What is the purpose of the 5V DC output on CP adapters that are powered over USB?
Answer:
For adapters powered over USB (typically single, dual and quad port), the 5V DC output can be used to power an external device.
This removes the need to have an additional power supply for the external serial device.
Please refer to the datasheet (available from the product page for your model of converter at https://us.connectiveperipherals.com) for the maximum current ratings of the 5V output.