Remember the system prompts before you unplug the USB flash drive? 'Point this pop-up device', many devices are now beginning to convert to USB interfaces, such as the previous parallel printers, RS 232 devices, all through technical updates and interface conversion changes. For more convenient USB.
However, some devices have been abandoned by the time during the evolution of the industry because they are still. What are the benefits of being plugged into a USB device? Hot plugging is hot swapping. This feature allows users to leave the system without shutting down the system. Remove and replace hardware without turning off the power supply to improve system scalability and flexibility.
Early hot-plugging appeared in the server field to improve the ease of use of the server. The USB that is nearest to us is also designed to facilitate the connection of external devices, allowing external devices to be used without shutting down the system. Replacement, greatly enhanced the convenience, think about the previous PS/2 interface, change the system to restart, how much trouble. However, some USB interfaces are not produced according to design standards, can not meet the design requirements, may cause damage This all starts with the physical structure of the USB interface.
USB also pay attention
The most common USB male head internally consists of four data lines, with two left and right power supplies, and two middle data lines. The power contacts are longer than the data contacts.
Therefore, when the USB device is unplugged, the USB device will disconnect the data line first. After the data is disconnected and transmitted, the power will be disconnected. This will protect the USB device. If all the contacts inside the USB male are designed At the same length, if the data is disconnected from the power supply or the power supply is disconnected first, it is very likely to damage the data.
It's not a big deal that ordinary USB devices are easily plugged in or plugged in. If it is a device that contains important data, it is highly recommended that you eject the device and then physically unplug it.
Controversial device interface
According to past practice, I often hot-swap the display interface, but they all support hot-pluggable technology. Some video interfaces do not support hot-plugging at all. HDMI is a video interface that we most often contact. In theory, HDMI is hot-swappable. According to the design standards, HDMI must have anti-static function, but some low-cost products will be omitted, it is very likely to damage the device, whether it is using a good wire or ordinary Wire, I still don't recommend it.
In addition to HDMI, another high-performance interface is DP. The full name is DisplayPort. At the beginning of the design, the hot-swap function was added. One of the pins is used to detect the connection status, so that the device can be notified to interrupt transmission at any time. However, DP's hot-plugging is also related to the wire, 9.9 class of wire is still a bit honest.
In addition to the above two, the VGA and DVI interfaces are still in use. People who are constantly exposed to the computer know that both sides of the two interfaces are equipped with screws to fix anchor points. According to the inertia of thinking, everyone may think that there are two. The fixed point is only used for reinforcement, but it is not. The two interfaces are not hot-pluggable by nature. Therefore, this method is used to strengthen the connection and avoid accidents.
The correct method of plugging and unplugging is to ensure the correct connection of the device before shutting down, and to perform plugging and unplugging after the system is completely powered off. In addition to the exposed interfaces on the outside of the chassis, the device interfaces inside the chassis cannot be hot-plugged at all. , For example PCI-E with video card inserted; SATA with hard disk connected; memory and CPU not to think about. In the future we must pay attention to the hot swap of some devices to avoid accidental loss.
