Hi Beau and all, I've been looking at the serial comms issue, looking promising. Just trying to get my head around C# though....... what "project type" should I be creating in visual studio? I've restricted it to using .NET 2.0 just incase (anyone know what the Archer uses? can it be upgraded to 3.5?) Anyway, THE IMPORTANT BIT: I need to know what brand and model of differential GPS Eureka is using? Also the brand and models of any other (handheld) units they want to use with our system. I need to know this so I can work out which serial standard they are using. Should I email sam/Iliya about this? or do you want to liase with them for me? I just need to know this info ASAP so I can get started on a proper comms library type thing. Cheers, Lorin