DTU refers to the data terminal equipment (DataTermanitunit), which can be understood as the lower GPRS transmitting terminal. When communicating, the DTU must exist at both ends of the link for transmitting data. Under its action, the format conversion and data sorting of the transmitted information are performed. Test.
GPRS/CDMA network and product FAQs (updated at any time) 1. What is the default setting of DTU?
A: The default settings are as follows: 8-bit data bit/no parity/1 stop bit, baud rate 57600bps data transfer rate: 57600bps
2. How to find the current software version of the module in the DTU?
A: Use the command AT+CGMR or ati
3. When using HyperTerminal, get a strange string when typing the AT command?
A: This may be caused by the mismatch between the baud rate of the serial port of the HyperTerminal and the baud rate of the serial port of the module/DTU. Use AT+IPR? To detect the DTU/module serial port rate, and then detect the configuration of the HyperTerminal.
4. Can DTU work under Windows 3.x, Windows 95, Windows 98, Windows NT or Linux?
A: DTU has nothing to do with the specific operating system. It uses a fully transparent working mode. As long as the device sends data to its serial port, the DTU can work normally.
5. How to send short messages in ATTEXT mode?
A: First, confirm AT+CMGF=1, you can get more result code information through AT+CSDH=1. Check if the address of the short message service center is correct. By commanding AT+CSCA? Then, use the following command: AT+CMGS=“phone numberâ€> enter text content, end with CTRLZ+CMGS:XXOK
6. What is the reason why I can't send short messages in ATPDU mode?
A: Check if the PDU mode is correct. Use the command AT+CMGF=0. If you are not familiar with the short message code in PDU mode, then you can do the following: AT+CMGF=1 (set TEXT mode) AT+CMGW (write a short message) AT+CMGF=0 (set PDU Mode) AT+CMGR (read the short message you wrote)
7. How to check if DTU has logged in to GPRS/CDMA network?
A: The detection method is: in the AT command state, enter AT+CGATT=1, return OK, and then enter AT+CGATT? If the returned is 1, it means to enter the GPRS network. If the return is 0, it means that the GPRS has not been logged in. The internet. CDMA has no instructions to judge!
8. How to check the DTU's GPRS/CDMA signal strength and SIM/UIM card status?
A: In AT mode, enter AT+CSQ
9. What is the amount of redundant data generated each time data is sent?
Answer: DTU only generates redundant data when establishing connection with the central end, that is, sends its own information to the center. After the link is not broken, the transmitted data will not generate redundant data. The redundant data is 45 bytes. The specific format is as follows: 8-bit HEXID (4 digits) + 11 digits phone number + 0 + login IP address = 41
10. How to change the baud rate?
A: When modifying the baud rate, (in transparent mode) press the “s†key to enter the setting mode, input AT+IPR? First query its baud rate, including 38400 under the protocol, but the background serial port baud rate Still 57600. Then enter the baud rate you want to change, AT+IPR=1200
11. With my own RS232 cable, I can't establish communication with DTU at all times. Why?
A: This is because your own serial cable connection is wrong. It is best to use our standard serial cable. We use 2, 3 pin cross, 5 pin direct connection, no flow control. Note that the longest length of the serial cable between the two female heads cannot exceed 15 meters according to the RS232 standard. Our advice is to be able to be shorter to facilitate normal data communication.
12. When the DTU is running, the yellow light is off, and then the device has no reaction.
A: If this happens, please refer to the notes issued by our company with the product!
13. How long does it take to disconnect from reboot to reboot?
A: This depends on the actual network conditions at that time, but it is usually about a dozen seconds under normal circumstances.
14. We use the full transparent program of the primary and secondary IP. After the primary IP login fails, it will automatically switch to the secondary IP (Shuimu Tsinghua), and then login to the primary IP. What should I do?
A: This is because our primary and secondary IPs are set to the IP of Shuimu Tsinghua by default. You modify the primary IP and forget to change the secondary IP to the same IP as the primary IP.
15. Using the full transparent master and slave IP program, switching from the primary IP to the secondary IP, and then switching from the secondary IP to the primary IP, takes too much time, can you not use the secondary IP, or the primary and secondary are set to the same?
A: If you don't want a secondary IP, you can set the primary and secondary IPs to be the same. DTU will automatically determine whether you are using a single IP or primary and secondary IP to save time.
16, why has been frequently restarted, and always stay in the "TcpConnectionerror, NowReset" error?
A: A TCP error may be caused by a problem with the network status of your server. You can ping your server first (such as ping218.85.96.210) to see if it is connected. If it is in a non-connected state, This first solves the server-side network. Or the firewall that comes with the server operating system does not open the port. Please close this firewall to use it.
17, why has been frequently restarted, PPP error?
A: A PPP error may be caused by a failure of your SIM card. Please check if your SIIM card is in a normal state. There may be a problem with the GPRS network. Please refer to Question 7.
18, why has it been restarted frequently, and always stays in and always stays at "NowReStartATState", or somewhere else?
A: If all other aspects of your condition are normal, it may be caused by the looseness of the cable on the motherboard. You can remove the cable and plug it in again, or change a new cable!
19. How to configure GPRS/CDMADTU?
A: You can use the HyperTerminal that comes with the operating system or use the serial port test tool to set it. The serial port property is set to: 8 data bits/no parity/1 stop bit 57600bps or XON/XOFF
20. Why can't I enter AT configuration mode when configuring DTU parameters?
A: Recently, many users have reported that they cannot enter the AT configuration mode when configuring terminal parameters. You can press and hold your PC “S†button before powering up. Until "GPRS-1000TConfigureprogram: UsetheextendedATcommandsconfiguretheArgumentsneededInput" AT+List appears
21, how to refresh the DTU program?
Answer: If the DTU is not powered, connect the DTU to the PC through the COM port, run the sftdnld.exe file, select the COM port, and the *.bin file in the directory (the version information will be displayed on the right), click “Start Download†After that, power on the DTU, then you can see the installation progress, and the update process is successful.
22. How does DTU have no response or garbled under the HyperTerminal?
A: This is because the baud rate of the DTU is inconsistent with the baud rate of the COM port of the HyperTerminal. Just change it to be consistent.
23. When GPRS/CDMADTU transmits data, how to ensure the confidentiality of its data?
A: The data transmission of GPRS/CDMADTU is based on GPRS/CDMA network, and its security is the same as GPRS/CDMA network.
24. If the central end has a fixed IP, and the DTU is not bound to a fixed IP, it is a dynamically allocated IP. How does the central end distinguish between which DTU transmits the data?
A: In our DTU we can set the ID number or identify it according to the SIM card number. We will provide a dynamic link library and DEMO program to help the client to complete the programming of the central program.
25, because we do not have a lot of points, do not want to apply for APN network or fixed IP to increase project costs, what should I do?
A: Dynamic domain name resolution can be used, so that the central domain name can be set to the DTU, and the DTU can access the center according to the domain name. No matter whether the center is dynamic or fixed, the data will not be affected, which can reduce the cost. Also easy to maintain.
26. Can GPRS/CDMADTU be applied to mobile vehicles? What is the environmental adaptability? Is the connection stable when moving faster?
Answer: DTU can adapt to various industrial application environment requirements and can be installed on various moving objects. However, it should be noted that China Mobile GPRS/Unicom CDMA network is not completely covered, and some areas may have GPRS/CDMA blind areas.
27. In some application environments, the lower computer may not send data for a small number of times a day. It does not need to be online in real time. Can the DTU be in a dormant state for a long time to save power and data traffic communication costs, but when the central station needs it, Can I immediately activate the DTU of the lower computer and send back the data?
A: Our DTU can achieve this kind of remote activation in a translucent case. In the fully transparent mode, the DTU sends data by calling or sending a text message.
28. Our company has a fixed IP address, but the router obtains this IP. The server in the data center of my intranet only has the intranet IP, there is no external IP, so how to receive the data, how to solve this problem? ?
A: Configure the server or router with a fixed IP address and map the relevant port, so that the data of a specified port on the public network can be forwarded to the data center computer in the LAN through the mapping function. Refer to the router's manual for NAT and port mapping configuration.
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