1. Introduction to DTU and RTU
DTU (Data Transfer Unit), the Chinese name is the data transfer unit, used to convert serial data into IP data or IP data into serial data, through wireless communication networks (3G, 4G, 5G, WiFi, NB, Lora), Use HTTP, TCP, UDP, MQTT and other protocols to transmit data to the wireless terminal equipment of the remote server to complete functions such as data monitoring, local logic control, remote upgrade, and fault alarm. DTU is widely used in various industries such as smart city, smart agriculture, smart manufacturing, electric power, meteorology, water conservancy, geology and so on. The intelligent IoT gateway is the core entrance of the IoT system. Choosing a powerful, stable, reliable, and easily expandable IoT gateway is one of the key links in the implementation of the IoT project.
RTU (Remote Terminal Unit), the full name in Chinese is the remote terminal control system, which is responsible for the monitoring and control of on-site signals and industrial equipment. RTU is the core device that constitutes an enterprise's integrated automation system. It is usually composed of signal input/output modules, microprocessors, wired/wireless communication equipment, power supplies, and shells. It is controlled by microprocessors and supports network systems. Through its own software (or intelligent software) system, it can ideally realize the functions of telemetering, remote control, remote signaling and remote adjustment of primary instruments on the production site by the central monitoring and dispatching system of the enterprise.
Both DTU and RTU can collect sensor data and realize remote data transmission through 4G network. RTU is a bit more complicated than DTU. It has some control functions and can perform analog and switch input and output operations. DTU is to realize simple data transparent transmission.
、 、 DTU
DTU (Data Transfer Unit), the full name of the data transfer unit, is a wireless terminal device specially used to convert serial port data into IP data or convert IP data into serial port data for transmission through a wireless communication network.
Features:
(1) Rapid and flexible networking, short construction period and low cost;
(2) Wide network coverage;
(3) Good security and confidentiality performance;
(4) Link support is always online, billed according to traffic, and low user cost;
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The more professional DTU ( ZL-LTE-300 ) also provides some extended functions, mainly including:
- Support HTTP/TCP/UDP/MQTT communication protocol;
- Support Alibaba Cloud/Tencent Cloud/China Mobile IoT/DevelopLink platform access;
- Support automatic reading and writing and conversion of MODBUS RTU protocol, directly upload json to the server, support periodic polling and change upload;
- Support custom heartbeat package, registration package, support magic value;
- Support data center domain name resolution;
- Support remote parameter configuration;
- Support remote and local firmware upgrade;
- Support differential upgrade DFOTA, CDN acceleration;
- WEB query displays the base station location, trajectory information, etc. of each device.
Through Windows, Linux, Web visual debugging tools, users do not need to program, can complete the application with the least and simplest configuration.
ZL-LTE-300 can also provide users with secondary development functions; for example: remotely implant scripts and customize any fields so that users can develop and design DTU according to their actual needs, and improve the functions of DTU products.
Three, RTU
Remote Terminal Unit (Remote Terminal Unit, RTU), a special computer measurement and control unit with a modular structure designed for long communication distances and harsh industrial site environments. It combines terminal detection instruments and actuators with remote control centers The main computer is connected to have remote data acquisition, control and communication functions. It can receive operating instructions from the main computer and control the actions of the terminal actuators.
RTU can be implemented with a variety of different hardware and software, depending on the nature of the site to be controlled, site environmental conditions, system complexity, data communication requirements, real-time alarm reports, analog signal measurement accuracy, status monitoring, and equipment Regulation control and switch control. Because the data transmission protocol, information structure, and error detection technology adopted by each manufacturer are different, each manufacturer generally produces a dedicated RTU supporting the SCADA system.
Features:
(1) The communication distance is long, and a variety of communication ports are provided at the same time to meet the different communication requirements of scattered applications and locals.
(2) The CPU has strong computing power and provides large-capacity program and data storage space, which is suitable for on-site operations and secure storage of large amounts of data.
(3) Adapt to harsh temperature and humidity environment, working environment temperature is -40~+85℃.
(4) The modular structure design is easy to expand.
Fourth, the difference between DTU and RTU
1. Function
Both DTU and RTU collect and upload data through a wireless network.
DTU generally supports RS232 and RS485 interfaces, transparent transmission through the operator's network, using some simple protocols to package serial data into IP data for remote transmission. The RTU has the function of acquisition and control. There are more interfaces and the protocol is relatively more complicated. For example, after the analog variable is collected, it is converted into a digital format through A/D.
In summary, the main difference between RTU and DTU is: DTU only provides a link, you can set the serial port parameters to connect to the collection device, while RTU is equivalent to DTU+ collection , and some can directly collect switches and analog signals. Simply put, DTU is data transmission equipment, and RTU is data acquisition equipment. The division of labor between the two is clear and easy to distinguish. You can choose the corresponding product according to your actual needs.
2. Hardware
RTU's hardware mainly includes functional modules such as CPU, memory, and various input and output interfaces. These modules are integrated into the circuit board, and the functional modules of the RTU are connected through the circuit board wiring. The CPU is the central system of the RTU controller, responsible for processing various input signals, and after arithmetic processing, the output is completed. The memory is the RTU memory system, used to store various temporary or permanent data.
DTU hardware components mainly include CPU control module, wireless communication module and power supply module. The advantages of DTU include: rapid and flexible networking, short construction period, and low cost; wide network coverage; good security and confidentiality; link support is always online, charging according to traffic, and low user cost.
3. Application
The main function of DTU is to wirelessly transmit data from remote devices back to the back-end center. To complete the data transmission, a complete data transmission system needs to be established. In this system include: DTU, client equipment, mobile network, back-office center. At the front end, the DTU and the customer's equipment are connected through the 232 or 485 interface.
After DTU is powered on and running, first register to the operator's network, and then go to establish a SOCKET connection with the background center set in DTU. The back-end center is the server of SOCKET, and DTU is the client of SOCKET connection. Therefore, only DTU cannot complete the wireless transmission of data, and it needs to be used with the cooperation of background software. After the connection is established, the front-end equipment and the back-end center can carry out wireless data transmission through DTU, and it is two-way transmission.
DTU has been widely used in power, environmental protection, LED information release, logistics, hydrology, meteorology and other industries. Although the application industries are different, the principles of application are the same. Most of the DTUs are connected to industrial equipment, such as PLCs, microcontrollers and other automation products, and then establish a wireless communication connection with the background.
The most direct application of RTU is in the water conservancy industry. RTU is directly connected to the water level gauge; it can also be used in temperature and humidity monitoring, heating network monitoring, gas monitoring, environmental protection testing, weather monitoring, traffic control and other industries.
参考：
【1】https://baike.baidu.com/item/DTU/183474?fr=aladdin
【2】https://baike.baidu.com/item/%E8%BF%9C%E7%A8%8B%E7%BB%88%E7%AB%AF%E5%8D%95%E5%85%83?fromtitle=RTU&fromid=7830288