It looks like it is done by DDE to the HRD remote serial server on port 7806, VU2SJD (Sanjay) of web4hrd fame uses a dll (jDDE.dll) in his program.
(DDE = Dynamic Data Exchange)
Well, in the future I may write a DDE client, but I'm not in any hurry to get that working in RCForb. DDE has been unsupported by Microsoft for a long time (years) and they do not recommend using it for exchanging data between programs. It still exists in Windows for legacy support...(from what I understand, Im not always right, hihi)
Since Simon is not developing HRD anymore, I dont really know whats going to happen with it. I do know 5.1 should be out sometime before 2011 or maybe in Jan of 2011. Lets hope the new owners dont break anthing

Time to start bringing in more native support for radios in RCForb!