COZIR™ Sensor User's Guide
Contents
1. E o z b o P Q v 8 Filter Setting Increasing the filter setting has a beneficial impact on noise so improves the sensor resolution It also slows the sensor response to transients This can be used to improve the detection of average CO2 conditions In building control for example a fast response to breathing near the sensor is undesirable If the transient response is important either for speed of response or because the shape of the transient is required a low filter setting should be used The following chart shows the same transient event capture using a filter setting of 4 and using a filter setting of 32 Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential responsibility is assumed by GSS Ltd for its use Rev B 12 13 Release www gassensing co uk GSS Ltd 2011 2013 Effect of Filter on Transient Response 12000 10000 8000 Filter 4 6000 Filter 32 Reported CO2 4000 2000 8 1 2 Setting the Digital Filter To change the setting type A r n where 774 is the required filter setting For most applications a filter setting of 32 is recommended send A 32 r n response A 00032 r n If the filter is set to zero a smart filter mode will be used in which the filter response is altered to suit the prevailing conditions This is useful if there is a combination of steady state conditions w2. 4 Output Fields The COZIR sensor can be configured to output up to five fields of information Typically the only fields of interest are the CO concentration Temperature if fitted and Humidity if fitted This allows users to customise the output string transmitted by the sensor Up to five values can be transmitted in the string The format is always the same each field is identified by a single character followed by a space followed by the five digit number indicating the value of the parameter The output fields can be set by sending a command of the format M 12345 r n where 12345 represents a mask value which defines the output fields The mask value is created by adding the mask values for the parameters required see table below The sensor will output a maximum of five fields If the mask setting represents more than five fields only the first five those with the highest mask values will be output SprintIR sensors have a limited time to transmit information so no more than two fields should be selected for output Parameter Field Mask Comments Identifier Value Humidity H 4096 Reports the humidity output of the Temperature and Humidity Sensor if Fitted D digitally filtered d 2048 Reports a value related to the normalized LED signal strength smoothed D unfiltered D 1024 Reports a value related to the normalized LED signal strength Zero Set Point h 256 Report
3. NB e All commands must be terminated with a carriage return and line feed lt CR gt lt LF gt In this document this is shown as r n e Commands which take a parameter always have a space between the letter and the parameter e The sensor will respond with a if a command is not recognized The two most common causes are missing spaces or missing lt CR gt lt LF gt terminators Command Use Example Response A r n Set the digital Filter A16 r n A00016 r n See User Settings a r n Return the digital a r n a 00016 r n See User Settings filter setting F HHHHH HHH r n Fine Tune the zero F 410 400 r n_ F33000 r n See Zero Point Calibration point G r n Zero point G r n G 33000 r n See Zero Point Calibration calibration using fresh air H r n Return most recent H r n H 00552 r n 55 2 in the example humidity Humidity sensing is a factory measurement K r n Selects the K 1 r n K 00001 r n See Operating Modes operating mode M HHHH r n Sets the output M 6 r n M 00006 r n See Output Fields fields P HHH HN Sets a user P110 r n P 00001 00010 r n See User Settings configurable field in EEPROM p r n Reads a user p 10 r n p 00010 00001 r n See User Settings configurable field from EEPROM Q r n Return most recent Q r n See Command Reference fields S HHHH r n Sets the span S 81
4. Sets a user configurable parameter Syntax P SPACE followed by an up to 2 digit number SPACE followed by an up to 3 digit number terminated by OxOd Ox0a CR amp LF Response P 00001 00010 r n see User Settings for details p COMMAND 0x70 USER CONFIGURATION Example p 10 r n Description Returns a user configurable parameter Syntax P SPACE followed by an up to 2 digit number terminated by OxOd 0x0a CR amp LF Response P 10 1 r n see User Settings for details 9 2 Information Y COMMAND 0x59 INFORMATIO Example Y r n Description the present version string for the firmware Syntax ASCII character Y terminated by 0x0d Ox0a CR amp LF Response Y Jan 30 2013 10 45 03 AL17 r n B 00233 00000 r n NB This command returns two lines split by a carriage return line feed and terminated by a carriage return line feed This command requires that the sensor has been stopped see K command COMMAND 0x59 INFORMATIO Example r n Description Returns a number of fields of information giving information about the sensor configuration and behavior Syntax ASCII character terminated by OxOd 0x0a CR amp LF Response Contact GSS for details COMMAND 0x2E INFORMATIO Example ME Description Returns a number indicating what multiplier must be applied to the Z or z output to convert it into ppm Syntax ASCII character terminated by 0x0d Ox0a CR amp LF
5. if fitted Subtract 1000 and divide by 10 to get the temperature in C Syntax ASCII Character T terminated by 0x0d 0x0a CR amp LF Response T 01224 r n Z COMMAND 0x5A INFORMATIO Example Z r n Description Reports the latest CO2 measurement in ppm Syntax ASCII Character Z terminated by 0x0d 0x0a CR amp LF Response Z 00512 r n Q COMMAND 0x51 INFORMATIO Example Qirin Description Reports the latest measurement fields as defined by the most recent M command Syntax ASCII Character Q terminated by 0x0d 0x0a CR amp LF Response H 12345 T 12345 Z 00010 r n Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential responsibility is assumed by GSS Ltd for its use Rev B 12 13 Release www gassensing co uk GSS Ltd 2011 2013
6. is then converted into a concentration reported by the sensor The absorption process is pressure dependant so that a change in pressure will cause a change in the reported gas concentration As the pressure increases the reported gas concentration also increases As the pressure decreases the reported concentration decreases This effect takes place at a molecular level as is common to all NDIR gas sensors In normal use the reading will vary by 0 196 of reading for each mbar change in barometric pressure the sensor are calibrated at 1013mbar Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential responsibility is assumed by GSS Ltd for its use Rev B 12 13 Release www gassensing co uk GSS Ltd 2011 2013 A tc J If the sensor is installed at an elevated altitude the mean barometric pressure will be lower than 1013mbar It is possible to configure the sensor to correct for this effect by setting the altitude when installing This will apply a permanent correction to the output of the sensor depending on the altitude setting selected To apply this correction 1 Select the appropriate code from the table below intermediate values can be interpolated 2 Sendthe S r n tothe sensor where is the code from the table below For example to correct the sensor for permanent installation at 305m elevation send S 8494 r n response S 08494
7. subtract 1000 and divide by 10 For example T 01235 r n Represents 23 5 C NB The temperature and humidity sensor is a factory fit option If it is not fitted the sensor will return T 01000 Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential www gassensing co uk responsibility is assumed by GSS Ltd for its use Rev B 12 13 Release GSS Ltd 2011 2013 AA s J 1 3 3 Humidity Measurement Option The humidity measurement is reported as H r n Where is a five digit number To convert to relative humidity 96 divide by 10 For example H 00551 r n Represents 55 196 RH NB The temperature and humidity sensor is a factory fit option If it is not fitted the sensor will return H 00000 1 3 4 Example of T H and CO When shipped the sensor default output is CO2 only To output temperature humidity and CO send M 4164 r n see Output Fields The output format will have the form H 00345 T 01195 Z 00651 r n This example indicates 34 5 RH 19 5 C and 651ppm CO Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential www gassensing co uk responsibility is assumed by GSS Ltd for its GSS Ltd 2011 2013 use Rev B 12 13 Release 4 J 2 Command Summary For complete details of the commands and their correct usage please refer to the Command Reference
8. 18 8 2 User Options EEPROM Settings c csssssssssssssssssssssssscsseseseeeseseeeseeeseseaeseseaeaeaeaeaeaeaeanees 18 8 2 1 S tting BEPROM 33 5 ore Ateste toto series Amas het AN Lh e cde ame 18 8 2 2 Redding EEPROM I ester t e etes te er rette ra eed ed es e REN 19 8 2 3 EER ROM Settings cette tet Reti diae tbt NT 19 8 2 4 Autocalibration Settings locations 3 7 sess 20 8 2 5 User EEPROM s t eter teet ata metre m basses 20 Command References eos oe det eoe ce et eer ehe dede caca cece ERR e eder ee Dre ne reda nas vue RA 21 AA J1 9 1 ro Everti 21 9 2 Ife PEN 22 9 3 Switching between Modes 2 erre eee terre aerea euer oa aan a pe aaa a E eR ve oe AERE Tu a aegre a Drs 22 9 4 Zeroing and Calibration RE ee me et Rue esl Ee ae 23 9 5 Polling Commands ERSTER I 25 This documentation is provided on an as is basis and no warranty as to its suitability or accuracy for any particular purpose is either made or implied Gas Sensing Solutions Ltd will not accept any claim for damages howsoever arising as a result of use or failure of this information Your statutory rights are not affected This information is not intended for use in any medical appliance device or system in which the failure of the product might reasonably be expected to result in personal injury This document provides preliminary information that may be subject to change without not
9. ambient calibration ie the assumed CO concentration in fresh air send p 10 r n response p 00010 00001 r n send p 11 r n response p 00011 00124 r n 8 2 3 EEPROM Settings Most of the EEPROM settings are two byte values indicated by HI and LO in the variable name in the following table We recommend contacting GSS before altering the default values Location Name Purpose Default Value 0 AHHI Reserved 0 1 ANLO Reserved 0 2 ANSOURCE Reserved 0 3 ACINITHI Autocalibration Preload This preloads the 87 autocalibration timer so that the first autocalibration occurs after a shorter time 4 ACINITLO Low byte of above 192 5 ACHI Autocalibration Interval Sets the time interval 94 between autocalibrations 6 ACLO Low byte of above 128 7 ACONOFF Switches Autocalibration ON OFF 0 8 ACPPMHI Autocalibration Background Concentration This 1 determines what background CO level is assumed Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential responsibility is assumed by GSS Ltd for its use Rev B 12 13 Release www gassensing co uk GSS Ltd 2011 2013 A v J for autocalibration 9 ACPPMLO Low byte of above 194 10 AMBHI Ambient Concentration for G command This 1 determines what background CO level is assumed for ambient calibration using the G command 11 AMBLO Low byte of above 194 12 BCHI Buffer clear time This will
10. concentration without any digital filtering Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential responsibility is assumed by GSS Ltd for its use Rev B 12 13 Release www gassensing co uk GSS Ltd 2011 2013 5 J The concentration is reported in the following units Type Range Units Example COZIR A Up to 2 ppm Z 00631 631ppm MISIR COZIR W Up to 65 ppm 10 Z 01200 12000ppm 1 2 SprintIR W COZIR W 100 Up to 100 ppm 100 Z 01500 150000ppm 15 SprintIR W 100 Note that the same units must be used when sending concentration information to the sensor for example the X command and the F command If in doubt the Command see below will indicate what multiplier should be applied to the Z output to convert to ppm Z 00842 z 00765 Sample output from a sensor with factory Z 00842 z 00738 settings Z 00842 z 00875 008 58 This is a COZIR A so the reported CO reading Z 0084 008t is 842ppm Z 0084 00839 2 2z 2z Z 00842 2 amp 2 2 2 To The second figure shows the instantaneous z 00850 mieu CO reading z 00875 See Digital Filter for more details Z 00804 Z 0084 Z 0084 Z 0084 Z 0084 Note that all output from the sensor has a leading space 1 3 2 Temperature Measurement Option The temperature measurement is reported as T r n where is a five digit number To convert to C
11. 7 Background Concentration Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential responsibility is assumed by GSS Ltd for its use Rev B 12 13 Release www gassensing co uk GSS Ltd 2011 2013 AA 5 J The background concentration depends somewhat on the area the sensor is installed Typically a figure between 400ppm and 450ppm is used The factory default is 400ppm To set this send P 8 x r n P 9 y r n where x and y depend on the concentration you want to set Concentration X Y 380 1 124 400 1 144 425 1 169 450 1 194 This is stored as a two byte value the high byte being in location 8 and the low byte in location 9 The value represents the concentration To calculate other values x int concentration 256 y the remainder after dividing concentration 256 7 Altitude Compensation Important This feature was introduced in sensors manufactured after July 2013 using firmware version AL17 or higher The firmware version can be identified by sending the Y or command Altitude compensation applies a permanent correction to the sensor response so should only be used when it is known that the sensor will be operating at altitude permanently NDIR gas sensors such as the COZIR SprintlR and MISIR family of sensors detect the concentration of gas by measuring the degree of light absorption by the gas analyte The degree of light absorption
12. 92 r n S 08192 r n See Span Calibration calibration value s r n Return the span s r n s 08192 r n See Span Calibration calibration value T r n Return the most T r n T 01225 r n 22 5 C in the example recent temperature Temperature sensing is a measurement factory fit option U r n Zero point U r n U 33000 r n See Zero Point Calibration calibration using nitrogen u HHH r n Manual setting of u 32997 r n u 32997 r n See Zero Point Calibration the zero point X HHHH r n Zero point setting X 2000 r n X 32997 r n See Zero Point Calibration using a known gas calibration Y r n Return firmware Y r n Returns two lines See Command Reference version and sensor serial number Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential www gassensing co uk responsibility is assumed by GSS Ltd for its use Rev B 12 13 Release GSS Ltd 2011 2013 AA 8 J Command Use Example Response Comments Z r n Return the most Z r n Z 01521 r n 1521ppm in the example recent CO2 measurement H H 4 r n Autocalibration 9 1 0 8 0 r n 1 08 0 r n See Autocalibration for configuration details A r n Return the A r n 00100 r n Multiply by 100 in the multiplier required example to convert the Z output to ppm r n Return r n See the Command configuration Reference for details information All communications are in ASCII an
13. Requirements for Auto calibration Exposure to Fresh Air The sensor must see fresh air at least once during the auto calibration period You do not need to know when the fresh air will be sensed just that it will be sensed at some point during the period Continuously Powered The auto calibration information is deleted when the sensor is switched off This ensures that each installation is unaffected by any previous history of the sensor For auto calibration to function it must be power on for the whole of the auto calibration period 6 3 Setting the Auto Calibration Parameters Three parameters are required to enable the auto calibration routine Auto Calibration Interval This determines how often the auto calibration takes place Background Concentration Typically 400 450ppm This is the level the sensor will use as background Initial Auto calibration Interval It is possible for the first auto calibration to take place more quickly than the regular auto calibration event This can be useful to stabilize quickly after installation Note that the autocalibration timers are reset when the power to the sensor is interrupted On power on the sensor will always time an initial autocalibration interval first then settle into the regular autocalibration cycle The regular autocalibration timer is reset automatically if the user calibrates the sensor using the U G X F or u commands Information supplied by GSS Ltd is believed to be a
14. Response 00001 r r this number is variable 9 3 Switching between Modes For discussion of different modes of operation see the section Operating Modes Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential responsibility is assumed by GSS Ltd for its use Rev B 12 13 Release www gassensing co uk GSS Ltd 2011 2013 z J K COMMAND 0x4B USER CONFIGURATION Example K 1 Description Switches the sensor between the operating modes Syntax ASCII character K SPACE followed by the mode number terminated by 0x0d 0x0a CR amp LF Response K 1 r n the number mirrors the input value 9 4 Zeroing and Calibration See examples of each of the zero and calibration commands in the following section U COMMAND 0x55 CALIBRATION USE WITH CAR Example U r n Description Calibrates the zero point assuming the sensor is in Oppm COs Syntax ASCII Character U terminated by 0x0d 0x0a CR amp LF Response U 32767 r n the number is variable G COMMAND 0x47 CALIBRATION USE WITH CAR Example G r n Description Calibrates the zero point assuming the sensor is in 400ppm CO Syntax ASCII character G Response G 33000 r n the number is variable F COMMAND 0x46 CALIBRATION USE WITH CARE Example F 410 390 r n Description Calibrates the zero point using a known reading and known CO concentration Syntax ASCII character F th
15. WN U A 9 COZIR Sensor User s Guide COZIR SprintIR and MISIR sensors Serial Format and Connection serosa dde eae eter te erba enini edo etae ESA AANS et ano SENEESE 3 1 1 Cotinie CtioD iine REPRE P REU RO A dasedeekiecbeases 3 1 2 Serial Connec NON sorire reana N en dr ee e eer re xen ee rendere e uer ee rere Re PR dette ere res 3 1 3 Reading Format sempe a OE Gee SE nU 4 1 3 1 CO MEASUPEMENL occ eecccccccccccceeceececueceececeueuscecucecsuucueeseceueuueeceeesseuueesecuueeueeeueeeueueneeseaas 4 1 3 2 Temperature Measurement Option ccccccccssccceessececeesseceeeeseeeceeaeeeeseseeeeeeseeeeseees 5 1 3 3 Humidity Measurement Option esses eene 6 1 3 4 Example Of T H and CO 5 ene Re er a EE SAN EEEE SA TREE OVE ESAE RTOS 6 ero nies nincemcc m X 7 Operating Modes Re i Tite nd esee nn 8 3 1 Mode 0 Command Mode ccsssscccssssececeesnececsesnececseseeeceeaeeecseaeeecseaeeeseeaeeecsequeeeeeeneeeesees 8 3 2 Mode 1 Streaming Mode sss nnne enne en nena sans sss ensi a K aiai siat 8 3 3 Mode 2 Polling Mode 53 ei e eei ect aerae na aee ae Rin qux ea c sao rav Ru o 9 O tput Fields 5 5 e eem EU S 10 Zero Point CaliDratiOn z 2 eet eee eric oie era et no eie ee ra dag a ex ee ee ra TRE gna Geli 11 5 1 Zero in a known gas concentration recommended essere 11 5 2 Zero in euh EE 11 5 3 Ze
16. ccurate and reliable However no Confidential responsibility is assumed by GSS Ltd for its use Rev B 12 13 Release www gassensing co uk GSS Ltd 2011 2013 i J1 6 4 Autocalibration Intervals The autocalibration intervals are set using the command This command allows the autocalibration periods to be set interrogated or disabled To set the autocalibration intervals the command structure is 9 initialinterval regularinterval r n Where both the initial interval and regular interval are given in days Both must be entered with a decimal point and one figure after the decimal point For example send 1 0 8 0 r n response 1 0 8 0 r n Will set the autocalibration interval to 8 days and the initial interval to 1 day Note that there is a space between the and the first number and a space between the two numbers In hex the example above reads 40 20 31 2E 30 20 38 2E 30 OD OA 6 5 Readthe Autocalibration Settings To determine the current autocalibration settings send r n response 1 0 8 0 r n If the autocalibration is enabled the sensor will respond with the format above showing the initial and regular autocalibration intervals If the autocalibration is disabled the sensor will repond with send r n response O r n 6 6 Disable Autocalibration To disable the autocalibration send O r n response O r n ie followed by a space followed by a zero terminated with OxOd OxOa 6
17. clear any incomplete 0 commands from the serial buffer after a fixed period of inactivity The time is in half second increments 13 BCLO Low byte of above 8 200 231 User EEPROM 255 8 2 4 Autocalibration Settings locations 3 7 These are included now to maintain compatibility with previous firmware versions GSS recommends using the command to set autocalibration timings 8 2 5 User EEPROM Locations 200 to 231 can be used to store user values Each location is a single byte These locations are not used by the sensor Eg to store the number 42 in the first user EEPROM location send P 200 42 r n response P 00200 00042 r n and to read it send p 200 r n response p 00200 00042 r n Note that the EEPROM is only guaranteed for 100 000 write cycles Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential responsibility is assumed by GSS Ltd for its use Rev B 12 13 Release www gassensing co uk GSS Ltd 2011 2013 fr J 9 Command Reference This gives the complete command set for the COZIR SprintlR and MISIR sensors and illustrates use of some of the more commonly used options Key points to note are e Inall cases commands are terminated with a carriage return line feed rn e Commands are case sensitive e The commands use all use ASCII characters Each command lists the ASCII letter and includes the hex code for avoidanc
18. d are terminated by carriage return line feed ASCII characters 13 and 10 This document uses the protocol n to indicate the carriage return line feed All responses from the sensor including measurements have a leading space ASCII character 32 The character represents an ASCII representation of a numeric character 0 9 Note that there is a space between the first letter and any parameter For example the X command reads X space 2000 carriage return line feed Note that all settings are stored in non volatile memory so the sensor only has to be configured once It should not be configured every time it is powered up 3 Operating Modes The COZIR SprintIR and MISIR sensors can be operated in three different modes Users can switch between the modes using the K command 3 1 Mode 0 Command Mode This is primarily intended for use when extracting larger chunks of information from the sensor for example using the Y and commands In this mode the sensor is stopped waiting for commands No measurements are made and the sensor will run through a warm up cycle after exiting this command There is no latency in command responses The power consumption is less than 3 5mW as no measurement activity takes place Commands which report measurements or alter the zero point setting are disabled in mode O Mode 0 is NOT retained after power cycling The sensor will always power up in streaming or polling mode whichever was
19. e of doubt e Always check for a correct response before sending another command e fa command is unrecognized the sensor will respond with a WARNING This document is provided to give a complete reference of the command set and outputs from the COZIR sensor It is intended for advanced users only If in doubt please contact GSS engineering prior to use 9 1 Customisation A COMMAND 0x41 USER CONFIGURATION Example A 128 r n Description Set the value for the digital filter Syntax ASCII character A SPACE decimal terminated by 0x0d Ox0a CR amp LF Response A 00032 r n a COMMAND 0x61 INFORMATIO Example a r n Description Return the value for the digital filter Syntax ASCII Character a terminated by OxOd 0x0a CR amp LF Response a 00032 r n M COMMAND 0x4D USER CONFIGURATION Example M 212 r n Description Determines which values are going to be returned by the unit Syntax M SPACE followed by an up to 5 digit number each bit of which dictates which item will be returned by the sensor terminated by 0xOd 0x0a CR amp LF Response M 212 r n see Output Fields for details P COMMAND 0x50 USER CONFIGURATION Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential responsibility is assumed by GSS Ltd for its use Rev B 12 13 Release www gassensing co uk GSS Ltd 2011 2013 AA 2 J Example P 10 1 r n Description
20. eading of 400ppm would now be reported as 380ppm 5 5 Zero Point Adjustment The precise zero point can be fine tuned by sending a zero point to the sensor This is not recommended for general use Send the command u r n where isthe new zero point 6 AutoCalibration 6 1 Principle of Operation COZIR sensors are fully calibrated prior to shipping from the factory Over time the zero point of the sensor needs to be calibrated to maintain the long term stability of the sensor In many applications this can happen automatically using the built in auto calibration function This technique can be used in situations in which sensors will be exposed to typical background levels 400 450ppm at least once during the auto calibration period For example many buildings will drop quickly to background CO levels when unoccupied overnight or at weekends The auto calibration function uses the information gathered at these periods to recalibrate Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential responsibility is assumed by GSS Ltd for its use Rev B 12 13 Release www gassensing co uk GSS Ltd 2011 2013 E o o c 9 LI c c w o c o eo N O O One Week gt This recording from a sensor shows a typical one week recording in an office environment The auto calibration function uses the low point circled and uses it to recalibrate the zero point 6 2
21. en a space then the reported gas concentration then a space then the actual gas concentration Response F 33000 r n the numbers are variable X COMMAND 0x58 CALIBRATION USE WITH CAR Example X 1000 r n Description Calibrates the zero point with the sensor in a known concentration of CO Syntax ASCII character X then a space then the gas concentration Response X 33000 r n the number is variable S COMMAND 0x53 CALIBRATION USE WITH CAR Example S 8192 r n Description Set the Altitude Compensation value in EEPROM Syntax ASCII character S SPACE decimal terminated by 0x0d Ox0a CR amp LF Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential responsibility is assumed by GSS Ltd for its use Rev B 12 13 Release www gassensing co uk GSS Ltd 2011 2013 u J Response S 8192 r n the number mirrors the input value s COMMAND 0x73 INFORMATIO Example s r n Description Reports the Altitude Compensation value in EEPROM See Altitude Compensation Syntax ASCII Character s terminated by 0x0d 0x0a CR amp LF Response s 8193 r n u COMMAND 0x75 USE ONLY WITH GSS GUIDANC Example u 32767 r n Description Send a zero set point Syntax ASCII character u SPACE decimal terminated by 0x0d Ox0a CR amp LF Response u 32767 r n NB For advanced use only Contact GSS before using this command There are three varia
22. erter to step up down the voltage and invert the signal Connection to the sensor is via a 10 way 0 1 pitch connector In practice only the first 4 pins are required GND 3V3 Rx and Tx so a 4 way connector can be used Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential www gassensing co uk responsibility is assumed by GSS Ltd for its GSS Ltd 2011 2013 use Rev B 12 13 Release a J A starter kit is available to allow simple interfacing between the sensor and a PC Contact GSS www gassensing co uk for details File Control Setup Measure Analyze Utilities Help 4 29 PM Scope trace showing command sent to the sensor green and sensor response yellow Parameter Value Baud Rate 9600 Data Bits 8 Parity None Stop Bits 1 Format UART normally high Hardware Flow Control None Voltage Voh 3V MISIR Von Vsupply Voltage Vih 3V 5V NB If you connect to the sensor using HyperTerminal you must select the box Send line ends with line feeds under ASCII setup When initially powered the sensor will immediately start to transmit readings see Mode 1 in Operating Modes 1 3 Reading Format 1 3 1 CO Measurement The CO measurement is reported as Z z r n where Z shows the CO concentration after digitally filtering and z shows the instantaneous CO
23. ice The information in this guide is for the use of employees and customers of GSS Ltd only This guide applies to software versions from July 2013 For previous versions please refer to COZIR Software USER s Guide Rev F Conventions In this guide r n Is used to indicate carriage return CR line feed lt LF gt characters 0xOd 0xOa which are required at the end of each string sent to the sensor and are appended to all transmissions from the sensor Z 12345 r n Courier fixed pitch font is used to show commands sent to the sensor and transmissions received from the sensor Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential responsibility is assumed by GSS Ltd for its use Rev B 12 13 Release www gassensing co uk GSS Ltd 2011 2013 8 _ 1 Serial Format and Connection 1 1 Connection Communication to and from the COZIR sensor is via a serial connection Pins are shown looking at the connector of the sensor COZIR A GND N C 3V3 N C Rx N C Tx Zero N C Ambient COZIR W SprintIR lt E ru MISIR 0000 0000 d o Tx x 33 m MO wo 5 3 z Only one GNO connection is required 1 2 Serial Connection The Rx and Tx pins are normally high suitable for direct connection to a UART If the sensor is to be read by a true RS232 device eg a PC it is necessary to pass through a level conv
24. ith some periods of rapidly changing concentrations 8 1 3 Reading the Digital Filter Setting The current setting for the digital filter can be determined by sending a Vr n send a r n response a 00032 r n 8 2 User Options EEPROM Settings Some user settings can be altered in the internal EEPROM These settings can be set by using the parameter setting command P and read using a lower case aan p There are also 32 bytes of user EEPROM storage available 8 2 1 Setting EEPROM To set an EEPROM location send P r n Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential www gassensing co uk responsibility is assumed by GSS Ltd for its GSS Ltd 2011 2013 use Rev B 12 13 Release o J where the first parameter is the address and the second is the value Note that two byte values must be set one byte at a time For example to change the default value of the ambient gas concentration used for ambient calibration ie the assumed CO concentration in fresh air to 380ppm send send P 10 1 r n response P 00010 00001 r n send P 11 124 r n response P 00011 00124 r n 8 2 2 Reading EEPROM To read a parameter value from an EEPROM location send p r n where tt is the address of the parameter Note that two byte values must be read one byte at a time For example to read the value of the ambient gas concentration used for
25. known gas see X command which will give the most accurate zero setting In all cases the best zero is obtained when the gas concentration is stable and the sensor is at a stabilized temperature 5 1 Zero in a known gas concentration recommended Place the sensor in a known gas concentration and allow time for the sensor temperature to stabilize and for the gas to be fully diffused into the sensor Send the command X r n The concentration must be in the same units as the sensor output see Reading Format The sensor will respond with an echo of the command and the new zero point For example to set the zero point in a COZIR A when the sensor is in a known gas concentration of 2000ppm send X 2000 r n response X 32950 r n 5 2 Zeroin Nitrogen Place the sensor in a gas containing no CO2 typically nitrogen and allow time for the sensor temperature to stabilize and for the gas to be fully diffused into the sensor Send the command U r n The sensor will respond with an echo of the command and the new zero point For example send U r n response U 32950 r n 5 3 Zero in Fresh Air assumed to be 400ppm If there is no calibration gas and no nitrogen available the sensor zero point can be set in fresh air The sensor is programmed to assume that fresh air is 400ppm this value is user configurable see User Settings Place the sensor in a fresh air environment and allow time for the sensor temperature to stabi
26. lize and for the fresh air to be fully diffused into the sensor Send the command Gir An The sensor will respond with an echo of the command and the new zero point For example send Gir Mn Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential responsibility is assumed by GSS Ltd for its use Rev B 12 13 Release www gassensing co uk GSS Ltd 2011 2013 A 2 J response G 32950 r n 5 4 Fine Tune the Zero Point If the CO2 concentration and the sensor reported concentration are known the zero point can be adjusted using the known concentration to fine tune the zero point This is similar in operation to the X command see above but can operate on historic data For example if the sensor has been in an environment in which it is know to have been exposed to outside air and the sensor reading is known at that time the zero point can be fine tuned to correct the reading This is typically used to implement automated calibration routines The command takes two parameters separated by a space The first parameter is the reading reported by the sensor The second is the corrected reading Both parameters must be in the same units as the sensor output see Reading Format The sensor will respond with an echo of the command and the new zero point For example send F 400 380 r n response F 32950 r n In this example the sensor zero point would be corrected so that a r
27. nts of the autocalibration configuration command COMMAND 0x40 INFORMATIO Example r n Description Return the autocalibration settings Syntax ASCII character terminated by 0x0d Ox0a CR amp LF Response 1 0 8 0 r n if autocalibration is enabled O r n if autocalibration is disabled COMMAND 0x40 CALIBRATION USE WITH CAR Example O r n Description Switch off the autocalibration function Syntax ASCII character followed by a SPACE followed by a zero terminated by OxOd 0x0a CR amp LF Response eg O r n COMMAND 0x40 CALIBRATION USE WITH CAR Example 1 0 8 0 r n Description Set the Autocalibration timing Syntax See Autocalibration section Response 1 0 8 0 r n the number mirrors the input value Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential responsibility is assumed by GSS Ltd for its use Rev B 12 13 Release www gassensing co uk GSS Ltd 2011 2013 3 J 9 5 Polling Commands H COMMAND 0x48 INFORMATIO Example H r n Description Reports the humidity measurement from the temperature and humidity sensor if fitted Divide by 10 to get the RH Syntax ASCII Character H terminated by 0x0d 0x0a CR amp LF Response H 00551 r n T COMMAND 0x54 INFORMATIO Example T r n Description Reports the humidity measurement from the temperature and humidity sensor
28. r n Altitude ft Altitude m Barometric Pressure mbar Code 1000 305 1050 7889 0 0 1013 8192 1000 305 976 8495 2000 610 942 8774 3000 915 908 9052 4000 1219 875 9322 5000 1524 843 9585 The current setting can be determined by sending a lower case s send s r n response s 08494 r n Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential www gassensing co uk responsibility is assumed by GSS Ltd for its GSS Ltd 2011 2013 use Rev B 12 13 Release v J 8 User Settings 8 1 Digital Filter 8 1 1 Customising the Sensor Response The CO2 measurement is passed through a digital filter to condition the signal The characteristics of the filter can be altered by the user to tune the sensor performance to specific applications The filter operates as a low pass filter increasing the filter parameter reduces measurement noise but slows the response There is a tradeoff between noise resolution and speed of response The filter can be set to a value between 1 and 65535 Settings larger than 64 are not recommended for normal use A low value will result in the fastest response to changes in gas concentration a high value will result in a slower response Note that the response is also determined by the diffusion rate into the sensor The default setting is 32 This chart shows the effect of changing the filter setting Sensor Noise vs Filter Setting
29. ro in Fresh Air assumed to be 400ppm sssessssssesseeeeee enne enne enne enne 11 5 4 Fine Turie the Zero POlnt uiie rie reitera coe eee eeu oae eade e nena aee eua dee mea ae ger adeo 12 5 5 Zero Point Adjustment ccccccssssscsccececeesssssansececeesesssusausececeesesssasaesececeeseaesaeaesecueseseauanaeees 12 AutoCalibration x d aee tenir ee col ere dee re eie na eaque ede ere race ree de eu na ena Du elts 12 6 1 Principle of Operation e m sa RE T eei ed reca ie Ro es 12 6 2 Requirements for Auto calibration esses eene nennen nenne nennen ener an 13 6 3 Setting the Auto Calibration Parameters sse enne nins 13 6 4 Autocalibration Intervals i eene ete nahen nae ee rie rena eau ree ra oi eara ea no aida 14 6 5 Read the Autocalibration Settings eese ener nnne nnns nennen an 14 6 6 Disable Autocalibratiori 2 nete ec ectetur eel e nena cae A S eeu eee geraden 14 6 7 Background Concentrations Ack soot oet tn ea ee teen 14 Altit de CompersatiOon cert ce retener teet redet vertatur edu vetet ecd Ee Det 15 User Settlhgs i scooter ette etta t E 17 8 1 Digital Filters yt eoe tet me et ere tur ee FERE ee 17 8 1 1 Customising the Sensor Response isses nennen enne nnne nennen nn assess nean 17 8 1 2 Setting the Digital Filter x io otto e ete redet na ops e ERR e dun 18 8 1 3 Reading the Digital Filter Setting necte i anne r E E EER a nt
30. s a value related to the normalized LED signal strength Sensor Temperature V 128 Reports a value which varies inversely with the sensor unfiltered temperature Temperature T 64 Reports the temperature output of the Temperature and Humidity Sensor if Fitted LED Signal digitally o 32 Reports a value which gives an indication of the LED signal filtered strength smoothed LED Signal unfiltered Oo 16 Reports a value which gives an indication of the LED signal strength Sensor Temperature V 8 Reports a value which varies inversely with the sensor filtered temperature smoothed CO2 Output Digitally Z 4 Digitally filtered CO2 reading Filtered CO2 Output not z 2 Instantaneous CO2 reading filtered Note that most fields are for advanced use only and require specific guidance from GSS engineering for their correct interpretation and use Measurement field are indicated in bold For example to output the temperature humidity and CO2 measurements send M 4164 r n Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential responsibility is assumed by GSS Ltd for its use Rev B 12 13 Release www gassensing co uk GSS Ltd 2011 2013 n J The output string will then be H 12345 T 12345 Z 00010 r n 5 Zero Point Calibration There are a several methods to calibrate the zero point of the sensor The recommended method is zero point calibration in a
31. the most recently used 3 2 Mode1 Streaming Mode This is the factory default Measurements are reported twice per second Commands are processed when received except during measurement activity so there may be a time delay of up to 100mS in Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential responsibility is assumed by GSS Ltd for its use Rev B 12 13 Release www gassensing co uk GSS Ltd 2011 2013 o J responding to commands The power consumption is 3 5mW assuming one field of information is transmitted and there is no temperature and humidity sensor 3 3 Mode 2 Polling Mode In polling mode the sensor only reports readings when requested The measurement cycle continues in the background but the output stream is suppressed The power consumption depends on the frequency of polling but is approximately the same as the streaming mode power consumption Note that the sensor will power up in the mode last used If it was last used in KO mode it will power up in either K1 or K2 mode depending on which was most recently used In Polling Mode measurements can be accessed using the polling commands H L Q T and Z see Command Reference Information supplied by GSS Ltd is believed to be accurate and reliable However no Confidential responsibility is assumed by GSS Ltd for its use Rev B 12 13 Release www gassensing co uk GSS Ltd 2011 2013 o
Download Pdf Manuals
Related Search