Research Of Absolute Encoder Communication Interface Based On SSI Protocol

In recent years, with the continuous development of the field of measurement and control,absolute encoder in its communications technology is gradually optimized and improved.Most of early absolute encoder export the coded values by the way of parallel outputting,andalong with industry advances in technology and market demand, absolute encoder output hasgradually diversified, such as RS-485, PROFIBUS-DP, CAN, DeviceNet fieldbus output, etc.,as well as analog signals output SSI protocol synchronous serial output methods. At present,the German HEIDENHAIN, STEGMANN absolute encoder mainly occupy a major share ofthe market, technically in a leading position, which is equipped with means of SSIcommunication has become absolute encoder mainstream communication.However, With theSSI protocol continuously promote in the absolute encoder field,the problem of how toexpand the absolute encoder which has not the ability of SSI communication has become anurgent event.Based on the above background, in-depth analysis of the SSI protocol communicationfeatures and communication method,for parallel output absolute encoder, this article proposedsynchronous serial communication interface program based on SSI protocol,completedhardware and software design of the SSI communication interface and through experimentsproved communication hardware and software interface design is reasonable and correct. Themain contents include:First,the paper elaborated SSI protocol development status at home and abroad, theproblems and the purpose and significance of research projects in detail, Then, the absoluteencoder were introduced, and their advantages and disadvantages of various output methodswere compared with the instructions, Finally, with the absolute encoder output, the papercomprehensivly analyzed the SSI protocol communication theory and work characteristics.Second, this article discussed carefully the key technical issue how to transform theencoding value of parallel output absolute encoder into SSI data to output, and proposed SSIcommunication interface design program, on this basis, given the effective hardware andsoftware solutions. In hardware design, using STC12C5A60S2MCU, high-speed optocouplerand RS-422communication interface driver chip as the core unit,which transformed theparallel encoding value into SSI data output; in software, using the C51and assemblylanguage combined approaches to address transmission rate requirements for differentoccasions, the microcontroller,according to different frequency synchronous clock signal,securely and reliably transformed the parallel data communication interface received into theSSI data format to output.Third, according to SSI protocols,absolute encoder work characteristics and otherrequirements,the paper conducted in-depth analysis and feasibility studied the communication interface testing program,and build a communication interface SSI test platform. Finally,connectting the parallel output absolute encoder,the paper tested the designed interface deviceby experiment. Detailed analysis of the experimental results confirm the thesis put forward bySSI protocol communication interface design based on the correctness. Through detailyanalyzed the experimental results,it confirmed the correctnessthe thesis put forward SSIprotocol communication interface.