USB-to-serial adapter

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A USB-to-serial adapter or simply USB adapter is a type of protocol converter that is used for converting USB data signals to and from serial communications standards (serial ports). Most commonly the USB data signals are converted to either RS-232, RS-485, RS-422, or TTL-level UART serial data. The older serial RS-423 protocol is rarely used any more, so USB to RS-423 adapters are less common.