I couldn’t find a specific top-level schematic titled exactly “ICOM CI-V USB Interface Schematic Top” in public databases. However, the CI-V (Computer Interface V) is ICOM’s proprietary control bus for radios (e.g., IC-703, IC-706, IC-718, IC-7300, etc.). A typical USB-to-CI-V interface uses a USB-to-serial bridge chip (FT232RL, CP2102, CH340) combined with a level converter (since CI-V is TTL-level, not RS-232).
Usually auto-sensing, but commonly set to 9600 or 19200 bps in software. Uses Hexadecimal framing starting with "FE FE" (Attention). CI-V Communications Interface-V, Reference Manual 3.2 icom ci v usb interface schematic top
Pins 11 and 12 of the MAX232 are tied together to form the bi-directional CI-V data line. I couldn’t find a specific top-level schematic titled