工業自動化數據采集的無線結構

　　本文討論了用于無線分發的數據捕獲的不同選項，以支持工業自動化應用程序。它著眼于數據捕獲的不同層次的集成，以及用于連接傳感器和其他設備的不同無線技術的接口。它涵蓋了芯片mrf49xa收發器在ISM頻帶低于900赫茲和Silicon Labs em351 2.4 GHz的應用。

　　片上系統（SOC）設備在工業自動化無線數據采集設計中越來越流行。收發信機需要一個微控制器來處理協議棧和傳入的數據打包。將控制器與無線電前端結合起來，減少了設計的足跡、成本和復雜性。頻帶和協議的選擇取決于數據帶寬的要求，而這又取決于所使用的傳感器結構和數據采集系統。

　　然而，對于較低的數據速率、低成本的較低頻段的應用，仍然有一個單獨的收發器，可以很容易地集成到低成本控制器，與數據轉換器和傳感器子系統的要求相匹配。

　　Wireless systems are used to link sensors around the factory floor to a central monitoring point. These wireless sensor networks （WSN） provide vital data， from the status of a process to the health of a piece of machinery. This helps optimize the performance of the industrial process and flag problems with equipment to allow for replacement before it fails， avoiding costly down time.

　　Integrated system-on-chip devices such as the Silicon Labs EM351 use the I2C interface， which is a common output from an analog-to-digital converter （ADC）。 This， along with the SPI interface， can dramatically simplify the design of the node， providing a simple two or four wire interface to the data converter. The choice of converter will be determined by the output protocol to ensure they are well matched in performance – from a lower data rate 868 MHz ISM band with an 8-bit controller to a 2.4 GHz ZigBee node with a 32-bit processor.