With the development of science and technology, the company’s attendance system has also undergone constant upgrading, gradually becoming high-tech, and it is almost impossible for people to escape. The most widely used is now the fingerprint identification technology. It is widely used in various integrated information management systems, which greatly improves the company's attendance quality. The traditional system of punching cards often presents loopholes and irrational places. The current fingerprint attendance system is a single-chip microcomputer system and only provides RS232/485 serial communication. In general, it cannot complete long-distance network data transmission. As far as the current technology is concerned, TCP/IP libraries are provided in various operating systems and programming language environments, and writing TCP/IP applications is as simple as writing a serial port program through a dedicated protocol conversion device (TCP/IP). The protocol-a serial communication protocol) can also be called a serial server to enable real-time network data transmission.
In general, the serial server has three main operating modes:
One is a serial port server that uses a virtual serial port communication mode: In this mode, one or more converters establish a connection with a computer to achieve bidirectional transparent transmission of data. The following converters are managed by the virtual serial port software on the computer. A virtual serial port can correspond to multiple converters. N virtual serial ports correspond to M converters (N<=M). This mode is suitable for RS232 device connection of serial device controlled by computer.
One is a serial port server based on the network communication mode: In this mode, the application program on the computer writes a communication program based on the SOCKET protocol and directly selects and supports the SOCKET protocol on the converter setting. The serial port server accomplishes storage control of a connection-oriented RS232 link and connectionless Ethernet-oriented communication data. The system processes various data, processes the serial port data stream from the serial port device, and performs format conversion. It becomes a data frame that can be propagated in Ethernet; it judges the data frame from Ethernet and converts it into serial data to respond to the serial device.
One is the peer-to-peer communication mode: In this mode, the converters are used in pairs, one as the server and one as the client, establishing a connection between the two to achieve bidirectional transparent transmission of data. This mode is suitable for modifying the bus connection between two serial devices into a TCP/IP network connection. More serial server information, please click http://
USB3.0 provides a standard interface for all kinds of devices that are connected to PCS or audio/high-frequency devices.The theoretical transmission speed is up to 5Gbps. HUB is commonly known as a hub, which is used to connect multiple computers or network devices in a network using a star topology. The USB 3.0 Hubs is an upgrade of the USB 2.0 Hubs. The transmission rate of the USB2.0 is 480Mbps, and the transmission rate of the USB3.0 is 5Gbps. The maximum transmission speed is 10 times that of the USB2.0, and the transmission speed is faster.
The USB 3.0 hub provides a quick and easy way to connect all the peripherals you use on your desktop. You can connect 2 external monitors, gigabit Ethernet ports, headphones/speakers, USB printers and scanners, keyboards, mice and other peripherals with a single USB 3.0 cable to your computer for up to 5Gbit/s external storage access (10 times faster than USB 2.0). USB HUBS can do split, but not evenly. If, as the subject says, you only have two devices, and the two devices are transmitting at the same time and taking up as much bandwidth as possible, then you end up with two devices each taking up 50% of the bandwidth. Due to the fast theoretical speed of USB3.0, even if divided into four parts, the theoretical bandwidth of each port is still as high as 1Gbps, and the number of converted bytes is close to 100MB/s, which is still a very high bandwidth.
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