Design Of Multi-Channel Data Acquisition Module Based On LAN

With the innovation and development of microprocessor technology, sensor technology are rapidly developed and popularized. New demands are also suggested for the front end of information technology—data acquisition module. Today, the rapidly developed data acquisition module is widely used in the modern social life and industrial production control. With its increasingly wide applications, more and more types of signal are acquired and measured, and some new requirements have been put forward on the sampling rate, channel number, acquisition accuracy, data transmission, as well as other functions of acquisition module. Some of the existing data acquisition modules often have problems, such as small number of channels, low acquisition accuracy and negligible range of acquisition voltage. Many traditional products use serial port or special interface to transmit data, however, they're unable to perform remote control acquisition nor high-speed transmission of large quantity of data. The modern Ethernet technology is capable of overcoming the limitations from traditional ways of data transmission. By utilizing uniform standards and equipment, reduction is established on the difficulty and cost of acquisition system wiring. The modern Ethernet technology is simple to operate and maintain, additionally, it is capable of high speed, good compatibility, and other characteristics, which is suitable for a large number of high-speed signal transmission.To solve the problems mentioned above, a high precision synchronous acquisition module which collects the voltage range of signal that has the function of gear selection,a single module with 8 channels was designed. The control of function and data transmission of this module uses LAN port. The main research contents are as follows:(1)the circuit design of data acquisition channel. Considering the needs of high acquisition precision of the module, this part of the circuit is the core of the whole module.The main contents include how to adjust the measuring object while transferring it into a signal that is under the ADC acquisition range, the design of the peripheral circuit, and control part of ADC.(2) study the factors affecting the accuracy of data acquisition and the corresponding methods. Concentrate on the noise influence on analog channels. Calculate and analyze using the design of power supply system, the design of PCB, and ground. Find out the factors that affect the accuracy of the acquisition module, then provide possible solutions.(3) analyze the synchronization among each channel of the module, the time sequence and phase of each channel of the acquisition module, achieve synchronous sampling results of each channel. In this thesis, factors that affect the synchronization design are analyzed theoretically, and the synchronization of this module is obtained through the real-time measurement results.After completing the design, the acquisition module has been tested accordingly. The accuracy of the collected data is analyzed, problems from the whole module are analyzed,and solutions are provided. Finally, this thesis summarizes the design, and proposes suggestions for the improvement of the acquisition module.