Clear-Com HX System Frames - Manual (Page 25)

You can also connect the external computer to the matrix frame using a standard PC serial
port to DB-9 RS-232 connector. The maximum recommended length of the cable is
approximately 10 feet (3.04 meters).
Note:
The Eclipse HX-Pico uses a special null-modem DB9 to 3.5 TRS. The Eclipse HX-Median /
HX-Omega / HX-Delta CPU card uses a straight serial cable.
If the EHX computer does not have a serial port, but only provides USB connectors,
adapters are available from computer parts suppliers. However, you will be required to install
drivers for USB-to-serial port connections.
Important note:
Because of differences in PC hardware, operating systems and USB-to-serial converters,
Clear-Com cannot provide a recommendation for a specific USB-to-serial converter.
25 Eclipse HX Matrix Frame Installation Guide