subject: Cdma 1x-based Remote Monitoring System - The Electronics Industry - China Ent Medicals Disposables [print this page] 1 IntroductionIn existing industrial control systems, commonly used in information transmission are: digital microwave radio data transmission, fiber optic cable, cable cable, digital microwave radio transmission will be several transmission distance and frequency of license restrictions, cable fiber and high cost of cable networks, not suitable for monitoring point is very scattered and transmission distance and circumstances.
For monitoring objects dispersed, the lack of organic links between monitoring nodes, monitoring a relatively small amount of information, real-time requirements and low features, CDMA1X provides a good means of information transmission.
CDMA 1X CDMA2000 willing to refer to the first phase (rate higher than the IS-95, less than 2MB / s), supports 308kb / s data transmission, the network part of the introduction of packet switching, can support mobile IP services, is CDMAIS-95 in the existing system developed a new carrier services, the purpose is to provide CDMA packet data services form.
As CDMA1X coherent demodulation using a reverse, fast forward power control, transmit diversity, Turbo coding and other new technology, its capacity much higher than the IS-95, from the theoretical analysis results, if used to transmit voice business, CDMA1X total capacity of the system is IS-95 system 2 times, if used to carry data services, CDMA1X total capacity of the system is IS-95 system, 3.2 times, CDMA1X theoretical bandwidth of up to 300kb / s, the current practice bandwidth of about 100kb / s or so (two-way symmetrical transmission), in this channel to provide TCP / IP connection, can be used for Internet connection, data transmission applications.
2 based on CDMA 1X wireless
Communicate2.1 network scheme Wireless data transmission systems are generally data service centers, communications networks and data terminal component, considering the volume of business data, security, reliability, and cost factors such as network conditions, using the following networking mode: communication server to the public Net fixed IP or domain name access to the fixed Internet, CDMA Data Terminal Unit (DTU) on the power, the initiative to establish a connection with the communication server, communication server, if no fixed IP, the software can be obtained by installing a fixed peanut shell domain, this scheme has low cost, stable communication quality, safety, moderate, and reliable operation.
2.2 wireless data transmission principle
According to the network scheme, the uplink data transmission works as follows:
(1) lower computer through RS232 serial data transmission DTU;
(2) DTU data labeled as TCP / IP packet, sent to the wireless network;
(3) TCP / IP data packet by packet data service node system, transmission to the Internet, and to find the Internet on a specified data service center (communication server);
(4) communication server to pass data to the host computer and store history database.
Downlink data contrast with the above process, will not go into the system communication structure diagram shown in Figure 1.
3 System Design 3.1 PC design Host computer system, including real-time monitoring and historical database of two parts.
Real-time monitoring system used Wonderware's InTouch system, mainly to achieve the following functions: system management functions; data processing: including data query capabilities, data storage, data reporting function of time; alarm features include: real-time response capabilities, alarm linkage processing functions, alarm setting function, alarm recognition function, alarm memory function, operation control, the historical database used Wonderware's IndustrialSQLServer, mainly to achieve the following functions: statistical, reporting capabilities, historical data query functions, historical data, graphs, printing .
3.2 slave in Lower computer use ABBAC31 series PLC, including the CPU module and I / O modules, CPU to receive one or more designated monitoring center of the equipment operation control command, through the I / O modules on the device perform the appropriate operation control action, return to the operating results of the monitoring center, lower machine to achieve the following main functions: data acquisition capabilities, data query capabilities, time reporting function, the operation control function.
3.3 CDMA data transmission interrupted
CDMA data transmission interrupted electricity use Shenzhen Technology Development Co., Ltd. Macro CDMA H7710DTU the terminal has the following characteristics:
(1) H7710DTU directly RS232/422/485 interface for the user's data devices provide transparent, full-duplex, on the other data transmission channel.
(2) ordinary GPRS / CDMAModem usually attached to the PC, a virtual dial-up Internet access, using the resources of PC, data transceiver and protocol conversion, H7710DTU built-in automatic network connection and protocol processing module, no computer support background.
(3) H7710DTU can achieve point - point, point - more, the center - such as multi-point data transmission on the transmission delay is generally less than 1s.
(4) H7710DTU the start will automatically attach to GPRS or CDMA networks, your data center with the establishment of communication links, at any time the data sending and receiving user data device.
(5) H7000 mobile data communication can not depend on the data exchange center operator interface device, anytime, anywhere via Internet network that covers all of China's virtual private network, mobile data communications.
CDMA H7710 DTU crash in the parameters must be set before use: CDMA1X network login user name and password, communication interface parameters, communication server, or a fixed IP address and port communications server name, DTU-line work and so on.
3.4 Design and implementation of communication server
Communications server is the hub of the entire system, mainly to achieve data transfer between different protocols, communication server design is based on OPC standards, OPC may be understood as the process control of the object linking and embedding (OLCfor ProcessControl) is Microsoft's operating system application program interface developed for a technology, based on Client / Server model, in order to achieve the whole system of communication, the communications server software need to install 3; Wonderware's OPClink, IOServer company IOServer, CDMAServer. The working process and the communication server software, as shown in Figure 2 between the management.
Following communications were about 3 on the server communications features and applications software.
3.4.1 OPClink
OPClink is working under the Windows platform, application software, the main role is to transfer by agreement
