.net components for PLC communications

Does anyone know where to purchase VB.net components for PLC communications? I use the Vhmi COM software now with VB6 but I would like to start using .net for my PLC apps.

http://www.opcsystems.com/

Uses OPC server so you need an OPC server available, but I've used it & reccomend it highly.

I am just about completed the development of the .NET Allen Bradley DF1 protocol control. I put it out for free as open source. It has more capabilities than any of the ones available for purchase. It is fully .NET 2.0 managed code and written in Visual Basic.

If you are using SLC's or micrologix with serial communications, then try this out:

http://sourceforge.net/projects/abdf1/

Thanks for the information. I'll be sure to try your software Archie.

I also have an app coming up for OPC so that link is valuable.

I'd like to write some protocol stuff myself but just not enough time in the day so I just buy it. If my customers don't "see" results on a daily basis well I'm sure you know how that is....