DTU basic knowledge of the Universal manual __ Hardware

1, what is DTU. A: DTU is a shorthand for data terminal equipment (Terminal unit). Broadly speaking, in the communication, the transmission of data at both ends of the link is responsible for sending data information module units are called DTU, under its role in the transfer of information to the format conversion and data collation check. Narrowly speaking, 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, if not specifically stated, refers to the latter (the next launch terminal).
2, the DTU related to the noun explanation.      1 What is the host computer and the next machine. A: The host computer and the next machine is a relative concept, in the communication, there is a master-slave relationship between the equipment, is responsible for submitting information to the terminal equipment is the next machine, responsible for processing the information submitted by the computer. DTU equipment is the next machine in most cases, and the data center responsible for processing DTU return information is the host computer, the typical application is multiple DTU corresponding to a data center.   But the host computer and the next machine is not necessarily one by one corresponding, they can be a subordinate machine corresponding to one or more host computer, can also be a host computer corresponding to one or more subordinate machines, the specific corresponding way to depending on the application.      2 What is the data center.   A: Data center refers to the next machine return information collection, summary and processing, and the next machine to carry out a certain control and management of the host computer system, he includes a complete computer hardware equipment and specific complete software functions.      3 What is full transparent transmission. A: Full transparent transmission is the IP packet does not make any operation and change, but simply send the process. In general, the full transparent transmission, the data before and after sending the format, content does not change, the remote data center received data and the data collected at the scene is the same, the data in the transmission process does not change, if the IP packet has any operation and change, is not the full sense of full transparency.
3, DTU and wireless Mmodem what is the difference.      A: The first thing to be clear is: DTU and wireless modem is not the same. In the software design, DTU encapsulates the protocol stack content and has embedded operating system, which can be regarded as the interface of embedded PC Plus wireless access part. GPRS/CDMA Modem is a physical channel to access the GPRS/CDMA packet network, which itself does not have an operating system, must be attached to the computer (functionally similar to a wired modem), on which the PPP dial-up connection can be made on the computer operating system, usually in conjunction with the PC. In a way, DTU is a combination of embedded PC and GPRS/CDMA modem, but it cannot be used as modem alone, it completes the function of data protocol conversion and transparent transmission. In use, front-end acquisition equipment or intelligent data equipment, usually provide standard data interface, such as RS232, rs485/422, these front-end user equipment suitable for the use of DTU, with the help of GPRS/CDMA network platform, to achieve and monitor the central end of the data communication. GPRS/CDMA modem needs to connect the computer, realize the network connection, for example, the PC host of the central station can access GPRS/CDMA network through GPRS/CDMA Modem, thus constituting a central station server, realizing network monitoring, data communication and so on. And DTU is difficult to use as a central service station.
4, DTU need to do before the preparation of work. A: Before testing the DTU, the following conditions are required: 1. A public network IP address or a stand-alone domain name; In some cases, the computer in the test environment is unable to have an independent public network IP address and domain name address because it is in the internal LAN, so it is necessary to obtain independent public network IP through dial-up Internet, You can also set up a DMZ host mapping or port mapping on a router in a test environment to enable the computer to penetrate the intranet so that the computer can respond properly to the DTU. 2. An open GPRS data Business SIM card (test GPRS DTU must), or a open CDMA data business UIM Card (test CDMA DTU must); 3. A desktop computer or notebook computer with 9Pin RS232 serial port; This computer is used to set up and adjust the parameters of the DTU, while in the test, can connect DTU as a virtual data source equipment, through the Serial debugging tool and the host computer data center to send and receive data. Of course, this computer in the case of satisfying the condition 1 can be both the host computer data center, but also the virtual data source next machine. But when it comes to the second Test, try to avoid doing so so as not to doubt the test itself. 4. A complete set of test software, complete test software including: DTU matching special parameter setting software, serial debugging software, host computer data center demo demo software. GPRS DTU 5, configure the terminal's default setting is what. A: 8-bit data bit/no parity/1-bit stop bit 9600bps none or Xon/xoff to properly select the COM port connected to the DTU.
6, DTU module how to address.  Its address and how the port is set. A: The address and port number of the service center can be stored in Sim/uim card or DTU flash in advance, we can configure and store in DTU Flash via DTU Configuration tool, or configure the data by GPRS/CDMA mobile phone and store it in the SIM card to establish communication with the service center.
7, if you know the status of DTU information, such as the status of the network. A: At present, mainly through the DTU panel (or circuit board) on the led to indicate that 1, when the net LED is often bright, indicating that the DTU module is working properly, and has found the GSM network; When the net LED is not bright, indicates that the GSM network has not been found. 2, for the terminal is not logged on the GPRS/CDMA network, users can be judged by the flash indicator flashing. If the flash light is flashing continuously, you are still logged on to the GPRS/CDMA network, and if the flash light is on, the GPRS/CDMA network is not logged on. 3 If the terminal is transmitting data, the user can judge by the blinking of the ACT indicator. If the act indicator is flashing continuously, the data is transmitted, and if the act LED is not lit there is no data transfer.
8, DTU Why can not communicate with the DSC (data center). Answer: Follow these steps to check whether the net LEDs are illuminated steady (flashing only if registered to the GSM network); Check that you have inserted a Sim/uim card correctly; Check that you have requested permission from your network vendor; Check signal strength: Enter configuration status, select Enter ( View the product specification, at least greater than 12. If the signal is weak, check your antenna status and the network status of your location, and check the power supply (see power requirements).
9, in the collection system composed of DTU, how to distinguish the data sent from different terminals. A: DTU embedded TCP/IP protocol stack, with the socket communication function, and provide transparent data transmission channel, users can only set some parameters will be embedded system directly connected to the Internet to achieve interconnection and interoperability network.                                    Monitoring Center Socket Port Monitoring program is responsible for listening to the connection request of the acquisition terminal, when the monitor hears the connection request, establishes the communication link, originally is responsible for listens the socket still to carry on listens, the communication link establishment may exchange the data arbitrarily. In the socket mode, because of the human intervention, the realization of this function is relatively simple. In sieralnet mode, you can do the following: 1 port identification mode: Each terminal defines a port (1024-65535). Central multithreading listens for these port data at the same time and identifies different sources of data based on different port numbers. In general, listening for hundreds of ports at the same time is not a problem for your current computer. 2 Data Frame way: The terminal sends the data packet to the central unified port, these packets must carry the terminal ID number, the center identifies the different terminal data through the different IDs.
10, how to make customers in the actual application of better use of DTU. A: Under normal circumstances, when the user set a good DTU parameters, into the serialnet mode, DTU will automatically remember all the current state and parameters, even if the power off will not be lost, in addition, the DTU has the disconnection function. This makes DTU like a transparent transmission channel, so long as the user provides a stable power supply, there should be no problem. But in the practical engineering application, the user also proposed the higher request, for example said that continuously unattended work several years not to have the problem, forever maintains the communication line the unimpeded and so on. To this end, our DTU users have the following recommendations: 1 use DTU reset PIN or short-circuit switch power off reset function (for existing old version of the product). Given the many uncertainties in wireless communications and the high reliability requirements of users, it is recommended that users increase this part of the circuit to ensure foolproof. 2 Many users mentioned how to detect the communication line in Serialnet mode. Some companies ' products are detected by sending heartbeat data, and in order to ensure the transparency of the user's channel, there must be a DLL link library at the center end. We think that such a way is not desirable, the existence of DLLs so that the data has a layer of links, for UNIX, or Linux platform for the central node to have a special link interface, there are some security risks and instability factors. Our product does not use heartbeat pack, it is the standard socket interface directly open to the user, so that almost all programmers can be very convenient in different platforms to achieve data transceiver function. The function of the heartbeat pack we think that the solution is more appropriate in the application layer, which can be combined with the user's application is relatively close, but also reasonable to reduce data traffic. When the user is in the socket mode, the monitoring of the data link can be detected either through a heartbeat packet or ping. When the heartbeat is found to be problematic, it can be resolved by means of a reset.
11, in the use of DTU composition data acquisition system, the central end can use dynamic IP access address. Answer: Yes. Center can through dynamic domain name resolution software will be dynamic address and a domain name state, DTU can support the domain name resolution function.
12, how to use the dynamic IP access address when composing the data acquisition system with DTU. A: If the central end is a specific server, the specific settings are as follows: 1 Center: Apply for ADSL or telephone line access to Internet services. Apply for dynamic IP domain name Resolution service (DDNS) and obtain the domain name. (for example, "Peanut Shell" program, Http://www.oray.net/products/PeanutHull.asp has introduced and downloaded). Install and set up the "Peanut Shell" program at each boot. ADSL or phone lines are dialed into the Internet. 2) terminal (DTU): Set DTU DNS server address. (AT+TSDNS) for serialnet mode, set the remote IP address (at+tsripaddr) to write to the assigned domain name. For socket mode, use AT+ISTCP: address or domain name to establish a connection.
13. When using DTU to compose data acquisition system, if the center end is a LAN, how to let a machine inside a local area network listen and send and receive terminal data. A: You can use the virtual server capabilities of the gateway router to map the port you are listening to on any computer in the local area network so that the specified port data arrives at the gateway router and is sent to this computer. See the manual for the use of the shared device and router.
14, the use of GPRS/CDMA transmission mode and TCP/IP protocol, data center How to determine the data is collected by the terminal upload data. A: DTU adopts the port identification method, each terminal defines one port (1024-65535). Central multithreading simultaneously listens to these port data and identifies different sources of data according to different port numbers, which accurately identifies data that is uploaded by the acquisition terminal. In general, listening for hundreds of ports at the same time is not a problem for your current computer.
15, if the terminal an Internet, the network immediately assigns a dynamic IP, so that in different time intervals, the same terminal IP number is different, data center how to distinguish, identify data warehousing operations. A: DTU embedded TCP/IP protocol stack, with the socket communication function, and provide transparent data transmission channel, users can only set some parameters will be embedded system directly connected to the Internet to achieve interconnection and interoperability network. Monitoring Center Socket Port Monitoring program is responsible for listening to the connection request of the acquisition terminal, when the monitor hears the connection request, establishes the communication link, originally is responsible for listens the socket still to carry on listens, the communication link establishment may exchange the data arbitrarily.
16, please simply signal the data center to use from the mobile company to connect the data line, the entire system configuration and budget. A: The use of data line (DDN) than ADSL access mode of higher costs, the specific cost to the mobile company, as well as local DDN service provider inquiries. But the access mode is safe and reliable, and the data delay is small.

17, the current widespread use of DTU have.
Answer: Jy-dtu-c and Jy-dtu-g
18, we now need a GPRS products, please ask if you can provide 80kbps~150kbps system solutions. A: According to our test in different cities, currently China Mobile provides GPRS bandwidth generally can only provide 20~40kbps bandwidth. Please consult your local mobile operator for different areas of bandwidth in different cities.
19, our company has a server and fixed IP address, but considering the stable operation of the server is usually not allowed to install other applications on the server, so the GPRS data center system is not allowed to install on the server, how to solve this problem.      A: If your server is running Windows Server, you can easily configure it on a server with a fixed IP address, mapping the associated port from gprs/ Data from a specified port on an Internet network forwards data from this port to a computer in a local area network that has a GPRS data center installed (Download port mapping and configuration management usage instructions) through the mapping feature. If your server is running Windows NT Server, install WinRoute Pro to do the appropriate mapping configuration. If your server is running Linux, see the Linux operating system configuration instructions for NAT and port mappings. If your network uses Cisco or 3COM routers, refer to the router's instructions for the NAT and port mapping configuration.