A method for reading/writing a chip in a USB type-C cable comprises converting a read/write command into unstructured vendor defined message (UVDM) that is conforming to a USB power delivery specification. Such UVDM will be delivered to the chip via a type-C configuration channel interface. The chip analyzes the UVDM to acquire the read/write command and reads or modifies the content of a non-volatile memory in the chip according to the read/write command. Due to use of the type-C configuration channel interface, which is inherent in the USB type-C cable, to read/write the chip, it needs no extra interface which otherwise increases costs.