Common basic knowledge of 4G DTU

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Common basic knowledge of 4G DTU [Copy link]

1. What is DTU?

Answer: DTU is the abbreviation of Data Terminal Unit. In a broad sense, during communication, the module units responsible for sending data information at both ends of the data transmission link are called DTU, which performs format conversion and data sorting and verification on the transmitted information. In a narrow sense, DTU generally refers to the lower GPRS/CDMA transmitting terminal equipment in wireless communication. The former is a module, while the latter is a device. The following introduction, unless otherwise specified, refers to the latter (lower transmitting terminal equipment).

2. What are the terms related to DTU?

(1) What are the upper computer and the lower computer?

Answer: The host computer and the slave computer are relative concepts. In communication, there is a pair of devices in a master-slave relationship. The terminal device responsible for submitting information is the slave computer, and the device responsible for processing the submitted information is the host computer. In most cases, the DTU device belongs to the slave computer, and the data center responsible for processing the information returned by the DTU is the host computer. The typical application method is that multiple DTUs correspond to one data center. However, the host computer and the slave computer do not necessarily have a one-to-one correspondence. They can be a slave computer corresponding to one or more host computers, or a host computer corresponding to one or more slave computers. The specific correspondence method depends on the application.

（2）What is a data center?

Answer: A data center refers to a host computer system that collects, aggregates and processes information sent back by lower computers, and performs certain control and management on the lower computers. It includes complete computer hardware equipment and specific complete software functions.

(3) What is fully transparent transmission?

Answer: Fully transparent transmission means no operation or change is made to the IP packet, it is just a simple sending process. In layman's terms, during fully transparent transmission, the format and content of the data do not change before and after sending. The data received by the remote data center is the same as the data collected on site, and the data does not change during the transmission process. If there is any operation or change to the IP packet, it is not fully transparent in the full sense.

3. What is the difference between DTU and wireless Mmodem?

Answer: The first thing to be clear is that DTU and wireless modem are different.

In terms of software design, DTU encapsulates the content of the protocol stack and has an embedded operating system. In terms of hardware, it can be seen as a combination of an embedded PC and a wireless access part. GPRS/CDMA Modem is a physical channel for accessing the GPRS/CDMA packet network. It does not have an operating system itself and must be attached to a computer (similar to a wired Modem in function). It can only perform PPP dial-up connection on the computer operating system. It is usually used in conjunction with a PC. From a certain perspective, DTU is a combination of an embedded PC and a GPRS/CDMA Modem, but it cannot be used as a Modem alone. It completes the function of data protocol conversion and transparent transmission. In terms of use, front-end acquisition equipment or intelligent data equipment usually provides standard data interfaces such as RS232, RS485/422, etc. These front-end user devices are suitable for using DTU, and with the help of the GPRS/CDMA network platform, data communication with the monitoring center can be achieved. GPRS/CDMA Modem needs to be connected to a computer to achieve networking connection. For example, the PC host of the central station can access the GPRS/CDMA network through GPRS/CDMA Modem, thereby forming a central station server to achieve network monitoring and data communication. However, it is difficult to use DTU as a central service station.

4. What preparations are needed before DTU testing?

A: Before testing the DTU, the following conditions are required:

(1) A public IP address or independent domain name;

In some cases, the computers in the test environment cannot have independent public IP addresses and domain name addresses because they are in the internal LAN. In this case, you need to obtain an independent public IP address through dial-up Internet access. You can also set up DMZ host mapping or port mapping on the router in the test environment to enable the computer to penetrate the intranet so that the computer can respond normally to the DTU.

(2) A SIM card with GPRS data service enabled (required for testing GPRS DTU), or a UIM card with CDMA data service enabled (required for testing CDMA DTU);

(3) A desktop computer or laptop with a 9-pin RS232 serial port;

This computer is used to set and adjust the parameters of the DTU. At the same time, during the test, the DTU can be connected as a virtual data source device to send and receive data with the host computer data center through the serial port debugging tool. Of course, this computer can be both a host computer data center and a virtual data source lower computer if condition 1 is met. However, when the second test purpose is used, try to avoid doing so to avoid doubts about the test itself.

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