Design And Research On Dual-channels Proportioning Weighing Instrument Based On GSM/GPRS

With the rapid development of science and technology increasing levels of automation, weighing technology has been developing rapidly, weighing instrument digitization, network, intelligence have made great progress such as communication, weighing instrument research and development have entered a new stage.With the development of coal, metallurgy and material, proportioning belt weighing and its automatization proportioning system develop toward rapidness, exactness, stableness and mightiness. So further introduction of new technologies, the development of automatic weighing system, the development of dynamic weighing accuracy, and the development of to strengthen their network function is the key in all countries. In China, the weighing apparatus industry begins to take shape, but high-end technology products get behind. Actively developing products with independent intellectual property rights for the development of Chinese high-grade weighing scale industry is of great significance. The issue was aimed at the expansion project in Shanxi Coking Coal Ltd proportioning belt weighing and the control system design, the paper obtains the help and fund of the National Development and Reform Commission high-tech industry projects in 2004 and the National new instruments projects (2005ED630022) in 2005.It has two emphases in this paper. First, to meet the security and reliability of data acquisition system, we use dual-channels signal acquisition module to achieve a two-way operation and handling.Second, it focuses on the GSM/GPRS wireless network data transmission systems. In recent years, rapid development of mobile communication technology, the mobile phone popularization rate is rising year by year; meanwhile, it expands its data transmission business, including wireless Internet connection business. Computer is not the only Internet terminal. Portable cell phone to the mobile equipment has been represented as the most important and the most common terminal. Mobile communication technologies, the combination of Internet provides a stable, convenient remote control for weighing system. China mobile communications system integrates the internet realized the remote control to proportioning belt weighing. Based on the analysis of the characteristics of GPRS and SMS, SMS and GPRS are chose to build systems, this method is a leader in terms of technology, performance reliability.The overall design includes five parts:The first part of the paper introduces the proportioning belt weighing design requirements, whole structure, and system components. In accordance with the needs, the instruments will communicate with PLC, apply to Profibus field bus transports coal proportion of coal PLC system into the instrument, and 4～20mA current signal is sent.The second part introduces hardware design principle and its application. Particularly describe the hardware components and functions. Mainly include the followings: ADuC845, INA118 instrument amplifier, the pulse signal acquisition module, DS1307, keyboard interface, 4～20mA current output, digital output, power supply systems and GPRS wireless network data transmission system and so on.The third part introduces the communication manners and its principle, hardware and software based on GPRS wireless network data transmission system, SMS has the advantage of wide coverage, GPRS has the advantage of high transmission rate, therefore, combining SMS and GPRS weighing data monitoring system with the greatest coverage and maximum capacity of users is the best option under the current conditions. In the region covered by GPRS network, the scene instruments monitoring data can be transmitted using the GPRS network, on the other hand can use SMS to transmit.The fourth part introduces the proportioning belt weighing instruments software program design and PC interface software program. Software program includes the main function, system initialization, flow capacity calculation, PID adjustment, communications tasks and GPRS wireless data transmission system. PC interface is designed under the Visual Basic 6.0 environment, to achieve data requests, data acquisition, and data preservation functions.The fifth part of the paper tests performance and concludes the result that meets GB/T 7724-1999, meanwhile, put forwarding the prospect and opinion to the instrument and its communications functions in the future.