RMT Ltd RMT Ltd Joint Stock Company Optical Unit DX6106 Series User Guide 2002 Rev. 1.10 DX6106 RMT Ltd Edition April 2002 Copyright All right reserved. Reproduction in any manner, in whole or in part is straightly prohibited without written permission of RMT Ltd The information contained in this document is subject to change without notice. Limited Warranty RMT Ltd warrants that DX6106 Optical Unit, if properly used and installed, will be free from defects in material and workmanship and will substantially conform to RMT’s publicly available specification for a period of one (1) year after date of DX6106 Optical Unit was purchased. If the DX6106 Optical Unit which is the subject of this Limited Warranty fails during the warranty period for the reasons covered by this Limited Warranty, RMT, at this option, will : REPAIR the DX6106 Optical Unit; OR REPLACE the DX6106 Optical Unit with another DX6106 Optical Unit. Trademark Acknowledgments All trademarks are the property of their respective owners. RMT Ltd. 53 Leninskij prosp. Moscow 119991 Russia phone: 095-132-6817 fax: 095-132-5870 e-mail: [email protected] http://www.rmtltd.ru REV. 1.10/2002 RMT Ltd DX6106 Contents 1. Introduction 2. Theory of Operation Principles of Operation Design Features Operation Overview 3. Construction of Optical Unit Gas Sampling Cell Optocomponent 6102 Optocomponent Mating Module Preamplifier Thermoelectric Cooler Thermistor Light Emitters EEPROM EEPROM Data Format 4. Installation Tips 5. Calibration Preparation Zero Adjustments Re-Calibration 6. Maintenance Optics Cleaning 7. Standard Kit 8. Specifications 9. Ordering Guide Contents 1-1 2-1 2-4 2-5 3-1 3-2 3-5 3-7 3-10 3-13 3-19 3-24 3-27 3-30 4-1 5-1 5-1 5-3 5-4 6-1 7-1 8-1 9-1 C-1 DX6106 C-2 RMT Ltd REV. 1.10/2002 RMT Ltd DX6106 1. Introduction The company RMT Ltd introduces new DX6106 series of Optical Units for gas measurement systems. The principle of operation is based on selective absorption of IR radiation by gas molecules. The differential double frequency optical scheme provides high accuracy in wide ranges of humidity and temperature due to the internal thermostabilization. New type of middle infrared combined optocomponent with built-in thermoelectric cooling is used. There are several models suitable for the following gases : CO2, CH4, CnHm, water vapor. Advantages high selectivity and stability wide range of measured concentrations fast response no direct contact of sensitive element with measured gas the long service life Features no moving parts minimum dimensions and light weight low power consumption Introduction 1-1 DX6106 1-2 RMT Ltd REV. 1.10/2002 RMT Ltd DX6106 2. Theory of Operation Principles of Operation The NDIR (Non-Dispersive Infra-Red Spectroscopy) measurement method is implemented in the DX6106 Optical Unit. The device provides gases concentration measurement based on the classical double channel optical scheme (Fig. 2.1). One of the beams (measuring channel) has the wavelength which is tuned to the optical absorption line of the measured gas. The other beam (reference channel) has the wavelength which is out of the adsorption band of the measured gas. Intensity Intensity Intensities of two light beams that passed through the measured gas sampling cell are compared. l1 l2 Wavelength Photoresistor Gas Flow Light Emitters l1 l2 Wavelength Fig. 2.1. The principle of gas concentration Theory of Operation 2-1 RMT Ltd DX6106 According to the Beer-Bouguer-Lambert law, light absorption in a gas volume is proportional to the absorbing gas concentration: where I = I0 × e -a L X I0 – intensity of light before pass through the gas I volume; – intensities of light after pass through the gas volume; Relative response a – absorption coefficient of the gas at the chosen light wavelength; L – optical pass length; X – gas concentration. At a fixed L and 1.0 known Photodetector absorption a it is possible to find gas concen0.5 Reference Measuring tration using channel channel measured intensity of light (measuring 0 channel) that 2.0 3.0 4.0 Wavelength, µm passed from Light Emitter to Fig. 2.2. Spectral bands of light emitters for methane analyzer Photodetector. 2-2 REV. 1.10/2002 RMT Ltd Emission band 1.0 Reference channel Measuring channel 0.5 0 2.0 Relative absorption Reference channel is used for indirect measuring of the initial intensity of light, and allows to eliminate actual measurements conditions (total transparency of gas volume, optics imperfection and so on). DX6106 3.0 4.0 3.0 4.0 1.0 Methane 0.5 0 2.0 Wavelength, µm In Fig. 2.2 the Fig. 2.3. Spectral bands of light emitters and methane example of spectral bands of light emitters for methane analyzer is shown. The detailed description of the optocomponent is given in Chapter 3. In Fig. 2.3 the spectral bands of light emitters of the optopair are given in comparison with methane absorption spectra. Theory of Operation 2-3 DX6106 RMT Ltd Design Features The DX6106 Optical Unit is specially designed for a fast response, high sensitivity, low noise and low power consumption. A number of design features contribute to the performance : The infrared sources are special narrow-band pulsed Light Emitters which operate in microsecond range. The light sources have long life (more then 10,000 hours). Radiation from Light Emitters passes through the gas sampling cell, reflects from the mirror and is focused onto the wide-band Photodetector. Both Light Emitters and Photodetector chips are integrated into a single housing and placed onto a miniature TE cooler for thermostabilization. Heat, dissipated from warm side of the TE cooler, leads to few degrees of overheating of gas sampling cell above ambient. This factor plays a role of vapor anti-condensation at operation in wet conditions. For signal processing the calibrating data of Optical Unit is used. The data is stored in Optical Unit’s EEPROM. 2-4 REV. 1.10/2002 RMT Ltd DX6106 Operation Overview The subsequent description assumes User has already developed, manufactured and connected to the Optical Unit some electronic device for Optical Unit management. (See recommendations in Chapter 3). The order of measurements with DX6106 device is as follows: 1. Firstly, individual calibration of device is required with using of standard gas mixtures. The Detector output signal is non-linear with respect to measuring gas concentration. In spite of theoretical formula the intensity of light which passed through gas sampling cell, is the integral of various optical rays from Light Emitter. Also sensitivity of Detector and performance of Light Emitter are very sensitive to its operating temperatures. Detector’s output signals (both measuring Um and reference Ur channels) must be measured to calculate the following D ratio as a function of known concentration X of standard mixtures. Zero ratio D0 = f(X=0) at zero gas concentration should be used for polynomial extrapolation of calibration results as: U D= m Ur Theory of Operation 2-5 RMT Ltd DX6106 Y= D0 D X = A0 + A1 × Y + A2 × Y 2 + A3 × Y 3 + A4 × Y 4 Calculated coefficients A0 … A4 of polynomial expression and zero ratio D0 may be stored into device internal on-board EEPROM memory. The first calibration is made by Manufacturer. The factory standard calibration uses not less than 5 standard gas mixtures. Several calibrations as above described are made at different ambient temperatures (in a specified operating range) and at corresponding optimal operating temperatures of integrated detector-emitter pair. Up to 15 such calibrations are possible to store for further application. Format of calibration data stored in the EEPROM memory chip after manufacturer calibration is described below in Chapter 3. 2. During routine operation the detector’s output signals should be measured to calculate D ratio. Using known “zero” ratio D0 value Y is calculated. Finally, using known polynomial coefficients A0 … A4 gas concentration X may be calculated with high accuracy. 2-6 REV. 1.10/2002 RMT Ltd DX6106 3. To preserve high accuracy of the device it is necessary to do “zero” adjustments periodically as recommended in Chapter 5. 4. Periodicity of device recalibration is 1 year. It could be done at the factory of Manufacturer, or by a User. Theory of Operation 2-7 DX6106 2-8 RMT Ltd REV. 1.10/2002 RMT Ltd DX6106 3. Construction of Optical Unit The DX6106 Optical Unit (Fig. 3.1 and 3.2) consists of an isolated gas sampling cell (the spherical mirror and the flat mirror with a hole are placed at the end sides) and a new generation integrated optopair with 6102 electronic module. The 6102 Optocomponent Mating Module is connected to optopair’s leads and is fixed with two screws on a bottom cover of the gas sampling cell. Fig. 3.2. DX6106 Optical Unit with optopair detached Construction of Optical Unit 3-1 RMT Ltd DX6106 Gas Sampling Cell The body of gas sampling cell is made of anodized aluminum alloy (Fig. 3.3). It has two gas inlets with 5.0 mm internal diameter. The gas sampling cell can be easily Fig. 3.3. DX6106.C40 gas sampling cell disassembled for service of internal optics (mirrors and optopair). For this purpose both the top and bottom covers can be removed and the optical components extracted out. The gas sampling cell design is shown in Fig. 3.4. Bottom cover Rubber gasket Integrated Spherical optopair mirror Flat mirror with a hole Top cover Rubber Housing gasket Fig. 3.4. Gas sampling cell design 3-2 REV. 1.10/2002 RMT Ltd DX6106 The optical scheme of gas cell is represented in Fig. 3.5. Flat Mirror with a hole Gas Integrated optopair Outlet brunch pipe Spherical Mirror Inlet brunch pipe The main parameters of gas sampling cell are in Table 3.1 Table 3.1. Main parameters of gas Parameter Value No. of passes 4 Total path length, mm 80 Internal volume, ml Construction of Optical Unit 10.4 3-3 RMT Ltd DX6106 The outline dimensions of DX6106.C40 gas sampling cell are shown in Fig. 3.6. 42 27 27 36.5 40 Fig. 3.6 DX6106.C40 gas sampling cell outline dimensions (in millimeters) 3-4 REV. 1.10/2002 RMT Ltd DX6106 Optocomponent The new generation OPRI optopair consists of three optoelements integrated into one case : two narrow-band light emitters (of about 0.1 µm emission band) and one wide-band photodetector. The optopair consists of two special solid state light emitters (light sources) and one sensitive element (photodetector). The peak emission wavelength of one light emitter is near the absorption band of measured gas (measuring channel). The peak wavelength of the other one is out of the absorption band of gas (reference channel). The photodetector has approximately equal sensitivity to signals of both emitters. All the elements of the optopair are mounted onto the cooling surface of a single stage thermoelectric module of 1MT04-059-16 type with an Reference internal thermosensor (Fig. channel emitter 3.7). Measuring channel emitter Photodetector Fig. 3.7. OPRI elements arrangement Construction of Optical Unit A number of steps have been taken to decrease the optoelements mutual influence. The pins layout of the optopair is shown in Fig. 3.8. 3-5 RMT Ltd DX6106 As an example, the parameters of optoelements for methane (CH4) measurements are 12 11 10 t° 1 R 2 introduced in the table bellow: M 4 8 7 + 3 9 5 6 Fig. 3.8. OPxxx optopair pins layout (top view) Element Peak wavelength [ µm ] Bandwidth [ µm ] Measuring channel emitter Reference channel emitter Photodetector 3.23 2.98 3.3 0.1 0.1 2.5 The above table is illustrated with Fig. 3.9. 1.0 Relative response Photodetector 0.5 Reference channel Measuring channel 0 2.0 3.0 Wavelength, µm 4.0 Fig. 3.9. Emission bands of light emitters for methane analyzer 3-6 REV. 1.10/2002 RMT Ltd DX6106 6102 Optocomponent Mating Module The 6102 Optocomponent Mating Module (Fig. 3.10) provides: preamplification of photodetector’s signals, light emitters driving, Fig. 3.10. 6102 Optocomponent Mating Module power supply of photodetector and thermistors with precise voltage. The connectors and optopair location at the 6102 Module’s board is shown in Fig. 3.11. The outline dimensions of 6101 Module are given in Fig. 3.12. 47 System System interface interface Optopair connector X2 connector X1 26 Pin 1 Pin 1 Fig. 3.12. 6102 Module outline Fig. 3.11. Location of the dimensions (in millimeters) connectors and optopair at the 6102 Modules board. Construction of Optical Unit 3-7 RMT Ltd DX6106 X2 8 SCL SDA X2 2 TEC X2 6 +ELED X1 5 OUTS X1 7 OUTT 3 4 6 8 GNDA GNDA GNDA GNDA Filter X1 2 +5VIN Filter X1 1 –5VIN X2 4 GATEM X2 5 GATER X2 3 SOURCE X2 1 GND X2 7 t° + EEPROM X1 X1 X1 X1 Legend t° – TE cooler – Light Emitter – MOSFET switch – thermistor – Photodetector – amplifier Fig. 3.13. Functional Diagram of 6102 Optocomponent 3-8 REV. 1.10/2002 RMT Ltd DX6106 The functional diagram of the 6102 module is drawn in Fig. 3.13. System interface connectors’ pins assignment is given in Tables 3.2 and 3.3. Table 3.2. DX6106 system interface connector X1 pins function description Pin Mnemonic 1 2 3 4 5 6 7 8 –5VIN +5VIN GNDA GNDA OUTS GNDA OUTT GNDA Description – 5V supply input + 5V supply input Ground reference point for analog circuitry and Ground reference point for analog circuitry and Photodetector output Ground reference point for analog circuitry and Thermistor output Ground reference point for analog circuitry and Table 3.3. DX6106 system interface connector X2 pins function description Pin 1 2 3 4 5 6 7 8 Mnemonic GND TEC SOURCE GATEM GATER +ELED SCL SDA Description Ground reference point for power circuitry Cooler power supply input Current sense resistor output Measuring channel LED enable Reference channel LED enable LEDs power supply I2C interface. Synchronization line I2C interface. Data line Construction of Optical Unit 3-9 RMT Ltd DX6106 Preamplifier The preamplifier’s circuit diagram is presented in Fig. 3.14. +5V X1 1 +5VIN –5VIN X1 5 OUTS 3 4 6 8 GNDA GNDA GNDA GNDA X1 2 X1 X1 X1 X1 Fig. 3.14. Simplified diagram of preamplifier of the 6102 module The preamplifier alternatively processes the signals of measuring and reference channels. The preamplifier output signal should be conditioned and then digitized by A/D converter (ADC) with not worse than 12 bit resolution. Recommended outside schematic is placed in Fig. 3.15. 3-10 REV. 1.10/2002 RMT Ltd DX6106 +5V X1 1 +5V –5V X1 5 Attenuator X1 2 X1 X1 X1 X1 ADC Microcontroller DX6106 Optical Unit 3 4 6 8 Fig. 3.15. Output signal processing Within the gas concentration varying scale, the output signal of measuring channel changes by order of value. To preserve accuracy at large measuring gas concentrations it is necessary to use an external amplifier with a variable gain. It is to coordinate the amplified signal with an ADC range. Alternatively, an attenuator may be used. The attenuator can be based on a digital potentiometer chip or D/A converter. It is unnecessary if LEDs pumping current control scheme is implemented. Construction of Optical Unit 3-11 RMT Ltd DX6106 The preamplifier typical output signal waveform is showm in Fig. 3.16. MTB = 20 HS CH1 = .5V Fig. 3.16. Typical output signal waveform 3-12 REV. 1.10/2002 RMT Ltd DX6106 Thermoelectric Cooler The TEC circuit diagram is presented in Fig. 3.17. X2 2 TEC X2 1 GND Driving by TE cooler requires particular attention. First of all, the operation of TE cooler directly affects performance parameters of Optical Unit and gas sensor based on it. Fig. 3.17. Schematics of TE cooler in Second, the TE cooler is the component which consume the largest part of power (Fig. 3.18). The output signal of Photodetector depends very much on its temperature (Fig. 3.19). This ratio is approximately 100%/20 °C. It is equivalent to the temperature drift 1%/0.2 °C. It means that if the thermo-stabilization should be with the accuracy of 0.1°C, then the accuracy of measurements will be 0.5%. The accuracy of thermo-stabilization must be not less than required for gas sensing. Operating temperature of TE cooler must be selected optimal (from Fig. 3.18 and Fig. 3.19): too low temperature stabilization leads to higher power Construction of Optical Unit 3-13 RMT Ltd DX6106 Power, W 2.0 1.5 1.0 0.5 0 –20 –15 –10 –5 0 5 10 Temperature, °C Fig. 3.18. TEC power consumption vs operating temperature Output, V 1.4 1.2 0.8 Um 0.6 1.0 0.8 0.6 0.4 0.4 Ur Um/Ur Um/Ur Ratio 1.6 0.2 0.2 0 –15 –10 –5 0 5 0 10 Temperature, °C Fig. 3.19. Typical preamplifier output vs operating temperature 3-14 REV. 1.10/2002 RMT Ltd DX6106 consumption; at higher temperature the output signals (and signal/noise ratio) are lower. The Optical Unit housing has been designed for additional heat dissipation from warm side of working TE coolers. The maximal heat dissipation is 2 W. At Ta-Top > 40 °C it is necessary to use additional heat dissipation - a bigger heat sink (optional available) or a fan. A developer of thermo-stabilization algorithm has to take into account that time constant of TE cooler is approximately 2 s. An example of recommended scheme of thermostabilization is presented in Fig. 3.20. DX6106 Optical Unit X2 2 +VCC + + X2 1 Construction of Optical Unit PWM Microcontroller GND 3-15 DX6106 RMT Ltd If step-down DC/DC converter is used, the VCC voltage should be not less than 7V to provide the appropriate range of TEC control voltage. The maximum converter’s output current is determined by TECs characteristics behavior. (See Fig. 3.21). Fig. 3.21. Maximal temperature difference vs operating current for 1MT04-059-16. (At zero heat load) As one can see in this diagram, there is some peak current value, the efficiency of TE cooler falls down after that. It is obvious, that the exceeding of this parameter is not meaningful. So 0.5 amp can be considered as an upper bound of a DC/DC converter load. 3-16 REV. 1.10/2002 RMT Ltd DX6106 TE Cooler Specifications TAMB = +20°C Parameter Units Min Typ Max Comments Electrical Parameters Operating T °C Operating Voltage V Operating Current A Resistance Ohm –40 6.8 0.5 11.1 11.7 12.3 1 kHz @ +20°C Dynamical Parameters Time Constant s Construction of Optical Unit 2 3-17 DX6106 3-18 RMT Ltd REV. 1.10/2002 RMT Ltd DX6106 Thermistor UREF RT Filter X1 2 +5VIN X1 7 OUTT 3 4 6 8 GNDA GNDA GNDA GNDA t° For a TE cooler temperature controlling NTC thermistor is mounted onto the cold side of a TE cooler. This thermistor is applied in a scheme with serial loading resistor RL and a reference UREF (Fig. 3.22). RL C X1 X1 X1 X1 Fig. 3.22. Thermistor connection in the 6102 Component list Designation Value RT 2.2 kW ±5% RL 3.83 kW ±0.1% C 0.1 mF, ceramic The typical dependence of thermistor resistance on temperature is presented in Fig. 3.20. The dark area around the curve marks technological deviation determined by resistance and Beta Constant straggling from rated values. Construction of Optical Unit 3-19 RMT Ltd DX6106 30 Resistance, kOhm 25 20 15 10 5 0 –40 –20 0 20 Temperature, °C 40 60 80 Fig. 3.23. Calibration of thermistor vs measured temperature The curve in Fig 3.23 is plotted on the basis of the fundamental equation R = R0 e ( 1 1 b T -T 0 ) (3.1) where b R0 3-20 - Beta Constant, - resistance at standard temperature T0. REV. 1.10/2002 RMT Ltd DX6106 The output signal from thermistor scheme depends on its resistance as : æ ö U TR = U REF çç R L ÷÷ è R L + RT ø (3.2) One can see that the temperature measurement accuracy depends directly on UREF. So the voltage +5VIN on the pin X1/2 must be stable. With the help of equations (3.1) and (3.2) we obtain the plot in Fig. 3.24. 5 Output, V 4 3 2 1 0 –40 –20 0 20 40 60 80 Temperature, °C Fig. 3.24. Thermistor circuit output vs measured temperature Construction of Optical Unit 3-21 DX6106 RMT Ltd It is obvious that the scheme responds to temperature in a nonlinear manner. At the same time over a limited temperature range it is possible to consider the scheme response as linear. It is also obvious that the solution of this problem should be based on the usage of a microcontroller. A look-up table for temperature measurements linearization must be formed in the external memory. The table may be located in the Optical Unit’s EEPROM or in another memory chip. The base points of this table must correspond to the set of operating temperatures of the Optical Unit (See Chapter “Calibration”). In a vicinity of each point the response of the scheme should be linearized. The total number of points must be equal to the number of calibration tables (the number of operating temperatures ranges). The recommended external circuit schematic is presented in Fig. 3.25. Not worse than 12-bit resolution A/D converters (ADCs) are recommended. 3-22 REV. 1.10/2002 RMT Ltd DX6106 DX6106 Optical Unit RT +5V X1 2 t° Filter ADC X1 7 RL C X1 X1 X1 X1 3 4 6 8 Fig. 3.25. Typical thermistor usage Thermistors Specifications TAMB = +20°C; VCC = 5±5% V Parameter Units Resistivity Beta-Constant kOhm K·10-3 Construction of Optical Unit Min Typ Max 2.09 2.2 2.31 2.9 3.1 3.5 Comments @20°C 3-23 RMT Ltd DX6106 Light Emitters + RE C RS RG RG X2 6 +ELED X2 4 GATEM X2 5 GATER X2 3 SOURCE X2 1 GND Fig 3.26. LED drive switches Electronic scheme for Light Emitters driving is shown in Fig. 3.26. The MOSFET transistors are used as a switch keys which are driven by TTL logic levels. The resistors RG in a gate circuits fix closed state of transistors at the absence of activity from external electronic scheme. The sense resistor RS (0.22 Ohm) produces the feedback signal for current stabilization circuit. The typical volt-ampere plot of the Light Emitter is presented in Fig. 3.27. Dark area means technological deviations of Light Emitter performance. The capacitor C together with other external capacitors, serves for accumulation of pulse energy for Light Emitter. Recommended circuit for driving by the Light Emitter is presented in Fig. 3.28. 3-24 REV. 1.10/2002 RMT Ltd DX6106 T = +25°C 5 4 ILED, A Power Supply 5 V (+4…+6 V are available) through resistor R charges the capacitor C in time duration between pulses. Total capacity (the capacitor C and available external ones) must be enough for pulse current stability. 3 Safe Area 2 1 0 2 4 6 ULED, V Fig. 3.27. Typical volt-ampere Component list Designation Value RE 4.7 W ±5% RS 0.22 W ±5% C 2 ´ 220 mF 6.3V Construction of Optical Unit 3-25 RMT Ltd DX6106 DX6106 Optical Unit X2 6 DAC X2 4 DAC X2 5 RS RG RG Microcontroller + RE C X2 3 X2 1 Fig. 3.28. Typical LED control circuit It is advisable in the real design to use some number of analog multiplexors to distribute, for example, the signal of singe DAC into two OPs or output signal of one OP into two MOSFET gates. It will enable to spare some equipment. The current limiting and stabilizing circuit must be implemented essentially into LED driving circuit. It is because of the following reasons: The only current limiting factor is the RS = 0.22 Ohms sense resistor. (The MOSFET RON resistance is negligible in comparison with RS).It 3-26 REV. 1.10/2002 RMT Ltd DX6106 is easy to plot the load line (the curve in Fig.3.X) and to see that the forward current through the LED can run up to 5 amperes if +ELED voltage is chosen as 6V. There is some difference of a photodetector’s response to measuring and reference channel LEDs emittance. To decrease the dynamic range losses, the emitting powers of both LEDs should be balanced. Construction of Optical Unit 3-27 RMT Ltd DX6106 EEPROM EEPROM SCL X2 8 SDA X2 7 The standard Electrically Erasable PROM (EEPROM) 24LC64 chip with two wire serial Fig. 3.21. I 2C interface connection I2C interface is placed on Optical Unit's PCB. It is used for storage of the Optical Unit identification code, calibration data and some additional data for operation of the unit. Additional data are used for operation of the Optical Units with manufacturer's controller DX6101. In no power state the data retention time is more than 200 years. DX6106 Optical Unit +5V EEPROM X2 7 X2 8 X1 X1 X1 X1 1 kW 1 kW X1 2 SCL SDA Microcontroller 3 4 6 8 Fig. 3.22. On-board Memory typical connection The recommended schematic for EEPROM connection is presented in Fig. 3.22. Pay attention to the 1 kOhm resistors that must pull-up the lines of I2C interface. 3-28 REV. 1.10/2002 RMT Ltd DX6106 The detailed description of 24LC64 transfer protocol is possible to obtain, for example, from Data sheet retrieved from Microchip Corporation Web site (http://www.microchip.com). Besides the similar memory devices, are manufactured by other corporations. For example Atmel, Fairchild, ST Microelectronics, etc. EEPROM Specification Parameter Value Volume, bit 16 K (2K´8) Number of re-writing cycles, not less than 10×106 Write speed, ms 5 Construction of Optical Unit 3-29 DX6106 RMT Ltd EEPROM Data Format Various operating parameters can be stored in onboard EEPROM circuit: calibration data, synchronization parameters, measuring mode presets, TE cooling algorithm presets, Optical Unit identification. See recommended EEPROM data structure in Table 3.4. The formats of the First Calibration Data Block is given in Table 3.5. Formats of other reserved (if applied) Calibration Data Blocks are the same as the first one. 3-30 REV. 1.10/2002 RMT Ltd DX6106 *) Item Table 3.4. EEPROM Data Format Address (hex) 1 0000 Calibration data block (first calibration 2 0018 Calibration data block 3 0030 Calibration data block 4 0048 Calibration data block 5 0060 Calibration data block 6 0078 Block of synchronization 7 0082 Block of parameters of measuring 8 008C Parameters of thermostabilization of 9 008C Parameters of thermostabilization of Light 10 008C Optical Unit Identifier Content used only with DX6101 Controller Item Table 3.5. Format of the First Calibration Data Block Address (hex) 1 0000 TE coolers Operating Temperature 2 0002 Ambient Temperature of Calibration 3 0004 “Zero” Value 4 0008 5 Content Name Format Tc Tenv int16 float Polynomial Coefficient A0 d0 A0 0014 Polynomial Coefficient A1 A1 float 6 0020 Polynomial Coefficient A2 A2 float 7 0024 Polynomial Coefficient A3 A3 float 8 0028 Polynomial Coefficient A4 A4 float 9 002C Polynomial Coefficient A5 A5 float 10 0030 Polynomial Coefficient A6 A6 float Construction of Optical Unit int16 float 3-31 DX6106 3-32 RMT Ltd REV. 1.10/2002 RMT Ltd DX6106 4. Installation Tips There are two external power sources required for Optical Unit supply. An external +5V and -5V DC power sources with ±2.5% output tolerance are required for Optical Unit supply. The operating current must be not less than 7.5 mA. The power supplies are to be connected to pins X1/1 and X1/2. They are necessary for supply of: preamplifier of Photodetector, thermistors and sensitive elements of Photodetector, EEPROM. The power supply for customer external electronics depends on scheme concepts. But one must take into account that the total current consumption of Light Emitters and TE Cooler of DX6106 Optical Unit is not more than 300 mA at 0…-5°C operating temperature of TE coolers. For proper Optical Unit operation the ground line should be separated into three wires and joined in the one, close to power supply common terminal. Shielding ground should be in contact with the Optical Unit housing. The recommended connection is shown in Fig. 4.1. Installation Tips 4-1 RMT Ltd DX6106 DX6106 Optical Unit +5V / –5V Converter X1 1 +5V +6¼9.5 V Linear Regulator X1 2 X1 5 X1 7 Control & Measuring Circuits Power supply 0 X2 2 X2 6 X2 4 X2 5 X2 3 X1 X1 X1 X1 3 4 6 8 X2 1 LED & TE Coolers Drivers Signal Ground Power Ground Shielding Ground Fig. 4.1. DX6106 power supplies connection 4-2 REV. 1.10/2002 RMT Ltd DX6106 5. Calibration Preparation First of all User should prepare the set of calibration gases. The number of calibration gases should be at least two more than the desirable polynomial order (See Chapter 2). In turn the order of a polynomial determines accuracy of approximation, and hence the measurement accuracy. The following close to optimum set of calibration gases can be recommended (in percentages to upper concentration of measurement range): Extended Kit Calibration Standard Kit 0 0 1 1 5 5 10 10 15 – 30 – 50 50 65 – 100 100 5-1 DX6106 RMT Ltd Any other sets of standard samples User can apply according to own reasons. But be sure that the samples are within specified measurement range and the customer standard gases provide accurate calibration. As a “zero” gas one can use any standard pure gas. Argon (Ar) or Nitrogen (N2) are quite suitable. As other concentrations, the mixture of measured gas with the “zero” gas is usually used. Prepare some portions of plastic tubes for gas bottles connection with Optical Unit’s gas inlets. In further actions be guided by Chapter 3. 5-2 REV. 1.10/2002 RMT Ltd DX6106 Zero Adjustments To ensure the high accuracy, simple adjustment can be made during operation to adjust “zero” ratio D0. The procedure requires to flow up any "zero" gas through the gas sampling cell. The new D0 coefficient should be stored into EEPROM in place of old value after the completing adjustment procedure (See Chapter 2). Calibration 5-3 DX6106 RMT Ltd Re-Calibration In standard option, the DX6106 Optical Unit is delivered with one calibration data. The calibration is made at optimal operating temperature. User can make re-calibration at any time. It is possible to do this at other operating temperatures, with larger set of reference gases (larger order polynomial) and to replace stored data by the new one. According to customer demands the re-calibration could be done by Manufacturer on request. On-board memory can contain itself additionally 13 data blocks for more calibrations. Totally up to 14 different calibrations could be done. The polynomial coefficients Aj depend on the design of the Optical Unit’s optical scheme. It is not necessary to make re-calibration often. It is recommended to perform re-calibration annually. 5-4 REV. 1.10/2002 RMT Ltd DX6106 6. Maintenance Optics Cleaning If the output signal of either channels (or both) became appreciably less than usually, the Optical Unit’s optics is most likely to require cleaning. Cleaning of optics is executed with the help of suede and the special optic cleaning fluid. For optics cleaning the DX6106 Optical Unit must be disassembled. Remove screws from each end face of the Optical Unit. Remove the covers (Fig. 6.1). Bottom cover Optocomponent Spherical mirror Housing Top cover Rubber gasket Fig. 6.1. DX6106 Optical Unit disassembling illustration Maintenance 6-1 RMT Ltd DX6106 The Optical Unit after disassembling is shown in Fig. 6.2. Fig. 6.2. DX6106 Optical Unit with the The spherical mirror is glued to the top cover. Do not try to rip it off. Clean now the window of the optopair, spherical mirror, internal mirror (with a hole) from both sides. Wait some minutes and assemble the Optical Unit in the reverse order. 6-2 REV. 1.10/2002 RMT Ltd DX6106 7. Standard Kit Item # Code Quan. 1 Optical Unit DX6106 1 2 Interconnection cable DX6100-C-25 1 3 Interconnection cable DX6100-C-26 1 4 Connector’s housing ZHR-8 1 5 Connector’s housing SHR-08V-S-B 1 6 Connector’s shrouded header B8B-ZR 1 7 Connector’s shrouded header BM08B-SRSS-TB 1 8 DX6106 User Manual 1 9 DX6100 software CD 1 Standard Kit 7-1 DX6106 7-2 RMT Ltd REV. 1.10/2002 RMT Ltd DX6106 8. Specifications Common Type Detector NDIR multipass scheme Lead selenide with TE cooler Measured gases Carbon Dioxide Hydrocarbons CO2 CmHn Operation conditions Moisture protection Temperature range Relative humidity IP65 -10° to 50°C 5 to 100% Mechanical Dimensions 4) Weight Specifications 42 ´ 27 ´ 27 mm 60 g (max) 8-1 RMT Ltd DX6106 Carbon Dioxide (CO2) Sensor*) Concentration range 1) 0...1000 ppm 0...5 % vol 0...20 % vol Noise level 2, 3) < 3 ppm < 0.15 % < 0.15 % Accuracy 3) 10 ppm 0,5 % 0,5 % Zero drift 3) 0.02 % Hydrocarbons (CmHn) Sensor*) Concentration range 1) 0...1000 ppm Noise level 2, 3) < 2 ppm < 0.1 % Accuracy 3) 10 ppm 0,5 % Zero drift 3) *) If to use with DX6101 controller. 1) Optional ranges up to 100% vol. are available. 2) At Averaging Time Constant =0.2 s. 3) If value in %, then it means relative units DX/X 4) Without gas inlet pipes and 6102 module. 8-2 0...5 % vol 0.02 % REV. 1.10/2002 RMT Ltd DX6106 9. Ordering Guide XXXXXX . XX . XXX . X Gas Sampling Option A - Aspiration D - Diffusion Concentration Range The largest concentration value, in ppm, includes 2 significant digits followed by the number of zeros to follow Gas Code Code Gas 01 CO2 02 CnHm 03 CH4 04 CO 05 H2O Part Number Example: DX6106.01.504.A [DX6106] DX6106 Series, [01] CO2 Gas Option, [504] [A] Ordering Guide 0...5.0×104 ppm (0...5%) concentration range, aspiration type gas cell, 9-1 DX6106 9-2 RMT Ltd REV. 1.10/2002 RMT Ltd DX6106 RMT Ltd. Leninskij prosp. 53, Moscow 119991 Russia phone: 095-132-6817 fax: 095-135-0565 e-mail: [email protected] http://www.rmtltd.ru Specifications