I have a device that I made and it has RS485 on it, I put a compatible Modbus firmware in it and wrote a DDE server for the windows HMI front end, which seems to work with the custom HMI I wrote and others that are on the market..
There has been chatter that NetDDE is not supported any more and maybe DDE could be short lived, so I was looking into using the OPC as an option which apparently is used in various interfaces to lab equipment, like Labview etc..
I went to their site and I can't seem to figure out if the minimum support drivers for windows needs to be licensed or not.. I would like to include a OPC server front end for my device. Does any one know about the terms of use?
Jamie