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Silicon Labs CP210x USB-Serial Adapter

The Silicon Labs CP210x family (CP2102, CP2104, CP2105) is the USB-to-serial bridge built into many modern radios (Icom, Yaesu) and is also sold as standalone adapters. For ORLP it provides a virtual COM port for CAT control and exposes RTS/DTR lines usable for hardware PTT keying. Why it matters: When a radio or interface needs serial CAT or RTS/DTR PTT but has no native USB, a CP210x adapter bridges it. The CP2105 is a dual-UART part — it presents two COM ports from one chip, which is how radios like the FT-710 and FTDX10 expose CAT-1 and CAT-2. Drivers: Windows needs the Silicon Labs VCP driver; Linux and macOS detect it automatically (cp210x kernel module). A solid, well-supported default choice.