If the USB device is not recognized
The appearance in the nineties of the USB standard incomputing technology can be compared with a quiet revolution: finally, the hardware and software developers "remembered" the simple users of personal computers, realizing the long-awaited possibility of "hot" connection of devices.
For many years served faithfullyparallel (LPT), serial (COM) and even PS / 2 interfaces did not allow high-speed connection with the connected device, did not support the self-tuning technology, peripherals were connected only with the power removed. The USB standard (serial bus) that replaced them eliminated all these shortcomings. However, as it sometimes happens, soon after the appearance of a large number of corresponding devices, the user's instructions on the error "The USB device is not recognized" began to appear on the Web. Since the advent of the tire has passed more than ten years, and the problem has remained. Many still face the system message "the device is not recognized". Let's try to understand what is happening: we will point out the possible causes and ways to restore efficiency.
All devices for serial bus are conditionallycan be divided into wired ones that use wire (printers, scanners, cameras, telephones, external hard drives) and wireless (flash drives) to connect to the port connector. The error "USB device is not recognized" is most often found in devices of the first type. This happens in the following way: after connecting the wire and power supply, an error message appears next to the clock on Windows systems. If at the same time to see the status of the device manager, then it is displayed there as an "unknown composite USB". One of the most common reasons for this behavior is mechanical. Any break in the conductors in the wire or a soldering violation in the plug - and the message "USB device is not recognized" will not take long to wait. Very common problem. And, we draw your attention to the fact that the wire can fail "in itself". For example, yesterday, a working printer, to which no one touched, today does not work, and the system reports "USB-device is not recognized". It is necessary to reconnect the plug to the other connector of the bus and, if not help, replace the wire. Sometimes the contact clamping in the connector is partially broken - the result is similar (that's why we recommend switching to another port). But this case is typical for an already working device. Everything is a bit more complicated if the connection is made for the first time.
Flash USB drives that do not use wire,Also not immune from such a mistake. In this case, you should check with another connector. In some cases, the cause of the problem is trivial - the driver that does not exist in the system. The solution is simple - to install the device support program (phone, camera, etc.).
All modern motherboards supportstandard USB 2.0. In BIOS, at the same time, you can make an adjustment to the settings of the controller, choosing support for versions 2.0 and 1.0 (1.1), or only the second version. Obviously, when you activate "USB 2.0 Only" the device of the previous standard will not be able to work properly. We read the instruction and check the corresponding settings.
By the way, in the flash drive the error message on connection can be caused by the controller firmware failure. It is often corrected by reprogramming.