What is it?

This is a TTL level and DC power USB-to-serial adapter board, but with complete galvanic isolation between the host and the target.

This board uses an isolated DC-DC converter module to supply fully isolated 5 or 3.3 volt power to a target system from the host, plus it uses isolated logic transfer chips to move the serial port signals across the isolation barrier. The target is supplied with DC power and full serial port signals at 5 or 3.3 volt levels with complete 1+ kV galvanic isolation from the host.

The host connection is a USB-C socket. The UART chip is the CY7C65213, which requires only CDC class drivers. All of the essential serial port signals (TXD/RXD, CTS/RTS, DTR/DSR, DCD & RI) are passed across the galvanic barrier.