Summary of DTU related issues

1. What are the functions and differences between RTU and DTU?

DTU only provides links, and serial port parameters can be set to connect acquisition devices. RTU is equivalent to DTU + acquisition. Some can directly collect switch analog signals.

2. The wireless DTU is transmitted to the server through GPRS, which is always stable, but suddenly the data is not uploaded, and the SIM card fee is still high.

The DTU cannot be connected. There may be:

1. Abnormal connection with upper computer

2. The connection of lower computer is abnormal.

The connection of the upper computer is not normal. There may be a problem with the setting of demo in your center, which should be consistent with the parameters of DTU.

The central demo connection is normal and cannot be connected with the lower computer. You can

1. Let the user equipment communicate with the PC normally first

2. Whether the parameters of DTU correspond to the lower user equipment, such as baud rate, parity, data bit and stop bit

3. The 485 interface for DTU has 485 matching problem with the lower user equipment (the matching resistance is generally between 10 Ω and 200 Ω).

4. Whether the communication interface between DTU and lower user equipment is correctly connected. If it is 232 interface, jumper shall be used.

3. DTU communication server sends data to DTU. DTU can receive data and send it to the server with local computer. The server can also receive data, but the lower computer is connected to DTU. What are the reasons why the server cannot receive the data sent by the lower computer? Is the damage of the data line eliminated?

1. Whether the data bit, check bit, baud rate and DTU of the lower computer are consistent, and whether the data protocol uniformly uses TCP or UDP protocol.

2. Make sure that the SIM card you use for DTU uses enough money and opens relevant GPRS or 3G services.

3. Check whether the selected port is correct and try to restart the device.

4. Check whether the SIM card is in arrears

4. Differences between DTU and GPRS modules

They all transmit data together. DTU can only send useful data without managing at instructions. All these are processed by DTU. GPRS module, you have to be familiar with the at command before you can send data. In short, DTU is convenient, simple and stable. You can use it when you use it. GPRS module takes some time to get started, and it is troublesome to keep it always online.

5. How DTU realizes wireless communication

Data path: lower computer -- serial port -- DTU -- GPRS -- Internet (IP) -- central PC

6. What is the DTU measurement and acquisition device cabinet and what is its function?

Collect field data, and then conduct wireless data transmission through DTU.

7. Can DTU only transmit data to the receiving end with fixed IP address?

To establish a connection with the background, DTU must tell the IP address or domain name of the receiving end. Otherwise, DTU doesn't know who to connect with. After the mobile phone logs in to the GPRS network, mobile will temporarily assign an IP address of mobile content to the mobile phone, which is different from the address on the Internet. If you tell DTU this IP address, DTU cannot establish a connection with him. However, if you buy the SIM card of mobile customized APN node and put it in DTU and mobile phone respectively, you can establish direct communication between DTU and mobile phone.

8. DTU can send and receive data through the network connected to Telecom. Why can't it send and receive data through the network connected to Netcom?

1. Confirm what type of DTU is, CDMA or GPRS?

2. Then check whether the SIM card has opened the corresponding Internet service?

3. Check what your computer uses to surf the Internet? Telecommunications? Or Unicom? In some cases, broadband providers shield the information of other operators. This situation is relatively rare when it does exist.

9. The router is connected with DTU equipment and then connected to WAN. What does DTU equipment mean?

The full name of data transmission 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 wireless communication network.

10. How to configure wireless transmission device DTU with computer

First of all: in hardware, you need a 232 to 485 serial port conversion connection line

Secondly: after confirming the hardware connection, open the HyperTerminal to configure the serial port, as shown in the figure below, and configure it according to the above parameters

Bits per second set to 9600 data bits set to 8 parity set to no stop bit set to 1 data flow control set to none

(you can also find a free serial port software and DUT configuration software on the Internet for testing)

Finally: you need to know which core communication module this DTU uses, understand the at command of changing the module, and configure it through the input of at command.

11. DTU has 232 serial ports and 485 ports. What is the difference between them in application? Is the serial port cable different?

They are all control lines. 232 transmission distance is short and 485 transmission distance is long. 485 is two lines, which conforms to the 485 protocol. It is divided into positive and negative poles. In short, the difference is these. If you have to use 232 and the distance is far, you can add a converter.

12. When DTU is used to form a data acquisition system, if the central end is a LAN, how can a machine in the LAN listen to and send and receive terminal data?

The data center can transmit data in response to the connection initiated by the wireless data transmission DTU.

13. What is CDMA DTU?

DTU is wireless data transmission equipment. CDMA DTU refers to the equipment that transmits data through CDMA network. Wireless data transmission DTU is divided into GPRS DTU and CDMA DTU.

14. A GPRS wireless data transmission network needs to be established. The front end is DTU equipment and the back end is the server received by the data center. The server is a fixed public IP. What devices need to be connected to complete the networking connection with the front-end DTU?

Open a port on the public network, configure the IP and port number into the DTU device, and then you can transmit data.

15. DTU data center networking structure

1) Internet access is adopted in the data center, and broadband ADSL access mode is adopted. This mode has the advantages of large bandwidth and economic cost. The disadvantage is that the security is poor and the delay is slightly larger than that of dedicated line access. LAN shared Internet access is adopted, which is basically similar to ADSL access, but it should be noted that port mapping is required during access. Use telephone line dial-up Internet access. This method has narrow access bandwidth. Therefore, it is only suitable for networking with less points and small amount of data.

2) The mobile company's access to the data center adopts the wireless network operator (referring to China Mobile) to provide channel access. In fact, this method has the following connection modes: the special line access mode of the mobile company's computer room is adopted, which has large bandwidth (generally 2m) and is very good for delay and security, but the price of renting this special line is relatively expensive. It is especially suitable for users who need high safety factor, such as banks and POS unit networks. This method is also recommended when there are many sub stations. GPRS wireless access mode is adopted, which connects a gprs modem in the data center and dials up the Internet through the PC in the data center. The advantages are networking speed and economic cost. The disadvantages are narrow bandwidth (GPRS uplink 10kbps, downlink 40kbps) and large delay. This method is often used in testing. Note that the APN card needs to be used in the actual project preparation.

16. What is the difference between remote data acquisition terminal and DTU?

DTU is mainly used for remote data transmission through 2G and 3G networks. Automatically send data to remote single or multiple monitoring centers through serial port!

The remote data acquisition terminal is a device that can transmit data through microwave, 2G, 3G, satellite and other media.

17. What does DTU mean by converting data into IP data?

DTU 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 wireless communication network.

18. What is the difference between DTU and wireless mmodem?

In software design, DTU encapsulates the content of protocol stack and has embedded operating system. In hardware, it can be regarded as the connection of embedded PC and wireless access. GPRS / CDMA modem is a physical channel for accessing GPRS / CDMA packet network. It does not have an operating system. It must be attached to the computer (similar to wired modem in function). PPP dial-up connection can be carried out on the computer operating system. It is usually used in combination with PC. From a certain point of view, DTU is the combination of embedded PC GPRS / CDMA modem, but it can not be used as a modem alone. It completes the functions of data protocol conversion and transparent transmission. In use, front-end acquisition equipment or intelligent data equipment usually provide standard data interfaces, such as RS232, RS485 / 422, etc. These front-end user equipment are suitable for DTU and realize data communication with the monitoring center with the help of GPRS / CDMA network platform. GPRS / CDMA modem needs to be connected to the computer to realize networking connection. For example, the PC host of the central station can be connected to the GPRS / CDMA network through GPRS / CDMA modem, so as to form a central station server to realize network monitoring, data communication, etc. DTU is difficult to use as a central service station.

19. What is the DTU serial handshake protocol? What are RTs and CTS?

It refers to the man-made serial communication. Both parties confirm to establish a connection

RTS is the input of the module, which is used by MCU to inform the module whether MCU is ready and whether the module can send information to MCU. The effective level of RTS is low.

CTS is the output of the module, which is used to inform MCU whether the module is ready and whether MCU can send information to the module. The effective level of CTS is low.

20. DTU establishes a TCP link. In order to realize remote collection and transmission, it connects to the designated PC through routing settings.

DTU connection must be an IP address that can be recognized by the external network. If you use the internal network IP, you must do port mapping.