Name: Sitecom USB to Serial Adapter CN 104v2 Driver
Author: Sitecom

Question 1

Installer fails or rolls back?

Accepted Answer

Run the Sitecom/PL2303 installer as administrator. If Windows rejects it, use the latest signed Prolific USB-to-Serial driver; older unsigned packages often fail on Windows 10/11. Reboot before retrying.

Question 2

Device not detected / no COM port?

Accepted Answer

Check Device Manager under Ports (COM & LPT) for “Prolific USB-to-Serial Comm Port” or an unknown device. Try another USB port (prefer USB 2.0), reseat the adapter, and test on another PC to rule out cable/adapter failure.

Question 3

Driver/COM-port conflicts?

Accepted Answer

Uninstall existing Prolific USB-to-serial drivers and hidden COM ports, reboot, then install only the Sitecom CN-104v2 driver. In Device Manager, assign an unused COM port and close software holding the current port.