从Excel发送命令到应用程序？ COM？

I wrote a device controller (rs232) and it is being used successfully, however users want to view data and control the device (or perhaps communicate through my program) from Excel. I dismissed DDE as an option and found that RTD (IRtdServer) is probably a good start (though no way to send data back to the "server" from the real time data client). I wrote a device controller (rs232) and it is b