1. What is 4G DTU

       4G DTU wireless transmission module is developed on the basis of GPRS DTU to support 4G communication equipment, compatible with 2G / 3GDTU function, 4G DTU transmission speed is dozens of times faster than 3G DTU, you can even enjoy network freedom, TAS-L17 It integrates various functions such as industrial router, DTU and VPN gateway. High-performance industrial-grade 32-bit communication processor and industrial-grade wireless module, with embedded real-time operating system as the software support platform, while providing RS232 and RS485 (or RS422) interfaces, can be directly connected to serial devices to achieve data transparent transmission function.

Second, what is the principle of 4G DTU

The communication between the DTU and the server is carried out by the 4G DTU end (client). The server did not respond to the DTU based on the feedback sent back or the communication was accepted. The DTU end and the service end form an application system based on 4G communication and Internet technology network communication with each other. Compared with DTU terminal equipment, the network server terminal equipment is equipped with more complicated mobile phone applications, which can accept all communication requests made by DTU terminal equipment, and check the communication status of the link anytime, anywhere, so as to realize the application of instant data collection and database service. .

The DTU needs to know the IP address and port number of the server beforehand, and then it can initiate a communication request. Once the communication is established, there is no difference between the server and the DTU.

The IP address of the server can be either a public IP (fixed IP) or a dynamic domain name obtained through a domain name resolution server.

The port number of the server generally matches the special mobile phone application running in the server. For example, the port number TCP 21 is used by the FTP service project, and TCP 80 is used by the dynamic web server (Http). In other words, server-side mobile phone applications are suitable for pushing and receiving data based on special server ports.

Generally, the IP address obtained by the 4G DTU terminal is the intranet IP address randomly assigned by the network operator, and the Internet network can be accessed through the mobile operator ’s gateway. Special attention should be paid to the NAT (network Address translation) The port mapping service has a short time limit, so if you need to maintain bidirectional communication, you must set up 4G-DTU heartbeat packets sent regularly to maintain NAT port mapping.

3. Features of 4G DTU:

Connection method: Support 4G, 2G, 3G, network

Transmission mode: transparent data transmission, configuration software protocol

Transmission protocol: Support TCP, UDP, MQTT, AT command control

Data Center: Support dynamic domain name and fixed IP address access, multiple backup data center

Efficient: cache function to ensure data is not lost

Flexible: Support real-time online, support multiple remote wake-up methods such as SMS, phone and serial data

Manageable: DTU can be configured and queried remotely via SMS

Easy maintenance: support local firmware upgrade

4. Four core functions of 4G DTU:

1. Internally integrated TCP / IP protocol stack

The 4G DTU encapsulates the PPP dial-up protocol and TCP / IP protocol stack and has an embedded operating system. From the hardware, it can be seen as a combination of an embedded PC and a wireless 4G MODEM; it has 4G dial-up Internet access and TCP / IP data The function of communication.

2. Provide serial data bidirectional conversion function

4G DTU provides a serial communication interface, including RS232, RS485, RS422, etc. are all commonly used serial communication methods, and 4G DTU design mostly serial port data into a "transparent transmission" mode, that is to say 4G DTU can Convert the original data on the serial port into TCP / IP data packets for transmission without changing the original data communication content. Therefore, 4G DTU can be connected with various user equipments using serial communication, and there is no need to modify the user equipments. It greatly facilitates the transmission process and does not require complex protocol conversion.

3. Support automatic heartbeat and keep permanent online

One of the advantages of 4G DTU equipment is that it supports permanent online 4G terminal equipment. Therefore, typical 4G DTUs are designed to support permanent online functions. This requires DTU to include automatic dialing on power-up and heartbeat packets to maintain permanent online (when long time When there is no data communication, the mobile gateway will disconnect the DTU from the center. A heartbeat packet is a small data packet sent by the DTU and the data center before the connection is disconnected to keep the connection from being disconnected.) Equipped with watchdog technology, double protection equipment, automatic reconnection, automatic redial and other features when the device is disconnected.

4. Support parameter configuration and permanent storage

As a communication device, 4G DTU has a wide range of applications. In different applications, the IP address and port number of the data center and the baud rate of the serial port are different. Therefore, 4G DTU should support parameter configuration, and save the configured parameters in the internal permanent storage device (usually FLASH or EEPROM, etc.). Once powered on, it will automatically work according to the set parameters.