【正文】 ting circuit tests the logic level of 1wire interface, when the logic level is high, its output signal is “1”and driver of converter is shutdown。 因此 解決 了 某個(gè)傳感器或分支的損傷引起的整個(gè)總線癱瘓 的 問題。它采用 3 引腳（ GND ， DQ ， VDD ） ， TO92 封裝。數(shù)據(jù)存儲(chǔ)器保存每個(gè)的 溫度檢測(cè)點(diǎn)數(shù)據(jù)。尤其是增加散發(fā)的過度長的總線的電容會(huì)使波形的失真是不可避免的，所以發(fā)生讀 /寫錯(cuò)誤。這將大大降低溫度檢測(cè)周期，從而提高了溫度檢測(cè)速度。 傳感器溫度補(bǔ)償模塊用于對(duì)傳感器進(jìn)行誤差校準(zhǔn)。它也顯示通信狀態(tài)和的數(shù)發(fā)酵罐中的溫度數(shù)據(jù)被采樣。三個(gè)測(cè)試點(diǎn)是由上段，中段和下排。串行通信采用 RS232C 標(biāo)準(zhǔn)，數(shù)據(jù)傳 輸波特率是 9600 比特 /秒，數(shù)據(jù)格式為 8 位數(shù)據(jù)位，1 個(gè)奇偶校驗(yàn)位， 1 位停止位。此功能讓我們開始所有 的 在同一總線上的DS18B20 的溫度轉(zhuǎn)換。然而， DS18B20 的操作時(shí)段是固定的，并且許 多控制脈沖的寬度是如此之窄，只有幾微秒。 圖 1 溫度檢測(cè)系統(tǒng)的組成 溫度檢測(cè)儀的設(shè)計(jì) 溫 度檢測(cè)器的組成于圖 2 中示， AT89C51 單片機(jī)是溫度檢測(cè)器控制各種電路工作的核心。C ，其中精度為 177。 溫度檢測(cè)器提供電源通過四芯電纜為總線轉(zhuǎn)換器和 DS18B20。C ~ 176。 (2020) Trans Tech Publications, Switzerland doi:Temperature Detecting System of Beer Fermentation Based on DS18B20 FenPing Zhou, HongTao Ma, BingDong Sui， and JiaMo Sun College of Information Science amp。 when the logic level is low, its output signal is “0” and driver of converter is open. If logic level is low and its duration is more than 10ms, according to these phenomena, we can judge hardware failure occurring, temporality, the output signal is “1”, and the driver of converter will be a permanent shutdown. Thus, only failure DS18B20 is disconnected from transmission bus, the other DS18B20s can work normally. Although a bus converter can be connected to 30 DS18B20s, when shortcircuit fault occurs in one of 5 DS18B20s, the other 29 DS18B20s will stop working. If each DS18B20 can work independently and it has no effect to others when there is shortcircuit fault occurring in one of them, it is necessary for each DS18B20 equipped with a bus converter. One transmission bus can connect more than 300 converters. The Design of Management Software Software of the temperature monitoring system is developed under VISUAL BASIC , it is responsible for the work of acquiring realtime temperature, sensor temperature pensating,displaying multipoint temperature value, showing temperature variation curve, the temperature value statements and the temperature variation curve printing. Module of acquiring realtime temperature is realized through Serial munication between the industrial Computer and temperature detector. Serial munication adopts RS232C standard, the baud rate of data transfer is the 9600 bit/s, the data format is 8 data bits, 1 parity bit, and 1 stop bit. Industrial puter collects temperature value of 54 test points in 18 fermentation tanks once every 1 minute, then temperature data is saved in the puter hard disk in the format of a text file, in order to generate the temperature statements and curves of temperature change. Module of sensor temperature pensating is used to calibrate error of the sensor. It is 177。檢測(cè)溫度總線長度可達(dá)到 500 米以上。每 DS18B20 具有獨(dú)特的 64 位激光 ROM 地址碼 [ 1 ] 。 64 位程序存儲(chǔ)器保存每個(gè)溫度傳感器（ DS18B20）的激光 ROM 代碼。DALLAS 公司總線的長度建議只有 100 米， 20 個(gè) DS18B20 可以連接到它在同一時(shí)間，因此，該應(yīng)用程序是有限 制的 [2,4 ] 。 硬件故障檢測(cè)技術(shù) 當(dāng)一個(gè)電源線或系統(tǒng)中的任何 DS18B20 的數(shù)據(jù)線是短到地面時(shí)，會(huì)引起整個(gè)總線停止工作。精度 為 177。 圖 4 發(fā)酵溫度結(jié)論 4 的顯示界面 結(jié)論 通過使用數(shù)字溫度傳感器 DS18B20 的樹狀或星狀網(wǎng)絡(luò)拓?fù)浣Y(jié)構(gòu) 的 實(shí)現(xiàn)，從而簡化了溫度監(jiān)測(cè)系統(tǒng)的硬件設(shè)計(jì)，降低了系統(tǒng)的成本。你可以找到發(fā)酵罐和三個(gè)測(cè)試點(diǎn)的溫度值在發(fā)酵罐的數(shù)量從監(jiān)視器。 采 集的實(shí)時(shí)溫度模塊之間通過串行通信實(shí)現(xiàn) 和 工業(yè)電腦及溫度檢測(cè) 器的連接 。當(dāng)跳 過 ROM 命令發(fā)送到 DS18B20 ，現(xiàn)有總線上的所有 DS18B20s 可以接收它。 總線驅(qū)動(dòng)器和總線轉(zhuǎn)換器設(shè)計(jì)理論 理論上，大量 的 DS18B20 芯片 可以連接到一個(gè)總線 上 。 DS18B20 的數(shù)量可以被連接到超過 300 個(gè)。C 至 +125176。溫度傳感器和計(jì)算機(jī)之間的連接導(dǎo)線的數(shù)量將大大減少 。s I/O port to drive the transmission bus, in order to obtain further transmission distance. Watchdog and reset circuit can provide poweron reset for the microcontroller, they can also provide reset signal when program has been confused by accidentally interfering. Display is used to show the current number of fermentation tanks and temperature value of 3 sensors in fermentation tanks.