1 preface with the rapid development of Internet, networking and more widely applied, on a variety of industrial control equipment of network functionality requirements are also getting higher and higher.
The current requirements in the hope that the industrial control equipment to support TCP/IP, and other Internet protocols, enabling the user to become familiar with the browser to view the device status, set device parameters, or equipment collected data through the network to a Windows or Unix/Linux database on the server. This requires the control system must have two functions: one is to be completed onsite and control of complex tasks, because usually some tasks have real-time requirements; second, the requirements for measurement and control systems and some type of control network connected to realize remote monitoring. Most of the current application and control system, embedded system hardware is 8/16 bit microcontroller; software use of Assembly language programming, since these programs only contains some simple loop processing control processes. Therefore, microcontroller and microprocessor or the position machine communication is typically through an RS232, RS485 to networking. These existing communication network is slow, networking, development difficult. Industrial Ethernet is gradually improving, in industrial control applications get more and more applications. Industrial Ethernet is using the TCP/IP Protocol, and thus facilitate networking and have the advantage of high-speed control network. Now, the 32-bit embedded CPU prices drop and performance indicators, as embedded system provides a wide range of applications. So, the restrictions on embedded systems development bottleneck prominently software. Although from the 1980s onwards, there are a number of embedded operating systems (there are more famous Vxwork, pSOS, Neculeus and WindowsCE, etc), but these private operating system are commercial products, their high price makes many production low end products away from the small company; Moreover, the source code of sealing also significantly limit the enthusiasm of the developer. Embedded system needs is a highly concise, interface and friendly, reliable and widely used, ease of development, multi-tasking and cheap operating system. Today, the industry has reached a consensus that embedded Linux is the trend. Embedded Linux operating system to an affordable, powerful, easy-to-transplant and other features and is being widely adopted, and has become a new force. 2 embedded Linux technology embedded Linux is in accordance with the requirements of the embedded operating system, and designed a small operating system, which consists of a Kernel (kernel) and some make customization of system modules. Kernel generally only a few hundred kB or so, even if combined with other modules and applications, the required storage space is also very small. It has multi-tasking, multi process of system features, and some also have real-time. A small embedded Linux system only needs a boot program, micro-kernel Linux, the initialization process of three basic elements. Running embedded Linux CPU can be x86, Alpha, Sparc, MIPS, PPC, etc. With these chips with motherboards are very small, usually only one PCI card size, and some even smaller. Embedded Linux required memory is not a floppy disk, hard disk, zip disk, CD-ROM, DVD these well known conventional memory, it mainly uses the Rom, CompactFlash, DiskOnChip, M-Systems of Sony MemoryStick, IBM's MicroDrive, and other bodies active in the small (and BIOS on the motherboard is similar in size), and the storage capacity is not too much memory. It's memory you can use the common memory, you can also use the dedicated RAM. Compared with other embedded operating systems, Linux source code is open, the black box technology does not exist. Linux as a crop of software platform system, is likely to become future embedded device product is an excellent resource. Linux born with excellent network origin more has paved the way for the future development of a broad flat road. Therefore, while keeping the Linux kernel system smaller, more stable, more price competitive advantage, on a real-time optimization system kernel, enable it to adapt to industrial control field high real-time requirements. This is precisely why the embedded Linux operating system for embedded industrial control system development. It also enables Linux to become embedded in your operating system. The standard Linux kernel usually resident in memory, each application is shipped from disk into memory. When the program is finished, the memory is freed, the program will be downloaded. In an embedded system, may not have disk. There are two ways you can eliminate the dependency on the disk, one is a simple system, when the system starts, the kernel and all applications exist in memory. This is the most traditional work mode of embedded systems, Linux. The second is linux-specific functionality, because Linux has had the ability to "load" and "Uninstall" program, therefore, an embedded system can use it to save memory. A typical system there are approximately 8MB to 16 MB Flash memory and 8MBRAM and Flash can be used as the file system. Use Flash driver as from Flash to a file system interface is a choice. Of course, you can also use a Flash disk. Use Flash to get out of the system on a disk needs (rely on) have a DiskOnChip technology and CmopactFlash card etc. Used to connect FlashMemory and file system programs are stored as files in the Flash file, can be loaded into memory when needed, this dynamic, as needed, load capacity is a series of features to support other important features. It enables initialization code was released after system boot. In fact, LinuxThere are a lot of kernel to run out of public programs that normally run during initialization, then it is no longer running. Furthermore, these utilities can be used the way they are total one after another in order to run. In this way, the same memory space can be used over and over again to "call in" every program, just as the system boots. This saves memory, particularly those configuration once it is no longer change the network stack. If you set the Linux loadable module features included in the kernel, drivers and applications can be loaded. Because it can check the hardware environment and hardware with the appropriate software, eliminating the use of a program to handle many FlashMemory multiple hardware complexity. Also, software upgrades more modular, can be found in the system run-time in Flash on upgrading the application and load the driver, its configuration and run-time parameter can be used as a data file is stored in a Flash. 3 embedded industrial control networks solution based on embedded Linux for industrial control systems to embedded microprocessor as core to run embedded Linux operating system. Applications can be updated over the network, and may make the man-machine conversation via the keyboard, the data can be displayed by LCD site, important data available file saved in Flash such as Flash memory; data and alarm information available through the serial port transmission up bit machine, or via the Ethernet to Ethernet or publish, Inernet users through network remote monitoring and remote maintenance. More critical is that take full advantage of the Internet has some software and protocols (such as: ftp, http, and Apache PHP MySQL-to-peer applications) builds the foreground data acquisition system for measurement and control system and management system of communication. Figure 1 shows the implementation of the system diagram. The advantages of this approach are: (1) does not need a dedicated communication line is available off-the-shelf INTER-NET network data transfer to any place. (2) is not only able to transfer data signal, or you can transfer audio and video signals. (3) since the current INTERNET Protocol is ready and open to the public, therefore, the use of large to dozens of megabytes of MicrosoftIE browser, or as small as the only 600kB Mosaic browsers can read the data on the network. 4 system design 4.1 hardware design embedded systems hardware platform is the basis for developing an application, the Development Board can be based on IntelRSA-1110 microprocessor architecture. An embedded system hardware structure diagram. The hardware for a network service application chose the Intel series strongARMMCU. StrongARMSA-1110 is a high-performance, low-cost, highly integrated microprocessor. SA-1110 chip internal integration is able to run 206MHz 32-bitIntelRStron-garm * RISC processor and speed up to 100 memory bus and flexible storage controller, supports SDRAM, SMROM and variable-latencyI/O devices, and for system design provides higher storage bandwidth. Because SA-1110 can adapt to a large flow of network applications, thus providing for running Linux hardware support. In addition, SA-1110 also developing onboard a 32 MB SDRAM, 8 MB FLASH, 10baseT Ethernet interface, RS232/RS485 serial ports, i/o interfaces and extend FLASH card memory, etc. About SA-1110 more detailed information please refer to the relevant information.
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