondering is there a better solution? I have looked into Silverlight as an alternative, but not found much information supporting that design approach
If you are speaking of the client's machine, Silverlight will not be of much help since it is sandboxed. In fact browsers and plugins are so locked down, that I think you should change your approach (maybe deploy your own client app, instead of using a browser/web app?)
Well, in theory, there's tcp support in Silverlight and so you could use that to talk to a local piece of software. In reality, tcp won't connect to the local machine unless you're in debug mode. So, that's a problem.
What people have been doing is creating a local WCF service and communicating with that. If you take this approach, don't forget to host up a cross-domain file as well.
I'd just add that if you can control what's on the client machine, WPF may be a much more straightforward answer :)