The SX80 module on the Crestron Applications site works fine.
You need a USB-232 dongle to control the SX-20 via serial.
The dongle should have the Prolific chipset.
Check the notes on the module, there are 2 versions
The older version is for the TC 7.xxx.xxx.xxx Cisco software
The newer version is for the CE 8.xxx.xxx.xxx Cisco Software.
It is in the help pdf of the module
RD
rdrygas