OPC driver/Software question

Started by Maynard A. Philbrook Jr. October 18, 2014

 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?