一種實用的微機自動配料秤系統(tǒng):介紹一種由單片機構(gòu)成的配料秤。敘述了秤的傳感器、變送器、信號的變換、硬件原理、軟件流程以及和DCS 系統(tǒng)構(gòu)成的單回路調(diào)節(jié)系統(tǒng),此系統(tǒng)可廣泛地應(yīng)用于各行業(yè)的配料控制中。關(guān)鍵詞:配料秤 單片機 單回路調(diào)節(jié)系統(tǒng) DCS 系統(tǒng)
Abstract :A proportioning weigher based on single chip computer is introduced. Sensors , transmitters , Signal converting , principle of hardware ,software flowchart of proportioning weigher and single loop control system composed with DCS system are emphasized ,this system can be used in proportioning control of various trades extensively.Key Words :Proportioning Weigher ,Single Chip Computer ,Single Loop Control System ,Distributed Control System
標簽：
微機
自動
配料秤
上傳時間：
2013-10-12
上傳用戶：zwei41
All inputs of the C16x family have Schmitt-Trigger input characteristics. These Schmitt-Triggers are intended to always provide proper internal low and high levels, even if anundefined voltage level (between TTL-VIL and TTL-VIH) is externally applied to the pin.The hysteresis of these inputs, however, is very small, and can not be properly used in anapplication to suppress Signal noise, and to shape slow rising/falling input transitions.Thus, it must be taken care that rising/falling input Signals pass the undefined area of theTTL-specification between VIL and VIH with a sufficient rise/fall time, as generally usualand specified for TTL components (e.g. 74LS series: gates 1V/us, clock inputs 20V/us).The effect of the implemented Schmitt-Trigger is that even if the input Signal remains inthe undefined area, well defined low/high levels are generated internally. Note that allinput Signals are evaluated at specific sample points (depending on the input and theperipheral function connected to it), at that Signal transitions are detected if twoconsecutive samples show different levels. Thus, only the current level of an input Signalat these sample points is relevant, that means, the necessary rise/fall times of the inputSignal is only dependant on the sample rate, that is the distance in time between twoconsecutive evaluation time points. If an input Signal, for instance, is sampled throughsoftware every 10us, it is irrelevant, which input level would be seen between thesamples. Thus, it would be allowable for the Signal to take 10us to pass through theundefined area. Due to the sample rate of 10us, it is assured that only one sample canoccur while the Signal is within the undefined area, and no incorrect transition will bedetected. For inputs which are connected to a peripheral function, e.g. capture inputs, thesample rate is determined by the clock cycle of the peripheral unit. In the case of theCAPCOM unit this means a sample rate of 400ns @ 20MHz CPU clock. This requiresinput Signals to pass through the undefined area within these 400ns in order to avoidmultiple capture events.
標簽：
C16x
微控制器
輸入信號
時序圖
上傳時間：
2014-04-02
上傳用戶：han_zh
