CN2695936Y

CN2695936Y - Intelligent thermometer calibrater

Info

Publication number: CN2695936Y
Application number: CN 200420031813
Authority: CN
Inventors: 孙立红
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-05-31
Filing date: 2004-05-31
Publication date: 2005-04-27
Anticipated expiration: 2014-05-31

Abstract

An intelligent thermometer calibrater is multiple function intelligent instrument equipped with an input/output interface circuit and serves an SCM as its kernel. The utility model adopts a membrane keyboard and an LED display to provide the man-machine dialog function. The users can transmit the various data to be measured and displayed into the instrument by the keyboard, and the instrument proceeds input or output operation output operation according to the users' requirements and displays the results on the display. The utility model is suitable for the important industrial fields such as petroleum, chemical industry, electric power, metallurgy, etc. The utility model can adjust, calibrate and test the temperature sensor, the controlling system and measuring system in the temperature measuring and controlling system. The utility model overcomes the deficits of low accuracy and poor reliability of the checking work caused by various instruments to check, and realizes a tractor serves a plurality of purposes with small size, convenient carrying and high anti-interference capability. The accuracy of the utility model can reach 0.01%, and the utility model is especially suitable to check the sensor and the measuring and controlling system on site.

Description

Intelligent temperature instrument check instrument

Technical field: the utility model relates to a kind of multifunctional intellectual thermometric instrument tester, be applicable to essential industry fields such as oil, chemical industry, electric power, metallurgy, can adjust, calibrate and test the temperature sensor in the measuring and controlling temp system, control system and measuring system.

Background technology: at present domesticly major part is adjusted, calibrates and tested to temperature sensor and temperature control system all use standard resistance box to make resistance signal source, millivolt signal is provided or uses other standard signal source with electron potentiometer.Cause the precision of verification work and reliability to be affected owing to use multiple instrument to carry out verification, especially carrying out verification in the working site has many inconveniences especially.

Summary of the invention: the purpose of this utility model is at above-mentioned the deficiencies in the prior art, and a kind of intelligent temperature instrument check instrument that can adjust, proofread and correct, overhaul, safeguard temperature sensor, control system and measuring system in the measuring and controlling temp system of undertaking important TT﹠C task in essential industry fields such as oil, chemical industry, electric power, metallurgy is provided.It overcomes carries out verification by multiple instrument and causes deficiencies such as the low and poor reliability of the precision of verification work, has realized a tractor serves several purposes, and especially making to test in the working site becomes possibility.For achieving the above object, the utility model adopts following technical proposals: intelligent temperature instrument check instrument is to be the intelligence instrument of the defeated people's output interface circuit of core configuration with the single-chip microcomputer.Adopt membrane keyboard and light-emitting diode display that the man-machine conversation function is provided.Every data that the user can measure and show are input in the instrument by keyboard, and instrument inputs or outputs operation according to user's requirement, and its result is shown on display.For example, the customer requirements output signal, as long as key in the signal value (this signal value can be certain magnitude of voltage or certain temperature value) that will export, display will show signal value in correspondence with each other, and output signal.Measurement to input signal is that measured object is inserted input terminal, realizes measuring by function key, and its measured value is shown on display.Because the millivolt value and the temperature value of five kinds of thermopairs are nonlinear relationships, its corresponding relation reflects with form.In hardware circuit design, program storage is extended to 64K.With the storage of 4 27C256 EPROM as stored programme and data form, 8155 as resistor network selection output interface, 8155 operations needing to be obtained the resistance value of output by software programming.Owing to need external output dc voltage, current signal, and require high-precision signal output, thus the D/A digital to analog converter of 16 of AD669 adopted, as the output of 0-200mV DC, 0-10VDC; Adopt the output of AD421 16 bit serial input 4-20mA current loop.

The utility model is applicable to sensor and TT﹠C system verification, test, adjustment, is the multifunctional comprehensive intelligence instrument.In essential industry fields such as oil, chemical industry, electric power, metallurgy, can be used for the verification of sensor and TT﹠C system.The instrument check instrument has overcome multiple instrument to carry out verification and causes deficiencies such as the low and poor reliability of the precision of verification work, has realized a tractor serves several purposes, and its volume is little, easy to carry, antijamming capability is strong, and precision can reach 0.01%.Be particularly useful for the verification of spot sensor and TT﹠C system.

Description of drawings:

Fig. 1 is keyboard-display circuit figure of the present utility model (man-machine interface)

Fig. 2 is the utility model D/A converting circuit figure (backward channel)

Fig. 3 is the utility model analog to digital conversion circuit figure (forward path)

Embodiment:

With reference to Fig. 1, because this confidential input of asking is more, consider the accuracy requirement of assurance system, need to adopt 12 LED data presentation, form keyboard by ten key and function key, select 8279 for use as keyboard and display interface device.The ALE pin of single-chip microcomputer 89C52 links to each other as clock signal with the CLK of programmable keyboard, display interface device circuit 8279; P2.7 is connected with 8279 CS, and 8279 is selected during CS=0; Two WR, RD are corresponding to link to each other; 8279 IRQ is through the INT of not circuit and 89C52 ₁Connect as interrupting the application signal, high level is effective; P0 mouth and 8279 the corresponding connection of data port DB0-DB7, transferring command and data between single-chip microcomputer and 8279, the P0 mouth is given 8279 A through eight D-latch 74LS373 output single-wire signal ₀, A ₀=0 o'clock Data transmission between single-chip microcomputer and 8279, otherwise be order.Programmable keyboard, display interface device circuit 8279 delivery outlet SL0-SL3 through 4-16 line 74LS154 code translator output scanning signal as the keyboard column scan signal, obtain capable signal by RL0, RL1 and can obtain key code, sweep signal through 75452 not gates to common cathode charactron bit scan, OUTA0-OUTA3 by 8279, OUTB0-OUTB3 output shows signal data are given hex buffer 74LS07 section code selection as charactron, finish dynamic scan.

With reference to Fig. 2, this tester requires the dc voltage and current signal accuracy of input and output higher, so characteristics such as the AD669 16 figure place weighted-voltage D/A converters of selecting for use U.S. AD company to produce, this digital to analog converter have high performance price ratio, be widely used are also simpler with the interface circuit of 89C52.The 4-20mA current output circuit similarly, usefulness be the digital to analog converter of the U.S. AD company AD421 16 bit serial input 4-20mA electric current loop output of producing, when input zero during to full scale, LOOP RTN pin can obtain corresponding 4-20mA electric current.The P1.0-P1.2 of single-chip microcomputer 89C52 is connected with input end A, B, the C of 74LS138 through 3-8 line code translator 74LS138 output pin Y5 and provides digital to analog converter AD669 chip selection signal; The P0 mouth of 89C52 provides 16 input data of AD669 through LS373 and the timesharing of P0 mouth, provides voltage output by AD669 then, and the P0 mouth of concrete method of attachment: 89C52 is connected with the DB8-DB15 of AD669 through LS373, and the P0 mouth is connected with the DB0-DB7 of AD669.

With reference to Fig. 3, this tester requires to have the measurement function to input signal or output signal, can satisfy direct current 0-200mV exactly comparatively speaking, the measurement of the DC voltage of 0-10V scope, the measurement of 4-20mA direct current scope, and the measurement of 100-320 Ω resistance.Measurement to above-mentioned analog quantity is realized by Fig. 3 A/D conversion interface circuit.The V-I mensuration has been adopted in the measurement of resistance R x, to obtain higher measuring accuracy.

Simulating signal inputs to MAX111, and MAX111 is single supply, low-power consumption, 14 bit serial analog to digital converters.The chip selection signal of MAX111 is connected with input end A, B, the C of 74LS138 by the P1.0-P1.2 of 89C52, and Y6 provides through 3-8 line code translator 74LS138 output pin, and Y6 is connected with the CS of MAX111, and the CS low level is effective; The BUSY of MAX111 is connected with the RD of 89C52, and DOL Data Output Line DOUT is connected with the RXD of 89C52, and serial input data is given single-chip microcomputer.

The software of the present utility model structurized method for designing.Because the instrument precision prescribed is higher, the interface circuit that hardware circuit design is selected for use is more, in order to improve reliability and to satisfy accuracy requirement, has adopted fault-tolerant design technique.Requiring speed aspect data acquisition and the processing is not very high, for reducing the spending of hardware circuit, hardware circuit is simplified as far as possible, except the necessary hardware interference protection measure, has made full use of the advantage of Software Anti-interference.

1, keyboard and demonstration

In order to save the time of CPU, adopted the software design approach of interrupt mode.At hardware circuit design corresponding initialization subroutine, display upgrades subroutine, key input interrupt service subroutine, key is handled subroutine.Handle the fault-tolerant design technique that has adopted the parameter input in the subroutine at key, make and the transmission that interactive information can be correct reduce maloperation.

2, forward path A/D (modulus) conversion

Comprise according to the setting of the control word of the MAX111 of hardware circuit requirement with the configuration of determining A/D converter and the control of working method, comprise control change time, clock division than, select input channel, the gain calibration mode be set, zero offset mode etc.Scheduling and instruction according to watchdog routine are finished different physical parameters by the control of analog quantity to the transfer process of digital quantity.Owing to need the content of parameter and the range discrimination of measurement bigger, will come the different parameter of differentiating and processing according to monitored instruction.In order to improve the precision of instrument, adopt the digital zero setting technology to reduce to measure additive error.

3, backward channel D/A (digital-to-analogue) conversion

The output of dc current signal and d. c. voltage signal is arranged in backward channel, selected two kinds of D/A converter spares in the hardware circuit for use, the D/A switching software carries out the transmission of initialization, translation data to D/A converter.

4, monitoring management

Watchdog routine is responsible for coordinating each subroutine and is realized various functions.According to the parameter of keyboard input and finishing of task, the relevant subroutine of dispatch control is finished related work, implements a kind of closed-loop control system.Correlated error is carried out dynamic calibration, obtaining the physical quantity output of degree of precision, give accurate quantitative expression the accuracy of detected physical quantity.

5, data processing

Because the temperature value and the magnitude of voltage of thermopair are nonlinear relationships, can't obtain mathematical model, can only set up data form and reflect corresponding relation between them, can only obtain corresponding data relationship with the method for tabling look-up.Because form is very long, look into very time-consuming, so form is divided into many zonules, earlier with data through calculating zone with definite its place, then, in this zone, table look-up according to the order of sequence, improved work efficiency.

To selecting of output resistance, be by the calculating selected method of tabling look-up, promptly according to the resistance value that should export, drive relay assembly, select resistance, and then calculate error correction through measuring actual output resistance and given resistance value compared, and again output resistance is compensated, to export to obtain accurately resistance. the output for DC voltage and dc current signal also is according to said method to carry out.

Its major function:

1, measures various thermal resistance signals, show resistance value or corresponding temperature value simultaneously;

2, measure the millivolt signal of five kinds of thermopair calibration number, and convert corresponding temperature value to, have the cold junction compensation function;

3, output and measuring voltage, current signal;

4, output passive resistance signal, the while can show the temperature value of resistance value correspondence.

The major technology index is:

One, output signal

1, the millivolt and the temperature signal of thermopair

S calibration 0-18.693mv, 0-1768 ℃;

B calibration 0-13.820mv, 0-1820 ℃;

K calibration 0-54.886mv, 0-1372 ℃;

T calibration 0-20.872mv, 0-400 ℃;

E calibration 0-76.373mv, 0-1000 ℃.

2, thermal resistance resistance and temperature signal

Platinum resistance 100-317.06Q, 0-600 ℃;

Copper resistance 100-164.27Q, 0-150 ℃;

3, voltage and current signal source

0-200mV?DC

0-10V?DC

4-20mA?DC

Two, can measure input signal, its measurement range and precision are identical with output signal.

Three, precision＜0.01%.

Four, working temperature 0-40 ℃.

Five, supply voltage ± 10%.

Claims

1, a kind of intelligent temperature instrument check instrument, it is characterized in that: it is to be the core configuration input/output interface circuit with the single-chip microcomputer, adopt membrane keyboard and light-emitting diode display that man-machine conversation is provided, program storage is extended to 64K, with the storage of 4 27C256 EPROM as stored programme and data form, 8155 as resistor network selection output interface, adopt the D/A digital to analog converter of 16 of AD669, as the output of 0-200mV DC, 0-10V DC, adopt the output of AD421 16 bit serial input 4-20mA current loop.

2, intelligent temperature instrument check instrument according to claim 1, it is characterized in that: adopt 12 LED data presentation, form keyboard by ten key and function key, select 8279 for use as keyboard and display interface device, the ALE pin of single-chip microcomputer 89C52 links to each other with the CLK of programmable keyboard, display interface device circuit 8279; P2.7 is connected with 8279 CS, and two WR, RD are corresponding to link to each other; 8279 IRQ is through the INT of not circuit and 89C52 ₁Connect, P0 mouth and 8279 the corresponding connection of data port DB0-DB7, the P0 mouth is exported single-wire signal to 8279 A through eight D-latch 74LS373 ₀Programmable keyboard, display interface device circuit 8279 delivery outlet SL0-SL3 are through 4-16 line 74LS154 code translator output keyboard column scan signal, by RL0, RL1 obtains key code, sweep signal through 75452 not gates to common cathode charactron bit scan, 8279 OUTA0-OUTA3, OUTB0-OUTB3 is connected the section code selection that provides charactron with hex buffer 74LS07, AD669 16 figure place weighted-voltage D/A converters are selected in voltage output for use, the 4-20mA current output circuit is selected the digital to analog converter of AD421 16 bit serial input 4-20mA electric current loop output for use, the input end A of the P1.0-P1.2 of single-chip microcomputer 89C52 and 74LS138, B, C connects, and 3-8 line code translator 74LS138 output pin Y5 is connected with the CS of digital to analog converter AD669; The P0 mouth of 89C52 is connected with the DB8-DB15 of AD669 through LS373, the P0 mouth is connected with the DB0-DB7 of AD669, this tester requires direct current 0-200mV, the measurement of the DC voltage of 0-10V scope, analog to digital converter MAX111 is adopted in the measurement of 4-20mA direct current scope, and the measurement of 100-320 Ω resistance, the P1.0-P1.2 of 89C52 is connected with input end A, B, the C of 74LS138, and 3-8 line code translator 74LS138 output pin Y6 is connected with the CS of MAX111; The BUSY of MAX111 is connected with the RD of 89C52, and DOL Data Output Line DOUT is connected with the RXD of 89C52.