DZ202PLC溫度控制系統(tǒng)
DZ202PLC溫度控制系統(tǒng),DZ202PLC,溫度,控制系統(tǒng)
摘 要
主要介紹了一種基于的DSP水溫自動(dòng)控制系統(tǒng)的設(shè)計(jì)原理，描述了系統(tǒng)組成的各個(gè)模塊和硬件和軟件的實(shí)現(xiàn)。該系統(tǒng)通過對(duì)水溫的采樣，與預(yù)置值的比較，來控制水溫。
本系統(tǒng)采用十六位DSP（數(shù)字信號(hào)處理器）TMS320F240為主控制器，它具有運(yùn)算速度快，信號(hào)實(shí)時(shí)處理的優(yōu)點(diǎn)。另外，它片內(nèi)擴(kuò)展外設(shè)，簡化了硬件電路圖的設(shè)計(jì)，由于它面向數(shù)字控制系統(tǒng)，使得能夠運(yùn)行復(fù)雜控制算法。
在溫度采集方面，采用DS1820作為傳感器實(shí)施數(shù)據(jù)采集。采用溫度傳感器DS1820具有較高精度和重復(fù)性（重復(fù)性優(yōu)于0.1oC）良好的線性可以保證±0.1oC的測(cè)量精度，利用重復(fù)性較好的特點(diǎn)，通過非線性補(bǔ)償，可以達(dá)到±0.4oC測(cè)量精度和±0.4oC保溫精度。
控制算法采用PID算法，可以使系統(tǒng)具有較好的快速性和較小的超調(diào)。
由于本系統(tǒng)對(duì)DSP、DS1820以及PID算法的應(yīng)用，較好的滿足了設(shè)計(jì)要求，實(shí)現(xiàn)了所要求的各項(xiàng)功能。
關(guān)鍵詞：溫度控制 TMS320F240 PID算法
Design of Water Temperature Auto Control System Based on DSP
Abstract
In the aspects of this text introduced the design principle of the automatic control in water temperature in canteen in electricity system primarily. Describes the hardware and software modules were provided. That system passes to adopt the data from the electricity canteen water temperature, and compares with the refer input to control the water temperature.
This system adopts 16 bits DSP (Digital signal processor) TMS320F240 as the main device .It has the advantages of calculating speed quickly and processing signal in real time. And it has a lot of outside devices in it. This simplifies the design of the hardware circuit. Because it face to the arithmetic figure control system, it can circulate the complex control system.
DS1820 is used as the conductor of this system. It has higher accuracy and good linearity characteristic in repetition( repetition better than 0.1℃) in ± 0.1 ℃ of diagraph accuracy. It can attain the ± 0.4 ℃ measure accuracy .
The control arithmetic adopts the PID. It can make system had better of faster and smaller super adjust.
Because this system adopts DSP, DS1820 and the arithmetic of PID, it contents the design requests better.
Key Words: Temperature Control TMS320F240 PID Algorithm
Microprocessor Temperature Measuring and Control System Based on Matrix Architecture
Abstract:
This paper introduces the principle of multi-point temperature measurement based on matrix architecture and introduces the architecture of the system. A temperature measuring and control application system based on microprocessor is introduced. The factors influenced measurement and control accuracy and the methods how to improve measurement accuracy are discussed.
Key words: matrix architecture、 multi-point temperature、 microprocessor
Introduction
Microprocessor temperature measuring and control system is designed for measuring multi-point temperatures. The measurement range of temperature is –55℃ to 125℃. The temperature system can be used to measure shaft temperatures of large-scale synchronous motors or check running temperature statuses of power plants. It can be used in other situations that need to measure multi-point temperatures between –55℃ and 125℃ such as grain warehouse, zymolysis processing, etc. Comparing with other multi-temperature measurement instruments, the temperature system has high accuracy, high reliability, strong restraining interference ability, low cost, etc. Especially, because matrix architecture and two-terminal integrated circuit temperature sensors are used, the output connection lines of the temperature system are less. It is easy connecting output terminals of the temperature system to temperature points and connecting distance can be over hundreds meters. For example, if measures 64 temperature points, connection lines output from the instrument is just 8×2 = 16 output lines. But common temperature instruments need at least 2×64 = 128 lines (two terminal measurement method)
The temperature system outputs 24 channel switching control signals and 9 channel PWM control signals (period can be changed).
1 The features of AD590 and principle of matrix architecture
1.1 The features of AD590
The AD590 is a two-terminal integrated circuit temperature sensor that produces an output current proportional to absolute temperature. The device acts as a high impedance (>10MΩ) constant current regulator, passing 1μA/K for supply voltages between +4 V and +30 V. Laser trimming of chip’s thin-film resistors is used to calibrate the device to 298.21μA output at 298.2K (+25℃).
Reverse voltage added to AD590 inhibits current passing the AD590 in reverse direction. That means current passing AD590 is single direction.
The AD590 should be used in any temperature-sensing application below 150℃ in which conventional electrical temperature sensors are current employed. The inherent low cost of a monolithic integrated circuit combined with the elimination of support circuitry makes the AD590 an attractive for many temperature measurement situations. Costly transmitters, filters, lead wire compensation and linearization circuits are all unnecessary in applying the device.
The AD590 is particularly useful in remote sensing applications. The device is insensitive to voltage drops over long lines due to its high impedance current output. For instance, if the voltage from 10V dropped to 5V, it results in only a 1μA maximum current change, or 1℃ equivalent error. Any well insulated twisted pair is sufficient for operation hundreds of feet from the receiving circuitry. The output characteristics also make the AD590 easy to multiplex: the current can be switched by a logic gate output.
1.2 Principle of matrix architecture
"Matrix architecture" has m row and n column signal lines. Every line is respectively connected to a pin of single multi-channel analog multiplexers (4051). At every crossing point of row line and column line places a same model integrated circuit temperature sensor AD590 in same direction. There are totally m×n sensors. Fig 1 shows 8×8 AD590 array. Every line of column connects to power supply switched by electronic switches of multiplexer. Every time just one column line switches to supply voltage. Every line of row connects to another multiplexer. Every time just one current signal of row line switches to temperature changing and processing circuit.
Because the temperature sensor conducts current only in one direction and at anytime, just one row (i) and one column (j) are connected to system by electronic switches of multiplexers, so the only one temperature sensor (at crossing point of i row and j column) can be connected to system. The real line shows the flowing current in Fig 1. Since AD590 acts as a high impedance (>10MΩ) constant current regulator and proportion to absolute temperature, the current passing sample resistor R is only decided by the temperature in measurement point (i row, j column).
Orderly changing the row and column can sample all crossing point's temperatures orderly. The current is still decided by the temperature in relative measurement point.
2 Temperature signal amplification and processing circuit
The temperature signal amplification and processing circuit adopt a kind of typical differential amplification circuit using operational amplifier. Fig 2 shows the differential amplification circuit.
The current relation to temperature of measurement point firstly changes to voltage by resistor R. The temperature range is designed at 0℃ to 100℃ (273.2K to 373.2K). R(= R1+R2 showing in Fig 1) is 10KΩ. So the voltage added to differential amplification circuit is 2.732V to 3.732V. Offset voltage is 2.732V. Through amplifying, the voltage is amplified 2.0×2.5 = 5 times. That is The Offset voltage has high precision and low temperature drift. It is provided by reference voltage IC LM336-5.0. Because using the differential amplification circuit and reference voltage IC, the temperature drift and integrated error are very low. For the common mode interference comes from supply voltage and ground wire, it has a strong restraining ability.
3 The architecture of microprocessor temperature measuring and control system
The core part of this system is microprocessor 80C196KB. The system includes temperature sensor switching circuit, signal amplifying and processing circuits, A/D converting circuit, PWM output and switch variable output circuit, liquid crystal display circuit, communication interface and other circuits that support microprocessor working. The important part is the signal amplifying and processing circuits; it is the key to decide the accuracy of whole system. Fig 3 is the architecture of the system.
P0.0-P0.5 of 80C196KB output temperature sensor switching signals. Through the voltage transition circuit (5V to 15V), two 8-channel analog multiplexers 4051 choose only one AD590. The current of AD590 placed at i row j column is lead to sample resistor. ACH6 is used to check the voltage of power supply. When the power supply is failed or AC voltage is too low. Power down protecting program can check these statuses and protect the data. ACH7 is used to convert temperature signal VAD output from the signal amplifying and processing circuit. HSO.0-HSO.7 and P2.5 output 9 channel PWM control signals. Through simple filter, these PWM signals can be transformed to analog signals using to control heating power. HSI.0, HSI.1 and P1.0-P1.7 consist 2×8 keyboard, of which P1.0-P1.7 is set as output pins. TXD, RXD and MAX232 consist standard RS232C serial communication with supervise computer system. Vref connects to 5V reference voltage of LM336. In P3 and P4 ports, 8KB EPROM 27C64, 8KB RAM 6264, 32KB flash memory AT29C256, parallel port Intel 8255, and liquid crystal display DMC16249 are expand with other necessary control signals, of which, three ports PA, PB and PC of Intel 8255 output 8×3 = 24 switching control signals. Control logic adopts GAL16V8.It performs address decode, read and write control, etc. Because memory is flash memory, software can be update online.
4 System software
The whole program is divided into two parts. The first part is located at 2080H to 3FFFH, i.e. in EPROM 2764. When program of this part is written to EPROM, it can’t be revised later. The basic version program is write to the EPROM. The second part of program is updated program. It is located at 8080H - FFFFH, totally 32KB flash memory. Through RS232C serial communication port, Updating program can be sent to flash memory of temperature measurement system. This process is controlled by basic or previous updated program. 8000H-8079H units store system information and program version signs, of which 8000H - 8002H is version serial number. The basic version serial number is 1.01, and here writes 101(ASCII code) initially. If it is not 101, it means program was updated and system will automatically execute the update program is located in flash memory.
Interrupt vectors in EPROM are located at 2000H - 2018H. The vector addresses are fixed in EPROM and let it turn to 0000H - 0180H located in RAM respectively. Every vector occupies 0FH units stored instructions to continue process interrupts and jump to appropriate position. The instructions located at 0000H-0180H are initialized by system initialization program.
The basic version software includes system initialization part, AD590 array switching control, A/D converting, digital filter, linearization processing, scale transforming, PID control and switch variable control, display and keyboard processing, temperature self-correcting and system updating, etc.
5 The method of restraining interference
Because the length of connection lines is probably over hundreds meters and normally the lead wire is twisted-pair, the most interference comes the lead wire. Firstly, it can let terminal voltage of AD590 pins unstable. The current of AD590 will fluctuate follow the fluctuating terminal voltage. Secondly, it can invade to temperature system along the connection lines.
The mainly method is to parallel capacitors. Two terminal pins of every AD590 parallel one capacitor, showing in Fig 4. X0 to X7 pins of two multiplexers of 4051 connect one capacitor to analog ground and Vout terminal has one too. The capacitance is 0.1μF. Parallel a capacitor to AD590 let terminal voltage of AD590 very stable. So the current of AD590 don’t influence by interference anymore. All interference coming from lead wire is rejected outside the system.
But must understand that the current on lead wire and followed into the temperature system isn’t equals instantaneous current of AD590. The current followed on the sample resistor through the multiplexer is too. Just the average currents are equal at different places. It means that temperature signal sampling and amplification channel must have enough inertia to let signal more smooth. To get relative static signals, the signal switching period, A/D converter and control time interval must be enough too. Only like this, the temperature system can get real average current of AD590.
The software has strong restraining interference ability too. Normally, interference signals have orthogonality. Adopting integrated median filtering and arithmetical average filter program can effectively reject various interference signals.
In addition, pins X0-X7 of IC1 4051 respectively connect a 10KΩ resistor to analog ground. Leakage current of multi-channel analog multiplexer IC1 and reverse leakage current of AD590 can pass this resistor to the analog ground. When the array is very large, it is effective to avoid the leakage current flowing sample resistor.
6 Conclusion
Because high repeat accuracy of integrated circuit temperature sensor(0.1℃), after subsection linearizing and valuable transfer, the absolute accuracy should be less than 0.1℃.
The application system uses 10 bit A/D converter (embeded in 80C196KB) and adopts necessary effective restraining interference methods. In 0℃ to 100℃ of temperature measurement range, the temperature system has been tested thoroughly and has been applied in industrial measurement. It has a high performance and measurement accuracy. The maximum measurement error is less than 0.2℃. The maximum control error is less than 0.5℃.
原文網(wǎng)址：http://websun.51.net/edu/lw64WD.htm
6
基于矩陣建筑機(jī)構(gòu)的微處理器溫度測(cè)定和控制系統(tǒng)
文章摘要:
本文介紹了基于矩陣建筑學(xué)多點(diǎn)溫度測(cè)量的原理和系統(tǒng)建筑學(xué)。介紹了溫度測(cè)量和以微處理器為基礎(chǔ)的控制系統(tǒng)。討論了影響測(cè)量和控制準(zhǔn)確性的因素，以及如何改進(jìn)測(cè)量的準(zhǔn)確性。
關(guān)鍵字: 矩陣建筑學(xué)、多點(diǎn)溫度、微處理器
說明
微處理器溫度測(cè)量和控制系統(tǒng)設(shè)計(jì)用來測(cè)定多點(diǎn)溫度。 溫度的測(cè)量范圍是 -55℃到125℃。 溫度系統(tǒng)能被用測(cè)量大規(guī)模的同時(shí)能測(cè)量發(fā)動(dòng)機(jī)的溫度或檢測(cè)電力工廠溫度。它能也在其他的情形中用于在 -55℃和+125℃之間的場(chǎng)所，例如：糧食倉庫、發(fā)酵處理廠等。與其他的多溫度測(cè)量工具想比較,該溫度系統(tǒng)有高準(zhǔn)確性,高可信度,強(qiáng)大的抗干擾的能力,尤其是其較低費(fèi)用。由于矩陣建筑學(xué)和兩個(gè)管角集成電路溫度感應(yīng)器,所以此溫度系統(tǒng)的輸出連接線是比較少的。它很容易把連結(jié)溫度系統(tǒng)的輸出終端連接到到溫度測(cè)量點(diǎn)而且連接距離達(dá)到數(shù)百公尺。舉例來說，如果測(cè)量64個(gè)溫度點(diǎn),連接排成一行來自工具的輸出陣好是的 8×2=16條輸出線。但是通常的溫度工具需要至少 2×64=128條 (二個(gè)接線端測(cè)量方法)
此溫度系統(tǒng)輸出 24個(gè)條轉(zhuǎn)變控制信號(hào)和9條PWM的控制作信號(hào)。(周期性變化)
1 矩陣建筑學(xué)體系和AD590原理及特征
1.1 AD590 的特征
AD590 是一兩個(gè)輸出端的集成電路溫度傳感器，輸出電壓很絕對(duì)溫度成比例。該設(shè)備相當(dāng)一個(gè)高阻抗的電流調(diào)整器(>10MΩ)。供電電壓在 +4 V 和 +30 V之間.每當(dāng)溫度產(chǎn)生變化的時(shí)候如：變化298.2K相應(yīng)的輸出為298.21 μA。(相當(dāng)于25 ℃)
當(dāng)反向電壓加到AD590上時(shí)，出現(xiàn)電流不通的現(xiàn)象。這就意味著AD590是單一方向的傳感器。
AD590能在常規(guī)溫度在150 ℃的在任何的測(cè)溫度的系統(tǒng)中使用。 AD590集成電路的固有的較低費(fèi)用，和其很好的性能，使其在許多有溫度測(cè)量場(chǎng)合深受人們喜愛，有許多的昂貴發(fā)射器，過濾器，昂貴的電線線路在許多應(yīng)用裝置方面是不必要應(yīng)用的。
在距離較遠(yuǎn)的測(cè)量溫度中AD590的效果特別地好。 由于它的高阻抗的輸出，使設(shè)備對(duì)由于長距離傳輸而沒有電壓下降的感覺。 舉例來說，如果10V的電壓降低到5V,它最大只能造成1μA變化, 或者只相當(dāng)于1℃的誤差變化。任何絕緣好的雙絞線從數(shù)百米之外接受控制都是可以的。其輸出特性也使AD590容易有多元性: 電流容易被轉(zhuǎn)變成邏輯門電路輸出。
1.2 矩陣建筑機(jī)構(gòu)的原理
"矩陣建筑機(jī)構(gòu)" 有m行和n列信號(hào)線。每條線分別地被連接到單一多項(xiàng)類似的多路器上(4051)。在每個(gè)橫行和豎行的的交叉口，放置相同方向同樣的集成電路溫度傳感器AD590。這樣總共有m×n個(gè)傳感器。每一面有8×8個(gè)AD590排列。豎行的每條線連接使被多個(gè)傳感器器的電子開關(guān)轉(zhuǎn)變的補(bǔ)給有力量。每一次正直的專欄線轉(zhuǎn)變供應(yīng)電壓。排的每條線連接到另外的一個(gè)多路器。只是每一排現(xiàn)在信號(hào)對(duì)溫度變更而且處理線路轉(zhuǎn)變。
因?yàn)闇囟葌鞲衅髟谝粋€(gè)方向中的導(dǎo)通是唯一和隨時(shí)的，橫排(i)和豎排(j)被連接到多路器的電子開關(guān)的系統(tǒng),多以只有一個(gè)溫度傳感器(在 I橫行和j豎行) 能被連接到系統(tǒng)。 真正的線在Fig1中體現(xiàn)流動(dòng)方向。既然AD590相當(dāng)于作用一個(gè)高阻抗 (>10MΩ) 其變化隨絕對(duì)溫度的變化而變化，當(dāng)前流過電阻R的電流只被測(cè)量點(diǎn)的溫度決定 (i 橫排和j豎排) 。
橫排和豎排有秩序的的變化能夠體現(xiàn)所有點(diǎn)溫度有秩序的的變化。電流仍然由被測(cè)量點(diǎn)的溫度決定。
2 溫度信號(hào)的放大和處理線路
溫度信號(hào)的放大的和處理線路采用一種典型的為分放大線路。Fig2說明了這種微分放大線路。
當(dāng)前的電流通過測(cè)量點(diǎn)的檢測(cè)溫度換成溫度范圍為0℃到100℃，通過電阻R轉(zhuǎn)化為電壓，（對(duì) 373.2K到273.2K）。R(=R1+ R2)是10KΩ。如此電壓把微分放大電路的電壓從2.732V到3.732V。偏移電壓是2.732V。經(jīng)過擴(kuò)大，電壓被擴(kuò)大為原來的2.0×2.5=5倍。
偏移電壓有高精密和較少的溫度漂移。它是由參考電壓集成電路LM336-5.0提供。因?yàn)槭褂梦⒎址糯箅娐泛蛥⒖茧妷杭呻娐?溫度漂移和整合的錯(cuò)誤非常低。由于共態(tài)干擾來自電壓和地線,他有較強(qiáng)的抗干擾能力。
3 微處理器溫度測(cè)定和控制系統(tǒng)的建筑學(xué)
這個(gè)系統(tǒng)的核心部份是微處理器80C196KB系統(tǒng)包括溫度感應(yīng)器轉(zhuǎn)變線路，信號(hào)放大和處理線路，A/D 轉(zhuǎn)換線路，PWM 輸出和開關(guān)變數(shù)輸出線路，液晶顯示電路，通信接口和支持微處理器的其他線路。重要的部份是信號(hào)放大和處理線路；它是決定整個(gè)的系統(tǒng)準(zhǔn)確性的關(guān)鍵。Fig3是系統(tǒng)的建筑學(xué)。
80C196KB的P0.0-P0.5是溫度傳感信號(hào)的轉(zhuǎn)化口。經(jīng)過電壓轉(zhuǎn)變線路(對(duì)5V到15V)，二個(gè)8個(gè)通道的多路器4051只選擇一個(gè)AD590。放置在i排j列的AD590所檢測(cè)到的電流通過電阻轉(zhuǎn)化成電壓。ACH6用來檢測(cè)低壓電源。當(dāng)電力驅(qū)動(dòng)的電壓不足的時(shí)候否說明AC的電壓太低。電源下的保護(hù)程序檢測(cè)到這些情況和保護(hù)這些數(shù)據(jù)。ACH7用來轉(zhuǎn)換來自信號(hào)放大和處理線路的溫度信號(hào)VAD輸出。HSO.0-HSO.7和P2.5輸出9路PWM的控制信號(hào)。通過簡單的過濾器,這些 PWM信號(hào)能夠被轉(zhuǎn)換成模擬的電信號(hào)從而控制熱力開關(guān)。HSI.0、HSI.1和P1.0- P1.7組成的2×8的鍵盤,P1.0- P1.7是放置輸出點(diǎn)。TXD、RXD和MAX232組成標(biāo)準(zhǔn)的RS232C串行通信連接監(jiān)控計(jì)算機(jī)系統(tǒng)。Vref連接到LM336的5V電壓。在P3和P4口，8KB EPROM、27C64、8KB RAM 6264、32KB閃存，在AT29C256中，放置Intel8255和DMC16249的的必要控制信號(hào)放大控制液晶顯示,其中3個(gè)PA口,Intel8255輸出8×3=24轉(zhuǎn)換控制信號(hào)、PB和PC控制信號(hào)?？刂七壿嫴捎肎AL16V8。他能通過快速閃存進(jìn)行讀和寫的控制,軟件可在線更新。
4 系統(tǒng)軟件
整個(gè)設(shè)計(jì)被分為兩個(gè)部份。第一部份從3FFFH到2080H,在EPROM 2764中，也就是，當(dāng)這個(gè)部份的程序被寫到EPROM之后就不能被更改?；镜某绦蚴潜粚懙紼PROM中的。第二個(gè)部份的程序被更新。它位於8080H- FFFFH, 32KB閃存。經(jīng)過RS232C串行通訊口,更新的程序能被輸送到溫度測(cè)量系統(tǒng)的內(nèi)存中。這個(gè)程序被控制被基本的或早先的更新程序。8000H-8079H是系統(tǒng)數(shù)據(jù)儲(chǔ)存單元而且顯示版本,其中8000H- 8002H是版本序號(hào)。基本的版本序號(hào)是 1.01，而且這里最初寫101(美國信息交換標(biāo)準(zhǔn)代碼密碼)。如果它是不101,就意味著程序被更新了，且系統(tǒng)將會(huì)自動(dòng)地運(yùn)行更新程序于閃存中。
在EPROM中斷位于2000H- 2018H。在EPROM被修改并且讓它指向0000H-0180H在隨機(jī)存取儲(chǔ)存器中位于0180H。每個(gè)矢量占用0FH個(gè)單元。儲(chǔ)存了指令繼續(xù)對(duì)適當(dāng)?shù)奈恢贸绦蛑袛嗪吞S。位于0000H-0180H的指令被系統(tǒng)初始化。
基本的版本軟件包括系統(tǒng)初始化部份，AD590排和列轉(zhuǎn)變控制、A/D轉(zhuǎn)換、數(shù)字濾波器，線性化處理、標(biāo)度轉(zhuǎn)換、PID控制和開關(guān)量的控制，液晶顯示和鍵盤處理，溫度自動(dòng)調(diào)整和系統(tǒng)更新等
5 抑制干擾的方法
由于連接線的長度超過數(shù)百公尺，而且通常的導(dǎo)線是雙絞線,大多數(shù)的干擾來自導(dǎo)線。第一，它能使AD590的輸入電壓不穩(wěn)定。AD590的電流將會(huì)跟隨終端電壓變動(dòng)。第二，它能沿著導(dǎo)線侵入到溫度系統(tǒng)中。
那主要地方法是用平行電容器。每個(gè)AD590在輸入端平行一個(gè)電容器在.對(duì)二個(gè)多路器的 X7接頭和X0 4051連結(jié)一個(gè)電容器到地面各有一個(gè)。電容量是對(duì) AD590 的0.1μF.并聯(lián)一個(gè)電容器讓AD590的終端電壓非常穩(wěn)定。如此AD590的電流不再受到干擾。所有的來自系統(tǒng)外面的干擾被拒絕。
但是一定的環(huán)境之下電流流過電線進(jìn)入溫度系統(tǒng)之內(nèi)不是跟隨AD590的。電流流過電阻上經(jīng)過多路器。平均電流在不同的地方是相等的。它意味著溫度的取樣和信號(hào)的放大必須在一定且有充足的量從而使信號(hào)更平滑。為了要拿到相對(duì)穩(wěn)定的信號(hào),信號(hào)轉(zhuǎn)變周期，A/D轉(zhuǎn)換器和控制時(shí)間間隔一定要足夠，只有這樣,溫度系統(tǒng)才能得到AD590檢測(cè)到的真正的平均電流。
軟件也有較強(qiáng)抗干擾的能力。通常干擾信號(hào)都有正交性。采集中值過濾和算術(shù)平均過濾器的方法能有效地拒絕各種干擾信號(hào)。
除此之外，IC14051的X0-X7接頭，分別連結(jié)10KΩ的電阻器到地面。AD590的多路相反漏電流能流過這個(gè)電阻。阿當(dāng)輸入量非常大的時(shí)候,它能有效避免漏電流。
6 總結(jié)
因?yàn)榇罅康闹貜?fù)測(cè)量，集成電路溫度傳感器的精度(0.1℃)的準(zhǔn)確性應(yīng)該是少于0.1℃。
此系統(tǒng)使用了10個(gè)A/D轉(zhuǎn)換器(在80C196KB中使插入的)，而且采用了必要而有效抗干擾的方法。在0℃到100℃的溫度測(cè)量值中,此溫度系統(tǒng)能在工業(yè)的測(cè)量中被大量應(yīng)用。它有較高的精度和測(cè)量準(zhǔn)確性。最大的測(cè)量誤差少于0.2℃。最大的控制誤差少于0.5℃。
4
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