GRPS DTU FAQ summary

　　1、 DTU cannot be connected to the center?

　　1. First determine whether the setting of central demo is normal (analog DTU can be used to connect the center), and then check whether the configuration of DTU is correct, that is, whether the central address and port are set correctly.

　　2. Check whether the DTU signal is normal (check by at command) and whether the SIM card is in arrears.

　　2、 When the settings of DTU and central demo are normal, can't DTU connect to the center?

　　Firstly, we first determine whether the PC running demo in the operation center carries out port mapping (if running on the DMZ server, it does not need port mapping). Thirdly, we determine that the mapped port is not occupied; Is it blocked by a firewall.

　　3、 If the customer does not have a fixed IP, but uses ADSL to dial up the Internet to connect to DTU, but cannot connect?

　　1. Confirm whether the center address configured by DTU is correct (client IP).

　　2. If the central demo is not running on the server, port mapping is required. If ADSL has routing function, port mapping can be done directly on the route; If there is no routing function, you can run port mapping software on the server for mapping.

　　3. When DTU connects to the central demo, all firewalls (windos firewall) and anti-virus software shall be closed.

　　4、 The communication between the center demo and DTU is normal, but the communication with the lower PLC is not up?

　　1. Whether the parameters of DTU correspond to the lower PLC, such as baud rate, parity, data bit and stop bit.

　　2. The communication protocol of PLC is correct (it can communicate with PC first).

　　3. The 485 resistance of DTU and lower PLC serial port does not match (the matching resistance is generally between 10 Ω and 200 Ω).

　　4. Whether the communication interface between DTU and PLC is correctly connected. As shown in the figure:

　　5、 The central demo communicates with DTU normally, but the line often drops?

　　1. Whether the heartbeat packet time of DTU is set correctly. The setting length of heartbeat packet time is related to the local network. Generally, it is set within the allowable time of the local network without data transmission and no disconnection.

　　2. Whether the ID number and SIM card number of DTU are set to be unique. If they are repeated, there will be continuous disconnection and reconnection.

　　6、 When DTU is used as modem, there is an error?

　　1. When the DTU working mode is changed to modem, the working mode (trns) needs to be changed. It is recommended that the customer do not use the DTU with 485 interface.

　　2. The parameter setting shall be correct; Corresponding supported baud rate, no verification, no flow control, 8-bit data bit and 1-bit stop bit.

　　7、 Error in data transmitted by DTU?

　　Check whether DTU and lower PLC equipment parameters correspond, such as parity, data bit and stop bit.

　　8、 DTU cannot enter configuration state?

　　1. Check whether the baud rate of DTU is consistent with that of parameter configuration software (the baud rate of saro3130 is 57600 and that of saro3150 is 115200),

　　2. Check whether the serial port cable is connected normally.

　　9、 The DTU can enter the configuration state, but the at instruction cannot be written?

　　1. Check whether the module and circuit board are well grounded.

　　2. Whether the baud rate of the module has been changed to too large.

　　10、 When applying Kingview in the center, the DTU is always disconnected, but it can be set correctly. Why?

　　1. First establish the channel with the company's central demo and DTU. If the channel is established successfully, then connect to Kingview.

　　2. Check whether the settings of Kingview software are correct, such as check digit Data bits, baud rate, etc.

　　3. Turn off some firewalls and anti-virus software of the center PC.

　　11、 What is the default setting of DTU?

　　1.8-bit data bit / no parity / 1-bit stop bit, baud rate 57600bps

　　2. Data transmission rate: 57600bps

　　12、 How to find the current software version of the module in DTU?

　　Use the command at + cgmr or ATI to view.

　　13、 When using HyperTerminal, you get a strange string when typing the at command?

　　This may be caused by the mismatch between the baud rate of the serial port of the super terminal 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 super terminal.

　　14、 DTU can be installed in windows 3 x. Does it work under operating systems such as Windows 95, Windows 98, windows nt or Linux?

　　DTU has nothing to do with the specific operating system. It works in a fully transparent way. As long as the device sends data to its serial port, DTU can work normally.

　　15、 How to send SMS in at text mode?

　　1. Confirm that at + cmgf = 1. You can get more result code information through at + CSDH = 1.

　　2. Check whether the address of the short message service center is correct, through the instruction at + CSCA?

　　3. Use the following instructions:

　　At + CMGs = "phone number"

　　>Enter text content, ending with Ctrl Z

　　+CMGS：XX

　　OK

　　16、 Why can't you send SMS in at PDU mode?

　　Check whether the PDU mode is correct. Use the command at + cmgf = 0.

　　If you are not familiar with the code of SMS in PDU mode, 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 SMS you wrote)

　　17、 How to check whether DTU has logged into GPRS / CDMA network?

　　The detection method is: in the at command state, enter at + cgatt = 1, return to OK, and then enter at + cgatt? If 1 is returned, it indicates that you have entered the GPRS network; if 0 is returned, it indicates that you have not logged in to the GPRS network. CDMA command is not available for judgment!

　　18、 How to check the GPRS / CDMA signal strength of DTU and the status of SIM / UIM card?

　　In at mode, enter at + CSQ < CF >, and return < * *, ##>, where * * should be 10 ~ 31. The larger the value, the better the signal quality, ## should be 99. Otherwise, check whether the antenna or SIM / UIM card is installed correctly, or check whether there is GSM signal coverage in this area

　　19、 What is the amount of redundant data generated by sending data each time?

　　DTU will generate redundant data only when it establishes a connection with the central end, that is, it sends its own information to the center. In the future, as long as the link is not broken, the sent data will not generate redundant data. The redundant data is 45 bytes, and the specific format is as follows:

　　8-digit hexid (4 digits) + 11 digit telephone number + 0 + login IP address = 41

　　20、 How do I change the baud rate?

　　When modifying the baud rate, (in transparent mode), press the "s" key to enter the setting mode, and enter at + IPR? First query the baud rate, including 38400 under the protocol, but the baud rate of the background serial port is still 57600. At this time, enter the baud rate you want to change, at + IPR = 1200 < CR >, return to < OK >, disconnect under the super terminal, change the background baud rate to 1200, enter the super terminal, directly hit enter, enter the at command, and then you can communicate through the 1200 baud rate. (in non transparent mode), directly input at + IPR = 1200 < CR >, and return < OK >. Similarly, disconnect under the HyperTerminal and change the background baud rate to 1200, which can be used normally.

　　21、 Using its own RS232 cable, it is always unable to establish communication with DTU. Why?

　　A: This is because the connection mode of your own serial port cable is wrong. It is best to use our standard serial port cable. We use 2-3-pin cross connection and 5-pin direct connection, without flow control. Note that the maximum length of the serial port line between the two female heads shall not exceed 15m according to the RS232 standard. Our suggestion is that it should be shorter to facilitate normal data communication.

　　22、 When DTU is running, the yellow light goes out, and then the equipment does not respond?

　　A: if this happens, please refer to the precautions issued by our company with the products!

　　23、 How long does it take from dropping the line to restarting to establish a connection?

　　A: it depends on the actual network conditions at that time, but it usually takes more than ten seconds.

　　24、 We use a fully transparent program for the primary and secondary IP. After the primary IP fails to log in, it will automatically switch to the secondary IP. What should we do if we can't log in to the primary IP again?

　　1. By default, our primary and secondary IP is set to the IP of Shuimu Qinghua. When you modify the primary IP, you do not modify the secondary IP. If the primary IP cannot be connected to the DTU connection center, you switch to the secondary IP (Shuimu Qinghua).

　　2. Before setting parameters, set the function parameters of automatic switching main center; Since the secondary IP is the backup IP, when the primary IP returns to normal, DTU will automatically switch to the primary center.

　　25、 What are the manufacturers of GRPS DTU now? And better technology?

　　Recommend Beijing Juying soar Electronics Co., Ltd., remote data acquisition and transmission integration RTU, CDMA DTU, GSM / GPRS / CDMA data transmission device, data acquisition card, industrial automation control, remote control engineering, Internet of things system, system integration monitoring, GPS vehicle monitoring, GPS satellite positioning, micro power consumption GPRS measurement and control terminal, three meter centralized reading, pipe network, heat network, oil well monitoring Wireless transmission products, 485 distributed data acquisition module, can communication card, instruments and meters. You can also visit: http://www.juyingele.com.cn/jjfa/ The above has application cases in various fields.

　　25、 Why do you always restart frequently and stay in "now restart at state" or other places?

　　A: if all other aspects of your status are normal, it may cause the cable on the motherboard to be loose and not plugged in tightly. You can remove the cable first and then plug it in again, or replace it with a new cable!

　　26、 How to configure GPRS / CDMA DTU?

　　A: you can use the HyperTerminal attached to the operating system or use the serial port test tool to set the serial port attribute as:

　　8-bit data bit / no parity / 1-bit stop bit

　　57600bps

　　None or Xon / XOFF

　　27、 When configuring DTU parameters, how to manually operate instructions to enter at configuration mode?

　　Answer: run the serial port debugging tools such as HyperTerminal, and set the baud rate and other parameters consistent with the current DTU; Press and hold the "s" key of your PC immediately after powering up the DTU. Until it appears

　　“GPRS-1000T Configure program:

　　Use the extended AT commands configure the

　　Arguments needed

　　Input “AT+List” For help.”

　　After "sssss..." appears, enter "at" and press enter to return to OK;

　　Next, you can enter the command to enter the configuration

　　28、 How to refresh the DTU program?

　　Answer: when DTU is not powered on, connect DTU with PC through COM port and run sftdnld Exe file, select COM port and *. In its directory Bin file (its version information will be displayed on the right). Click "start downloading" and power on the DTU. At this time, you can see its installation progress. When it is completed, the update program is successful.

　　29、 How come DTU doesn't respond or has garbled code under the HyperTerminal?

　　A: This is because the baud rate of DTU is inconsistent with that of COM port of super terminal. Just change it to be consistent. In addition, GPRS DTU supports 8-bit data bit and 1-bit stop bit. There is no verification and no flow control. The setting of super terminal should be the same.

　　30、 How to ensure the confidentiality of data when GPRS / CDMA DTU transmits data?

　　A: the data transmission of GPRS / CDMA DTU is based on GPRS / CDMA network, and its security is the same as that of GPRS / CDMA network.

　　31、 If the central end has a fixed IP and the DTU does not bind a fixed IP, but is a dynamically allocated IP, how can the central end distinguish and identify 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 dynamic connection library and demo program to help customers complete the programming of the central end program.

　　32、 Because we don't have many points, we don't want to apply for APN network or fixed IP to increase the project cost. What should we do?

　　A: dynamic domain name resolution can be used. In this way, the domain name of the central end can be set in DTU, and DTU can access the center according to the domain name. Whether the central IP is dynamic or fixed, it will not affect the data transmission, which can not only reduce the cost, but also facilitate maintenance.

　　33、 Can GPRS / CDMA DTU be applied to mobile vehicles? How about environmental adaptability? Is the connection stable when moving faster?

　　A: DTU can meet the requirements of various industrial application environments and can be installed on various mobile objects. However, it should be noted that China mobile GPRS / Unicom CDMA network is not fully covered, and there may be GPRS / CDMA blind spots in some areas.

　　34、 In some application environments, the lower computer may not send data many times a day and does not need to be online in real time. Can the DTU be dormant for a long time to save power and data flow communication costs, but can the central station immediately activate the lower computer DTU and send back data when needed?

　　A: our DTU can realize this remote activation when it is translucent. In the fully transparent mode, the DTU is awakened to send data by calling or sending text messages.

　　35、 Our company has a fixed IP address, but the router obtains this IP. The server in my intranet data center only has intranet IP, but there is no Internet IP. How can I receive data? How can I solve this problem?

　　A: configure on the server or router with fixed IP address and map relevant ports, so that the data of a specified port on the public network can be forwarded to the computer of the data center in the LAN through the mapping function (please refer to the instructions of the router for NAT and port mapping configuration).

　　36、 Why do you see that the connected DTU is disconnected in the central software? Is it true that the DTU is disconnected?

　　1. Observe the online light status of DTU on site and judge whether DTU is disconnected;

　　2. If the DTU online status is normal, check the list maintenance time in the center. This value can be set to be greater than the value that the DTU sends a heartbeat packet every 60 seconds, for example, if it is greater than twice, it is set to 120;

　　37、 Why do you always restart frequently and stay in the "TCP connection error, now reset" error?

　　A: the TCP error may be due to the network condition of your server. You can ping your server first?? (such as ping 218.85.96.210) to see if it is connected If it is disconnected, the server-side network should be solved first. Or the port is not opened by the built-in firewall in the server operating system. Please close this firewall to use.

　　38、 Why do you always restart frequently and PPP errors occur?

　　A: the PPP error may be due to the failure of your SIM card. Please check whether your SIM card is in normal state. There may also be a problem with GPRS network. Please refer to question 7.

　　Note: the online basis for the center to judge the DTU is the value of the current time of the system minus the time when the last data packet is received. If this value is greater than the list maintenance time, the center software will judge that the DTU is disconnected. The processing method can adjust the list maintenance time parameters. At present, the mainstream DTUs mainly include jy-dtu-c and jy-dtu-g