I've developed a small interface board for the HAMWARe controller AT-502, AT-515 and AT-651B. This interface boards supports RS232 and CI-V communications and can be directly mounted into the controller chassis.
There are two DB9 connectors for RS-232 communication and two 3,5mm phone jacks for CI-V communications. You can find the circuit diagram in the user manual.
The PCB production files and more information can be found on my github repository.
I have a small number of converters on request ... checkout here.