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LI-COR LI-7500, Instruction Manual

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Table of Contents

Section 1.  Introduction

Overview of the LI-7500 ..............................................................................................................................................................

 

1-1

Getting Started Tutorial ................................................................................................................................................................

 

1-3

Section 2.  Theory of Operation

Relating Absorptance to Concentration........................................................................................................................................

 

2-1

Measuring Absorptance ................................................................................................................................................................

 

2-3

Cross Sensitivity ...........................................................................................................................................................................

 

2-4

Zero Drift ......................................................................................................................................................................................

 

2-5

Equation Summary .......................................................................................................................................................................

 

2-6

LI-7500 Implementation ...............................................................................................................................................................

 

2-9

A Note About Pressure and Temperature .....................................................................................................................................

 

2-11

Summary of Contents for LI-7500

Page 1: ...Analyzer Environmental Division Instruction Manual 7500...

Page 2: ...Open Path CO2 H2O Analyzer Instruction Manual...

Page 3: ...s that the product Product Name Open Path CO 2 H 2 O Infrared Gas Analyzer Model Number s LI 7500 Product Options None conforms to the following Product Specifications Supplementary Information The pr...

Page 4: ...ight 2001 LI COR Inc Publication Number 984 06360 Revision 1 April 2001 Revision 2 November 2002 Revision 3 July 2003 Revision 4 January 2004 Printing History New editions of this manual will incorpor...

Page 5: ...7500 1 1 Getting Started Tutorial 1 3 Section 2 Theory of Operation Relating Absorptance to Concentration 2 1 Measuring Absorptance 2 3 Cross Sensitivity 2 4 Zero Drift 2 5 Equation Summary 2 6 LI 750...

Page 6: ...cations Software on Your Computer 3 10 Operation Using the LI7500 Software 3 10 Connect Page Establishing Communications 3 11 Calibration Page Setting the Zero and Span 3 13 Cal Coefficients Page 3 16...

Page 7: ...are Zero and Span 4 2 Checking the Zero Considerations 4 3 Checking the Span Considerations 4 3 What Actually Happens 4 4 Complete Step by Step Calibration Instructions 4 7 Section 5 Maintenance Clea...

Page 8: ...tion Problems 6 2 Bad Temperature or Pressure Readings 6 3 Bad CO2 or H2O Readings 6 4 Diagnostic Messages 6 5 LI7500 Error Messages 6 9 Appendix A Specifications Appendix B Pin Assignments Appendix C...

Page 9: ...LI 7500 s important features include Simultaneous measurements of CO2 and H2O in the free atmosphere High speed measurements Internal 150 Hz measurements are digitally filtered to provide a true 5 10...

Page 10: ...Spare Parts Kit part 9975 007 This kit contains replacement parts for your LI 7500 Among other items the spares kit contains cables and fuses serial adapter cable tubing and control box mounting brack...

Page 11: ...xternal temperature and or pressure transducers to the LI 7500 See Calibration Section 4 for details DAC Output Cable part 392 05622 Used for DAC outputs from the LI 7500 LI7500 Data Communications So...

Page 12: ...briefly covers the basic steps you might follow to set up the LI 7500 to collect and record data Many of these steps are described in greater detail elsewhere in this manual 1 Connect the Sensor Head...

Page 13: ...ble 392 05619 has a circular connector that attaches to the LI 7500 control unit front panel at the location shown in Figure 1 2 The other end has bare wire leads for connection to a 10 5 30VDC supply...

Page 14: ...omputer 4 Connect the RS 232 Cables For convenience when operating the LI 7500 in the laboratory a short adapter cable 9975 015 is provided for connecting the instrument to your computer a Open the co...

Page 15: ...Introduction 1 7 9975 015 Serial Adapter Cable Adapter Cable Unplugged Internal RS 232 Connector Power Supply Connector Plug in here Figure 1 2 Unplug the internal RS 232 connector and plug in the ada...

Page 16: ...ed on the calibration sheet for the sensor head being used Sensor heads are interchangeable but the calibration coefficients as well as the zero and span parameters on the Calibration page are unique...

Page 17: ...ectly at 100 but there is not much room for further compensation so the windows should be cleaned before it reaches 100 10 Optional Verify Calibration If you have facilities to check zero and span do...

Page 18: ...rber of some gas ui mol m 2 and absorption in a band are related by some function hi then i ei P h u P i i ei 2 1 The subscript i denotes a particular ith gas Pressure is denoted as Pei because it is...

Page 19: ...h P 1 2 2 We rewrite Equation 2 2 as i ei i i ei P P f 2 3 by combining and the inverse h functions into a new function fi The calibration function fi is generated by measuring a range of known densi...

Page 20: ...f gas i present and o is the transmitted radiant power in the absorption band with zero concentration of i present The LI 7500 approximates absorptance by i i io A A 1 2 6 where Ai is the power receiv...

Page 21: ...2 and H2O respectively there is a slight cross sensitivity between gases due to imperfections in the detector s frequency time response This varies from detector to detector but is measured during cal...

Page 22: ...ature drift as ambient temperature changes This error is directly related to the detector cooler control voltage which is measured and thus provides a mechanism for a software fine tuning The zero ter...

Page 23: ...e total pressure P Pew P 2 11 H2O absorptance w is from Equations 2 8 and 2 10 w w wo cw c co wo w d A A X A A Z Z V 1 1 2 12 where Xcw is the cross sensitivity factor for CO2 on water vapor H2O XS on...

Page 24: ...ressure of Pec CO2 A method of doing this LI COR Application Note 116 is Pec P mw 2 14 where mw 1 aw 1 mw 2 15 and mw is the mole fraction of water vapor aw has been determined to be 1 15 for the LI 7...

Page 25: ...Section 2 2 8 Theory of Operation CO2 molar density c mmol m 3 is c ec c c c ec P f S P 2 17 The coefficients for the 5th order polynomial fc are given on the calibration sheet...

Page 26: ...ressure Pg kPa and temperature Tg C are measured by sensors in the control box Figure 2 1 Their values are displayed on the Calibrations page Thermistor Tubing connected to pressure transducer Figure...

Page 27: ...calculations Label Description Equation H2O mmol m3 H2O number density W P f S P g w w w g 2 18 H2O g m3 H2O mass density W W m 18 1000 2 19 H2O mmol mol H2O mole fraction W WR T P f g g 273 15 1000...

Page 28: ...re is not required for the calculation and accurate pressure measurement is not needed either Equations 2 18 and 2 22 For example a 5 error in pressure typically leads to a 1 error in density for CO2...

Page 29: ...When computing mole fraction however temperature and pressure do need to be known as accurately as possible Here errors in pressure and temperature are directly proportional to errors in mole fraction...

Page 30: ...holes in the four corners of the box as well that can be used to attach the box directly to a flat surface if desired The mounting brackets are designed to accomodate a square or circular mounting po...

Page 31: ...3 2 Setup and Operation Control Box Socket Head Screws 4 Side View Top View Post U bolt Nut LI 7500 Control Box Mounting Bracket Figure 3 1 Attach mounting brackets to control box and secure to mount...

Page 32: ...termine the height at which the sensor head will be mounted and plan to mount the control box accordingly 2 The thermal properties of the control box are such that it is OK to place the box in direct...

Page 33: ...The mount is threaded to accept standard 3 8 16 tripod screws a 1 4 20 adapter is also included which can be threaded into the mounting post Mounting the sensor head at a slight angle from vertical 10...

Page 34: ...sor head should be placed as close to and downwind of the sonic anemometer as possible and at equal heights as shown in Figure 3 2 Serial Cable Connection There are three serial cables provided for va...

Page 35: ...al RS 232 connector located on the PC board as shown in Figure 1 2 This cable can be used for in the laboratory convenience The Serial Adapter Cable has a 6 pin connector on one end and a 9 pin DB typ...

Page 36: ...16 This is a null modem cable that is used to interface with devices such as computers serial printers and terminals with 9 pin serial ports If you want to interface to a device with a 25 pin serial p...

Page 37: ...emale Connector 9 Pin Male Connector 25 Pin Serial Port Standard Serial Cable LI 7500 Internal Connector 9 Pin to 25 Pin Adapter 6 Pin Eurofast Cable Standard Serial Cable LI 7500 External Connector o...

Page 38: ...nside of the control box that shows wire connections it can also be found in Appendix B Connect the Ground wire black to the negative input on your datalogging device and the DAC1 brown or DAC2 blue w...

Page 39: ...ll be placed in the Programs menu NOTE To remove the software go to the Control Panel and select Add Remove Programs Choose LI7500 from the list of programs and click the Add Remove button Operation U...

Page 40: ...ial COM port baud rate and data acquisition frequency in Hz are chosen in this page Click on the Connect button to establish communications with the LI 7500 Click on Disconnect to terminate communicat...

Page 41: ...Section 3 3 12 Setup and Operation...

Page 42: ...cquisition Frequency below to be used while the program communicates with the LI 7500 Select from 9600 19200 or 38400 Data Acquisition Frequency This is the update frequency to be used while the LI750...

Page 43: ...Section 3 3 14 Setup and Operation...

Page 44: ...2 Zco see Equation 2 16 and between 0 65 and 0 85 for H2O Zwo see Equation 2 12 It is recommended that you track these values over time as you re zero the instrument As the internal chemicals lose the...

Page 45: ...displays these factory determined calibration coefficients as well as a factor for correcting CO2 measurements for band broadening due to the presence of water vapor and a zero drift correction facto...

Page 46: ...Section 3 Setup and Operation 3 17...

Page 47: ...window back to the state they were in before editing The Head Serial Number displays the serial number of the LI 7500 sensor head that is associated with the coefficients When exchanging sensor heads...

Page 48: ...ibrated analyzer from its control box use the Save Configuration As entry in the File menu to store the configuration information in a file Then to move this head to another control box 1 Attach the s...

Page 49: ...be identified by a green LED visible during operation below When moving calibration information from one control box to another with different board revisions the IRGA must be zeroed and spanned Sect...

Page 50: ...Section 3 Setup and Operation 3 21 Inputs Page Temperature Pressure and Auxiliary Inputs...

Page 51: ...and pressure values are obtained they can be measured with the on board sensors via a custom sensor measured at the Aux Input port or hand entered For temperature or pressure measured via the auxiliar...

Page 52: ...n using the Update Selected button Click on Cancel All to restore any edited values in this page to their original state Using Auxiliary Inputs The LI 7500 has two auxiliary input channels that can be...

Page 53: ...b selections To calculate concentration from density data would require post processing using the equations found in Table 2 21 The LI 7500 auxiliary input is a 12 bit differential input The input ran...

Page 54: ...unshielded thermistor will result in significant measurement errors The blue and gray wires inside the enclosure are not connected to the green screw terminal block when the instrument ships from the...

Page 55: ...radio button of the Inputs Tab to activate this selection The LI7500 software assumes you are entering a slope in units of degrees or kPa per VOLT In the example using an external temperature sensor l...

Page 56: ...Section 3 Setup and Operation 3 27...

Page 57: ...s that the internal thermistor is perpetually exposed to a temperature that is higher than the actual ambient air The LI 7500 internal absolute pressure sensor has a range of 15 115 kPa Its accuracy b...

Page 58: ...Section 3 Setup and Operation 3 29...

Page 59: ...full scale select CO2 mmol m3 under DAC1 Source and set 0V 0 and 5V 20 0V 0 Xo zero volts corresponds to 0 mmol m3 5V 20 XF full scale corresponds to 20 mmol m3 When a voltage range R is selected the...

Page 60: ...etting the delay count of the LI 7500 to 17 yields a total delay of 297 seconds which means the LI 7500 data will have a delay of 3 execution intervals 0 297 s 0 1 s which the logger can allow for in...

Page 61: ...dwidth Bandwidth 5 10 or 20 Hz determines the signal averaging done by the digital filter To avoid aliasing only a concern for co spectra not for fluxes one should sample the LI 7500 at a frequency gr...

Page 62: ...ich there are fluctuating gas concentrations Given a sinusoidal oscillation of concentration the instrument s ability to measure the full oscillation amplitude diminishes as the oscillation frequency...

Page 63: ...meter 3 in the SDM LI7500 instruction defines what data are sent to the datalogger from the LI 7500 Parameter 3 can take on values between 0 and 6 See Table 3 1 for parameter 3 value definitions Table...

Page 64: ...ol m3 CO2 absorptance H2O absorptance Pressure kPa Temperature C Aux channel user units Cooler signal Volts Diagnostic value see below Bandwidth Hz Delay interval 5 CO2 mmol m3 H2O mmol m3 Pressure kP...

Page 65: ...sent to the LI 7500 for implementation by selecting the appropriate check boxes under Values to Update and then clicking the Update Selected button RS 232 Page Setting RS 232 Output for Unattended Lo...

Page 66: ...value The index value is incremented every 6 5 milliseconds e g 152 Hz and ranges from approximately 2 0E8 to 2 0E8 Use the Baud Rate pull down menu to select from 9600 19200 or 38400 baud Use the Fr...

Page 67: ...Section 3 3 38 Setup and Operation...

Page 68: ...s is shown below Data format with labels Data Ndx 1545 DiagVal 250 CO2Raw 1 5386712e 1 CO2D 3 2183277e1 H2ORaw 3 5775542e 2 H2OD 1 9687008e2 Temp 2 4227569e1 Pres 9 8640356e1 Aux 0 Cooler 1 5756724 Da...

Page 69: ...The PC Logging Page is used to configure the data output parameters used while the LI7500 program is active On this page you specify the destination file information to appear in the file header the...

Page 70: ...Section 3 Setup and Operation 3 41...

Page 71: ...sing tab or space delimited text Log Values Click on the Log Values check boxes to choose the variables to be output Relative Time is seconds since the Start button was pressed Strip Charts Page Viewi...

Page 72: ...Setup and Operation 3 43 smooth scrolling refreshes the chart after each data point is added after data run off the right edge of the chart and coarse scrolling moves the chart approximately 1 2 page...

Page 73: ...er making changes press Start again The physical size of the strip chart will follow the window size so for a bigger chart enlarge or maximize the program s window TIP You can rescale both Y axes of a...

Page 74: ...ics page allows you to view the current operational state of the LI 7500 including values of CO2 and H2O absorptance optical bench properties and the current analyzer configuration See Section 6 Troub...

Page 75: ...the LI 7500 configuration status Menu Description File Menu The File menu contains commands that allow you to open and save existing configuration files and to exit the program When you choose Open C...

Page 76: ...Section 3 Setup and Operation 3 47 After you have selected a configuration file and clicked Open the Select dialog appears below...

Page 77: ...ect only certain portions of the configuration file to be opened useful if you don t want to overwrite some of your present settings in the LI 7500 software For example to select only the strip chart...

Page 78: ...ese items sent to the LI 7500 as well NOTE If you leave Update LI 7500 unchecked the selected configuration items will still show up on the PC program s windows from where you can update the LI 7500 i...

Page 79: ...reen showing the current version number of the LI7500 software Help Topics opens the LI 7500 Help file where you can select from a list of help topics Operational Considerations Dew The LI 7500 can to...

Page 80: ...nd if a droplet or flake is in the path for a sample measurment but out of the path for a reference measurement or vice versa it will influence the resulting reading Figure 3 4 illustrates a strip cha...

Page 81: ...Section 3 3 52 Setup and Operation Figure 3 4 Typical strip chart trace taken during a light snow shower The higher the bandwidth the more pronounced this effect since less averaging is done...

Page 82: ...of 152 Hz the bandwidth Thus if the bandwidth is 10Hz the frequency problem range is 142 to 162 Hz and upper harmonics The instrument is completely insensitive to vibrations slower than this and very...

Page 83: ...etting zero and span During a factory calibration both of these steps are performed The values of the coefficients that are determined should be valid for several years The zero and span adjustments a...

Page 84: ...h period but you might want to check it after an extreme temperature change 30 C The analyzer s span is affected by temperature pressure and the state of the internal chemicals Temperature A 10 C chan...

Page 85: ...the air in the cylinder really is CO2 free since a typical cylinder of standard grade nitrogen might have as much as 20 ppm of CO2 in it Compressed cylinders may be at pressures of several thousand po...

Page 86: ...d span calibrations can be done separately In general if reliable calibration standards are not available or if there is not enough time to do the job properly it is better to leave the zero and span...

Page 87: ...wc w wo c d 1 4 1 Similarly Z A A X A A Z V wo w wo cw c co w d 1 4 2 When the span is set the value of Sc or Sw for water is determined For example if there is a known CO2 density c in the optical p...

Page 88: ...ion so S f P P c c c ec ec c 1 4 3 c is given by 2 16 In terms of a known mole fraction m c instead of a known density S f m P P RT P c c ec ec c 1 4 4 If the CO2 concentration is dry then Pec P so S...

Page 89: ...y Step Calibration Instructions 1 Run the program see Section 3 Then select the Calibration tab in the Main Window of the 7500 50 Communications software 2 Place the calibration tube into the sensor h...

Page 90: ...Section 4 4 8 Calibration Calibration Tube insert this end first Air In Air Out Pressure optional Thermistor Figure 4 1 Flow calibration gas at the Air In port shown...

Page 91: ...as before the fixture was inserted The fixture is very easy to center if it looks centered it probably is NOTE The three ports are entirely interchangeable 3 Click on the Calibration tab and verify t...

Page 92: ...o Check the resultant value of Zco shown on the Zero CO2 page Figure 4 2 It should be near 1 typically between 0 85 and 1 1 This value will steadily increase as the internal chemicals lose effectivene...

Page 93: ...ically 0 9 1 1 Span H2O 13 To set the H2O span flow air of known dew point through the calibration tube at about 0 5 to 1 0 LPM To avoid condensation use a dew point temperature several degrees below...

Page 94: ...obstructed The windows are sapphire and are extremely durable and resistant to scratches clean the windows with any mild detergent or glass cleaner Also coating the windows with a water resistant win...

Page 95: ...below in Figure 5 1 is from a long term test on a roof top on a snowy day January 2001 in Lincoln NE Note the small puddle of water on the sapphire window the AGC value was at 100 Figure 5 1 Water on...

Page 96: ...a 5A 250V 5 20 mm fast blow type fuse located on the main circuit board inside the control unit case Figure 5 2 If the battery or other power source fails to power the LI 7500 check to see if the fuse...

Page 97: ...the detectors free of CO2 and water vapor These bottles should be recharged with fresh chemicals on an annual basis Replacement charged bottles are available from LI COR in sets of two under part num...

Page 98: ...Section 5 Maintenance 5 5 Mounting Bracket Remove these 2 screws Washer Spacer Figure 5 3 Remove the 2 screws on the base of the mounting bracket...

Page 99: ...d magnesium perchlorate Figure 5 4 Fill the bottles half full with Ascarite II first followed by the magnesium perchlorate Place a filter paper disk in the lid to keep the chemicals from spilling into...

Page 100: ...cover retention screw Insert 6 32 screw here to act as a knob for removal Bottom View Side View Figure 5 5 Remove the screw holding the bottle covers and replace the chemicals 4 Insert the recharged...

Page 101: ...by setting the CO2 and H2O zeros Check the zero again if possible after one or two days NOTE LI COR has written a publication that describes the use of chemical scrubbing agents with LI COR gas analy...

Page 102: ...the box near the fuse Fig 5 1 will light up for about 5 seconds then if operating correctly go off and remain off If any of the diagnostics listed below become true during the operation of the instru...

Page 103: ...ts RS 232 configuration back to what it was originally or to that set up in the RS 232 panel Port in use or does not exist when connecting This message indicates that the COM port setting on the Conne...

Page 104: ...ts that appear on that same page If the source is User Entered then whatever you enter in the text boxes is used for the value Temperature is Measured and reads 65 or so The thermistor is broken or di...

Page 105: ...re the temperature and pressure make sense and that the current values of zero and span are near 1 Absorptances make sense densities don t If the absorptance value displayed on the Diagnostics page se...

Page 106: ...e to a hand entered constant value to try this Check the calibration coefficients and band broadening value if the problem is with CO2 to make sure they are correct Diagnostic Messages The Diagnostics...

Page 107: ...Section 6 6 6 Troubleshooting...

Page 108: ...C Note that this does not always indicate a serious problem the cooler may simply have not yet reached the target temperature during instrument startup or it may be out of range due to external enviro...

Page 109: ...er If this value gets below 0 05 it may be too cold the detector may not be temperature controlling This will typically be at 30 C or below AGC Note this value when you first operate the LI 7500 Typic...

Page 110: ...e The baud rate selected is not fast enough to keep up with the data acquisition frequency Not able to connect to the LI 7500 successfully Initial data exchange did not occur successfully Check to see...

Page 111: ...ined errors The configuration sent from the LI 7500 did not parse correctly Attempt to reconnect Enter a valid DAC Source Select a DAC source from the list Error found in configuration file The file c...

Page 112: ...based software supports all setup configuration and calibration functions through RS 232 serial port Outputs RS 232 20 Hz Maximum SDM 40Hz 2 user scalable 16 bit DACs updated at 300 Hz Auxiliary Inpu...

Page 113: ...mol H2O RMS noise at ambient 370 ppm PSD 35 ppb mol mol 1 mmol m 3 mg m 3 0 3000 0 117 0 5148 0 08 0 11 0 16 0 0031 0 0043 0 0061 0 13 0 19 0 27 0 3 0 1 0 012 0 004 0 5 0 2 0 1 0 02 4 00E 05 2 00E 05...

Page 114: ...Diff In BRN Diff In RED Thermistor 2 5V BLU Thermistor In GRY Earth Ground WHT Auxiliary Inputs 1 6 1 6 The sensor head is connected to two terminal strips at the upper righthand corner of the main c...

Page 115: ...ppendix B Green White Orange Yellow Blue White Yellow White Orange White Gray White Violet White Sensor Head 1 4 Black White Brown White Gray Black White Brown Blue Green Violet Red White Red Shield S...

Page 116: ...ve at the time of this printing In some cases the information may change without notice Soda Lime 6 12 mesh and Magnesium Perchlorate Anhydrous Mg ClO4 2 GFS Chemicals P O Box 245 Powell OH 43065 Phon...

Page 117: ...000 Toll free FAX 800 926 1166 www fishersci com Soda Lime Part S201 212 LI COR Part 9960 071 Mg ClO4 2 Part M54 500 500g Thomas Scientific P O Box 99 Swedesboro NJ 08085 6099 Phone 609 467 2000 FAX 6...

Page 118: ...4785 Phone 201 467 6400 FAX 201 379 7415 Toll free 800 776 7000 Toll free FAX 800 926 1166 www fishersci com MAX17731 8 20 Mesh Thomas Scientific P O Box 99 Swedesboro NJ 08085 6099 Phone 609 467 2000...

Page 119: ...nect to the LI 7500 LI COR Part Number LI 7500 Control Box Connector Cable Connector Type Turck Part Number 392 05618 SDM Interface 5 pin female RK 4 5T S90 392 05619 Power 3 pin female KB 3T S90 392...

Page 120: ...d data sent by the LI 7500 comes packaged in a particular way For example to set the Bandwidth to 10Hz the following string Outputs BW 10 should be sent followed by a line feed character decimal 10 Ea...

Page 121: ...ted with carriage return and line feeds equally as well Another example of a command string is Outputs RS232 Freq 10 Pres TRUE BW 5 In this case we are setting the RS 232 output frequency to 10Hz requ...

Page 122: ...this Data CO2D 2 2083146e1 H2OD 3 5485935e2 Temp 2 5886261e1 Pres 9 8157062e1 This record is showing the latest values of CO2 and H2O mole density mmol m 3 temperature C and pressure kPa The fields p...

Page 123: ...command Command Summary In the following sections some abbreviations are used int means an integer value such as 0 10 452 etc float means any integer or floating point value such as 0 3 14159 1E 7 3...

Page 124: ...2 Table 1 The Outputs Command Command Subcommands Remarks BW 5 10 20 Sets instrument bandwidth to 5 10 or 20 Hz Delay int Output delay interval 0 to 32 where each interval is 1 152 seconds This is add...

Page 125: ...puts RS232 Aux bool CO2Raw bool These commands determine what is included in the Data output record CO2D bool H2ORaw bool H2OD bool Cooler bool EOL hex code s User defined termination character s for...

Page 126: ...d approximately every 6 5 milliseconds e g 152 Hz and ranges from approximately 2 0E8 to 2 0E8 DiagRec bool Controls whether independent Diagnostic text records are ever sent If TRUE operates normally...

Page 127: ...transmitted in the normal Data format record When Labels FALSE however data output are values only and are tab delimited To maximize available bandwidth when Labels FALSE a data record might appear as...

Page 128: ...CO2D 3 2183277e1 H2ORaw 3 57 75542e 2 H2OD 1 9687008e2 Temp 2 4227569e1 Pres 9 8640356e1 Aux 0 Cooler 1 5756724 Data Ndx 1809 DiagVal 250 CO2Raw 1 5380490e 1 CO2D 3 2162146e1 H2ORaw 3 57 57541e 2 H2O...

Page 129: ...Labels FALSE lf Received from LI 7500 252 250 0 15401 32 2167 0 03569 196 703 24 33 98 6 0 1 5730 511 250 0 15404 32 2174 0 03572 196 816 24 42 98 5 0 1 5683 765 250 0 15402 32 2342 0 03579 196 995 2...

Page 130: ...8799e 1 CO2D 3 2176308e1 H2OD 1 9711704e2 Temp 2 4171295e1 Pres 9 8543587e1 Aux 0 Cooler 1 5700240 LABELS FALSE Value Floating Point Example CO2Raw H2ORaw Aux x xxxxx 0 12345 CO2D xx xxxx 15 1234 H2OD...

Page 131: ...0 to output only CO2 and H2O molar densities once every 2 seconds Outputs RS232 Freq 5 Pres FALSE Temp FALSE Aux FALSE CO2Raw FALSE CO2D TRUE H2ORaw FALSE H2OD TRUE Cooler FALSE 2 To configure DAC 1 t...

Page 132: ...ts RS 232 port The frequency with which it outputs Data records is deter mined by the Outputs RS232 Freq command shown in Table 1 Data and status record formats are determined by the Outputs RS232 boo...

Page 133: ...he values included are set Data Aux float Auxiliary input value by Outputs RS232 How CO2Raw float CO2 absorptance often this is output is CO2D float CO2 density mmol m 3 determined by H2ORaw float H2O...

Page 134: ...put at 1 Hz Path float The AGC value in 0 100 Ack Received TRUE Sent by the LI 7500 to aknowledge any incoming command Val float Only sent after zeroing and spanning commands Contains the new computed...

Page 135: ...ed to the LI 7500 the record is built as presently defined Labels TRUE or FALSE etc and is added to the output queue This software command is normally used when the update frequency is set to zero as...

Page 136: ...tand that RS 232 logic TRUE 1 is considered a low or negative voltage and logic FALSE 0 is considered a high or positive voltage Thus the CTS toggle sequence would look like 50 sec V logic 0 0V V logi...

Page 137: ...end Output 8 CTS Clear To Send Input 9 RI Ring Indicator Input A possible wiring configuration using the LI COR RS 232 cable part 392 05620 to a computer would be LI COR CABLE DB9 ON HOST COMPUTER Col...

Page 138: ...igger actually sends a request to the data router task in the DSP to output a single data record over the RS 232 port The processing that is incurred to do this is relatively lengthy The RS 232 task i...

Page 139: ...mand Subcommands Remarks Source Aux Measured UserEntered How it is determined Pressure Temperature Val float Fixed value for UserEn tered Inputs Aux A float Slope B float Intercept Examples 1 To make...

Page 140: ...Source Measured Temperature Source Measured The Calibrate and Coeffs Commands The Calibrate and Coeffs commands control zeroing spanning and factory calibration coefficients The Date subcommand must b...

Page 141: ...quoted string The date field triggers the LI 7500 to do a zero immedi ately The new value will be returned in an Ack record Calibrate Val float For setting the span directly If not present will trigg...

Page 142: ...ng The 75H xxxx head number Band A float The band broadening coeffi cient 1 15 for the LI 7500 A float B float C float CO2 D float Coeffs Current E float These values are found on the XS float LI 7500...

Page 143: ...will be sent in the next Ack Val record See Table 2 2 To force the H2O channel to use the value 0 96 for its zero send this Calibrate ZeroH2O Val 0 96 3 To make the LI 7500 set its CO2 span right now...

Page 144: ...main board It is generally only used to access lower level software for updating the embedded program or when the instrument is not responding normally Table 5 Synchronization Commands Command Remarks...

Page 145: ...ts Data Diagnostics EmbeddedSW Inputs The query for individual parameters works only for configuration parameters and not data or diagnostic information All commands are followed by a line feed lf Exa...

Page 146: ...2000 at 1 43 59 PM ZeroCO 2 Val 1 3099210 Date Aug 29 2000 at 4 26 54 PM SpanH2O Val 9 8932171e 1 Target 1 5020001e1 Tdensity 5 7752504e2 Date 16 Jul 2000 at 18 54 26 Spa nCO2 Val 1 0034980 Target 9 9...

Page 147: ...aud 38400 Freq 0 Pres TRUE Temp TRUE Aux TRUE Cooler TRUE CO2Raw TRUE CO2D TRUE H2ORaw TRUE H2OD TRUE Ndx TRUE DiagVal TRUE DiagRec FALSE Labels FALSE EOL 0D0A Data lf causes a Data record to be put i...

Page 148: ...an EmbeddedSW record to be put in the output queue Example Response EmbeddedSW Model LI 7500 CO2 H2O Analyzer Application Version 2 0 Inputs lf causes an Inputs record to be put in the output queue Ex...

Page 149: ...s RS232 EOL bool DiagRec bool Ndx bool Labels bool DiagVal bool LI7500 Windows Program Extensions The LI7500 Windows program extends the configuration grammar to store various settings used by the pro...

Page 150: ...g Strip chart left variable LMax float Left axis max value Lmin float Left axis min value RV quoted string Strip chart right variable Chart Rmax float Right axis max value Rmin float Right axis min va...

Page 151: ...ud 9600 19200 38400 Connect Freq float Value between 0 and 20 0 Port int Value between 1 and 38 CI bool Include cal information Del Space bool Which delimiter Tab bool Log Name quoted string Log file...

Page 152: ...n bool CO2 mmol m 3 CdenMg bool CO2 mg m 3 Cmf bool CO2 mol mol 1 Dew bool H2O Dew point C Log LogVals Habs bool H2O absorptance Hden bool H2O mmol m 3 HdenMg bool H2O g m 3 Hmf bool H2O mmol mol 1 Po...

Page 153: ...LI 7500 and you wish to get the LI 7500 to send its configuration to you then this protocol must be used Establishing Communications Step by Step 1 Set a break condition on the RS 232 line 500 ms shou...

Page 154: ...0D0A Inputs Pressure Source Measured UserVal 9 8000002e1 Temperature Source Measured UserVal 2 5000000e1 Aux A 1 B 0 Calibrate ZeroH2O Val 1 0166603 Date Feb 2 2001 at 10 12 21 AM ZeroCO2 Val 1 56451...

Page 155: ...al Division 4421 Superior Street P O Box 4425 Lincoln Nebraska 68504 USA Phone 402 467 3576 FAX 402 467 2819 Toll free 1 800 447 3576 U S Canada E mail envsales env licor com Internet http www licor c...

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