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What are the wireless technologies for the Internet of Things and what are their advantages and disadvantages?

Internet of Things applications have penetrated into our lives, and Internet of Things projects can be applied in all aspects. qcm6125 So, what are the wireless connectivity technologies for the Internet of Things? This paper takes 6 types of wireless technology as an example to deeply analyze the advantages and disadvantages of each kind.

Ethernet

Ethernet is a local area network communication technology. The IEEE 802.3 standard, organized by the IEEE, defines Ethernet technology standards. The content of connection layer protocol is specified, including physical layer, electronic signal layer and media access layer protocol. Ethernet uses twisted pair wire as the medium and can cover a range of up to 200 meters without a relay. qualcomm qcm6490 The most popular type of Ethernet has a data transfer rate of 100 megabits per second, and newer standards support speeds of 1 KMB per second and 10 KMB per second.

The biggest advantage of Ethernet technology is that it is the most commonly used LAN information technology in enterprises in our country, and has gradually developed and replaced other company LAN standards such as token ring, FDDI and ARCNET. Now we need to be familiar with the Internet is all through these problems of large and small Lans connected together, the formation of a global coverage of the network.

Serial communication technology

Serial port is a very general interface used for communication between devices, and is also widely used for communication between devices and instruments. Common serial ports are RS-232 (using 25-pin or 9-pin connectors) and half-duplex RS-485 and full-duplex RS-422 for industrial computer applications.

Serial communication adopts serial mode, that is, serial port bits send and receive byte sequences, usually serial port for ASCII code character transmission. Serial communication is done by three wires: ground, transmit and receive. Serial communication can use the sending line to send data and the receiving line to receive data. It is simple in structure, can achieve remote communication, communication length up to 1200 meters.

advantage

The biggest problem of serial communication is the high penetration rate, serial port PC is still standard, usually in order to more convenient connection to the printer, most of the industrial production equipment have serial ports, those we do not have serial port equipment, in its research and development, common ways and methods can also be connected to the enterprise system development of the computer, Therefore, serial port is the simplest and easiest way for device information to be analyzed and communicated. It is also worth mentioning that the cost management of serial communication is very low if you do not consider the cable connecting the serial port.

shortcoming

The networking capability of serial communication is poor, although we usually use the situation is more stable than the wireless network, but in China's industrial development environment, it is also vulnerable to the electromagnetic impact of the social environment in which the cable is located. There is still a big gap between the communication speed of serial port Ethernet, in general, it is only suitable for low-rate and small data communication.

Modbus

Unlike previous communication technologies, Modbus is generally considered an application-layer protocol standard that uses serial communication, and it does not include electrical specifications. Modbus was first released by Modicon in 1979 for communication using a programmable controller (PLC), and later evolved into Modbus RTU, Modbus ASCII, and Modbus TCP, the latter using an Ethernet interface.

With the wide application of PLC in the industrial field, Modbus has also become the most popular communication protocol in the industrial field. Master Slave communication is adopted, that is, one-to-many connection. One master controller supports a maximum of 247 slave controllers.

advantage

The main advantages of Modbus are: standardization, openness, free use, no license fees, no intellectual property rights.

Support a variety of electrical interfaces, such as serial interface and Ethernet interface, support a variety of transmission media, such as twisted pair, optical fiber, wireless and so on. The framework format of Modbus protocol is simple, compact and easy to understand. Easy to develop and use.

shortcoming

Modbus has the following problems: Poor network capability, only master/slave communication; The network scale is limited, and the number of subordinate controllers limits the network scale. Poor security, no authentication, no permission management, and plaintext transmission make it very dangerous in an uncontrolled environment.