Informative Guide: Qualcomm qcser.inf 1. What is qcser.inf ? qcser.inf is a driver information file (Setup Information file) used by Windows to install serial port drivers for Qualcomm-based mobile devices, modems, or embedded modules .
qcser likely stands for Qualcomm Serial . .inf files tell Windows how to install a driver: which files to copy, registry entries to create, and which hardware IDs to match.
This file is part of the driver package that enables communication over virtual serial ports (COM ports) exposed by a Qualcomm device—typically when it is connected via USB in diagnostic, modem, or GPS mode. 2. Common Hardware That Uses qcser.inf You will typically encounter qcser.inf when connecting:
Qualcomm-based Android smartphones (for diagnostic or factory use) Qualcomm 3G/4G/5G USB modems (dongles or embedded modules) Development boards with Qualcomm MDM (Mobile Data Modem) chipsets Vehicle telematics units using Qualcomm modems qualcomm qcser.inf
3. Typical Driver Name When installed, the driver is often displayed in Device Manager as:
Qualcomm HS-USB Diagnostics 9002 (or similar) Qualcomm Serial Port (COMx) Qualcomm QDLoader port (for flashing firmware)
The service name associated with qcser.inf is often qcserial or QCUSBSer . 4. Where is qcser.inf Located? After installation, the .inf file is typically copied to: C:\Windows\INF\qcser.inf Informative Guide: Qualcomm qcser
The associated driver binary (e.g., qcser.sys or similar) may be in: C:\Windows\System32\drivers\
5. Installation Process When you plug in a Qualcomm device in diagnostic mode:
Windows detects a new USB serial device. It searches its driver store or Windows Update for a matching .inf . If qcser.inf is present and matches the hardware ID, Windows installs the Qualcomm serial driver. One or more COM ports appear in Device Manager (e.g., Diagnostic port , NMEA port , Modem port ). qcser likely stands for Qualcomm Serial
6. Hardware IDs Typically Found in qcser.inf The file contains strings like: USB\VID_05C6&PID_9001 USB\VID_05C6&PID_9002 USB\VID_05C6&PID_9091 USB\VID_05C6&PID_9025
VID_05C6 = Qualcomm’s USB Vendor ID PID_ *** = Product ID for different serial functions