Writing and reading a PLC

Hello everyone, I am still somewhat new to VB 2008 trying to get all the basics down. I want to start a project that will require a little more time and work. I've been searching around a little bit looking at some third party applications to write to and read a PLC (programable logics controller). Someone had recomeneded using SCADA which includes an HMI, but i believe that is somewhat expensive. I'm also dont want an application that requires the purchase of speacial drivers, which we know can be expensive and troublesome. I dont need anything incredibly fast either, i dont think i would be drawing or writing to the plc more than once every 5 or 10 seconds, but that is a rough estimate at this time. If you have any experience with anything like this some suggestions or ideas are very much appreciated. Thankyou in advanced for your feedback.

serial?

I will be using ethernet. There will probably be anywhere from 1-5 plc's that will be on a standalone network using a hub or some kind of switch. Hope that helps :)

What make and model PLC are you want to communicate with?

I'd choose a Beckhoff BC9000 PLC. I've built libraries for doing most functions via Ethernet. Let me know if you need any help with this :)

Hello, can you send me your libraries? in what language is it?