【正文】 ［18］袁月峰，陳典紅，附 錄1 外文復(fù)印件USB in data acquisition system applicationIn the industrial production and in the science and technology research various professions, frequently controls using PC or the labor machine carries on gathering to each kind of has very many places to need to carry on gathering to each kind of data, like fluid position, temperature, pressure, frequency and so the monly used gathering way is through the data acquisition board card, monly used has the A/D card as well as 422, 485 and so on the total forming block card.. Not only uses the board card the installment trouble, easily the engine case in the environment disturbance, moreover as a result of the puter slot quantity and the address, the interrupt resources limit, not impossible to hang meets very many the universal serial bus (Universal Aerial Bus, is called USB) the appearance, has solved above these conflicts well, very easy to be able to realize the low cost, redundant reliable, the multispot data acquisition. introduces USB is some PC big manufacturer, like Microsoft, Intel and so on one kind of serial munication standard which in order to solve which day by day increases the PC peripheral and between the limited motherboard slot and the port contradiction formulates, has declared a position since 1995 on Comdex widely has supported until now for each PC factory. Now produces PC has nearly all provided the USB connection, Microsft Windows98, NT as well as MacOS, Linux, FreeBSD and so on the popular operating system all increased to USB the support. USB the system constitution USB system mainly by the master control regulator (Host Controller), USB Hub and the USB peripheral (Peripherals Node) is posed the system topology, as shown in Figure 1. USB main merit 　　(1) speed of USB highspeed and lowspeed two ways, the main mode of highspeed mode, rate of 12 Mbps, and does not need to adapt to some very high throughput and realtime equipment, If the mouse, USB also provides lowspeed, rate of Mb / s. (2) equipment installation and configuration easy to install USB devices without reopen chassis, Modified installation of the equipment do not need to shut down the puter. All USB devices support hot pluggable, the system automatically on its configuration, discard the previous dialup jumper and switch installed.(3) easy to expand through the use of Hub Dialup can be extended up to 127 peripherals. Standard USB cable length of 3 m (5m lowspeed). Hub or through the repeater can enable peripherals reach 30 m distance. (4) to use USB bus power supply provides maximum voltage up to 5 V, 500mA current.(5) Use of a total of four USB flexible transmission mode : Transmission control (control), ATM (Synchronization) interruption of transmission (interrupt), the bulk transmission (bulk), to meet the needs of different2. uses the USB transmission the data acquisition equipment. hardware position　A practical USB data acquisition system including the A / D converters, microcontroller and USB munication interface. To expand its uses, can also add more analog switches and digital I / O ports. System of A / D and digital I / O is designed to be able to follow the traditional design methods, According to the acquisition accuracy rate, channel, as well as in several elements to choose a suitable chip, the design should give full attention to the antijamming performance, In particular, the A/D Acquisition especially. In microcontroller and the USB interface, there are two choices, A microcontroller is used with an ordinary USB dedicated munications chips. ASIC is now the more popular of National Semiconductor Corporation USB N9602, the SL11 ScanLogic other. The author has adopted the 89 panies Atmel microcontroller and USBN9602 decoder chip and system, achieved good results. This program design and debugging more trouble, the cost is relatively high. Another option is using USB munication with the MCU. With USB application of the increasingly widespread, Intel, SGS Tomson, Cypress, Philips, and other chip manufacturers have introduced a USB munication interface with the MCU. These microprocessing capability, and some have their own on multiple A / D, constitute a system of circuit is simple, convenient debugging. Electromagnetic patibility, and thus, using USB interface with the MCU constitute USB data acquisition system better solution. However, as with the USB interface, these chips past the development system is usually not patible, need to buy a new development system, the higher investment. software constitutionWindows98 providing a wide variety of USB device drivers, But it seems no one is specific data acquisition system, we must address specific equipment to prepare the driver. Although the system has a lot of standard interfaces function, However, it remains Driver USB development of a most difficult things, Windows DDK is usually used to achieve. There are many thirdparty software vendors to provide a variety of tools for generating, Compuware, as the driver works, Blue Waters, the Driver Wizard. They can easily within a few minutes of generating highquality USB driver. Equipment SCM Program for the same difficulties, but no one manufacturers to provide the automatic generation tool. Establishment of a stable, wellSCM process is directly related to equipment performance and must be given full attention. These two procedures are of concern to developers, users of much concern. Users concerned about how efficiently through the click of the mouse to operate the equipment and how to handle the collection and analysis of large amounts of data ing in, it also must have highquality software users. Software must be user friendly interface, powerful data analysis and processing capabilities and to provide users with redevelopment of the interface .3. realizes the USB longdistance range gathering data transmissionTransmission distance is limited USB ap