I have a device with usbser.sys as the device driver.
when i plug in the device into computer ,It is working properly in Device Manager ,I right click the device and got the properties message “The device is working properly” , and i try to open this device by Createfile, It failed ,and i found that in SERIALCOMM register key that is no com port number mapped .
As i know that the USB to Serial driver will create a register key to map the device , at what cases will cause to create register fail ,but successful shown in device manager ?Is that matter with device ?