To start off with, I want to thank Jan for his patience and persistence in helping me with my issue.
He worrked hard to help, even generating a special diagnostic tool within the firmware to try and find the error.
In the end it was an oversight on my part that caused the issue.
To the point, The Green Heron RT-21 has both an RS-232 DB-9 port and a USB port (serial port emulator) on the rear panel.
I connected the RC-1216H to the DB-9 and forgot to disconnect the USB cable from the other computer so both were connected at the same time, thus causing an internal port conflict in the Green Heron. This showed up as no status from the RC-1216H even though when I commanded the software to turn the antenna, the commands reached the GH RT-21 and it turned!
Lesson learned!!
I am now a
very satisfied customer of the RC-1216H, it's working great!