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DrDAQ User Guide

1. 43 DrDAQ User Guide Arguments min_value The minimum value that the channel can take max_value The maximum value that the channel can take places The number of decimal places divider The number that values should be divided by to give real numbers is_fast TRUE 1 if the channel is capable of providing rapidly changing signals channel This specifies the channel to return details for Returns 1 if successful 0 if unsuccessful 3 2 3 Programming support 3 2 3 1 C C programs can access all versions of the driver If drdaqw h is included in a C program the PREF1 macro expands to extern C this disables name decoration as Microsoft calls it and enables C routines to make calls to the driver routines using C headers See the C examples for sections of C code to interface with the driver 3 2 3 2 C The C example program is a generic windows application ie it does not use Borland AppExpert or Microsoft AppWizard To compile the program create a new project for an Application containing the following files drdaqtes c drdagqtes rc either drdaq32 11ib Borland applications or drdaqms lib Microsoft Visual C applications The following files must be in the same directory drdaqtes rch drdaqw h drdaq32 d11 all applications 3 2 3 3 Delphi drdaq dpr is a complete program that demonstrates the use of DrDAQ The file dardaqfm inc contains a set of procedure prototypes that you can
2. DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Software information 38 Retur ns none 3 2 2 9 drdaq_get_value_and_time PR sa mple_time EF 1 void PREF2 drdaq_get_value_and_time short channel unsigned long short value This routine reads the current value of one channel from the currently selected DrDAQ and the time in microticks at which the reading was taken Depending on your computer it will take approx 200 us to take one reading Value scaled using the current scaling for this channel Arguments channel the channel number is 1 through to 9 see channel scaling for more information sample_time jg the time in microticks for the reading There are microticks per hour or 1 193 046 per second The sample time will therefore wrap around once an hour pve value a pointer to Returns none 3 2 2 10 drdaq_set_trigger PRI EF1 void PREF2 drdaq_set_trigger short short Short short Short short short enabled auto_trigger auto_ms channel dir threshold delay This routine defines a trigger event for the next block operation and specifies the delay between the trigger event and the start of collecting the data block Note that the delay can b e negative for pre trigger Copyright 2005 Pico Technology Limited All
3. A general DrDAQ sensor can be broken down into blocks Signal input Ground Auto Detect P 2 8 2 Powering the sensor The definition of a sensor is Device giving signal for detection or measurement of a physical property to which it responds The sensor properties must be known before work can begin in designing some way of interfacing it to the DrDAQ Sensor scaling There are two types of sensor Active Sensors These sensors require power Excitation from an external source to generate an output signal examples of active sensors include Property Sensor Output Temperature Silicon Voltage Current RTD Resistance Thermistor Resistance Force Pressure Strain Gauge Resistance Acceleration Accelerometer Capacitance Humidity Capacitor Resistance Light LDR Resistance Position LVDT AC Voltage Copyright 2005 Pico Technology Limited All rights reserved DRDAQ044 2 25 DrDAQ User Guide 2 8 3 Passive Sensors These do not require any power to generate an output typical examples are Property Sensor Output Temperature Thermocouple Voltage Force pressure Piezoelectric Voltage Position Variable Resistor Resistance Light Intensity Photodiode Current When selecting a sensor for an application you should consider the following 1 Is the sensor Active or Passive if Active then can it be powered by the
4. DrDAQ Data Logger User guide Copyright 2005 Pico Technology Limited All rights reserved DRDAQ044 2 l DrDAQ User Guide Table of Contents T introduction sssccscscosssooonoomaa raana anaa AARAA OPAO NAAA PAA ENAA APAA AAA ENANA RARONAAPARAAN 2 eS a A E T E E ioe 2 2 Safety warning eeeeeeeeeeeeeerrerrnnrnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnne 2 3 Legal information ssssnnnrnnnrrrrsrnnnnnnnnnnrnnnnnnnnnnnnnnnnnnnnnnnennnnnnn nnnm 3 2 Product informatio sdisiisessisssscssecncaasansenscnseaasansmseeseesasannensemeemesaenmeeemeesesaanensanin 4 1 Specifications ssssss1s1111111trrrrrrrrerrrtrerrrnrnnrrrrreeereereeeeeeeeereeeeeeeene 4 2 Connecting to the PC eeeeeeerererrrernnnrnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn nnn 4 3 Connections sssssssssssssnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn nnmnnn nananana 5 4 Channel scaling sssssssnnnnnnnrsnennnnnnnnnnnesnnnnnnnnnnennnnnnnnnnnnnnnnnnnnnnnnnnne 6 5 Getting started with PLW e sereseressrresreresrusrrnnrrnnnrenusrnnnrnnnnrnnnrnnnnnnnnnna 6 6 Getting started with PicOSCOPe eee essrernsserrnnnrrrnnnnrrnnnnnrrnnnnrernnnnne 7 7 External Sensors isi issesscisesescceecanscseeaesiesecneseescceesscvedeedessedeenecsedessecsedesees 11 8 Making your OWN SENSOSS 1 ccceeeeeeeeeeeeeeeeeeeseneeeeeeseeneeeessseeeeeesseneeeess 23 3 Software informatio
5. total block time is correct if the number of samples is important collect the same number of samples then allow for the fact that they took longer to collect 3 2 2 12 drdaq_get_values PREF 1 unsigned long PREF2 drdaq_get_values short HUGE values unsigned long no_of_values This routine reads in a block of readings at intervals and from channels specified in the most recent drdaq_set_interval call Arguments values a buffer for the readings The readings are scaled using the currently selected scaling for each channel If multiple channels are selected the readings for the channels are interleaved For example with channels 1 3 and 8 the readings in the buffer would be 1 3 8 1 3 8 1 3 8 no_of_values the number of readings to collect Returns the actual time for the block or zero if a key is pressed If a key is pressed while collecting the routine will return immediately The return value will be zero if a key was pressed and the total time in microseconds if a block was successfully collected Copyright 2005 Pico Technology Limited All rights reserved DRDAQ044 2 41 DrDAQ User Guide 3 2 2 13 drdaq_get_times_and_values PREF1 unsigned long PREF2 drdaq_get_times_and_values long HUGE times short HUGE values unsigned long no_of_values This routine takes a block of readings at nominal intervals speci
6. DD100 Temperature Sensor DD100 Temperature Sensor High accuracy general purpose temperature sensor with a 2 metre lead Suitable for air surface or liquid measurements Range 10 C to 105 C Resolution at 25 C 0 1 C Accuracy at 25 C 0 3 C DDO11 pH Electrode DD011 pH Electrode lt pime pH is measured using a standard electrode with a BNC connector Pico supplies a robust epoxy bodied pH electrode ideal for educational use It covers the full 0 to 14pH range DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Product information 12 Pico supplies two different makes of pH electrode Both operate in exactly the same way and are interchangeable in use Before using your electrode please remove either the protective cap top photograph or storage bottle bottom photograph Size 12 x 120 mm Operating temperature 0 to 60 C Resolution 0 02 pH Using DrDAQ with pH Electrodes The pH input on DrDAQ is a very high impedance input that is suitable for use with any standard pH electrode For most applications no calibration is required just plug in an electrode and measure If however you require very accurate pH measurements then you should calibrate the probe before use see below If you are using a pH probe and not getting the results you expect then the most probable cause is a defective pH electrode If cared for properly pH electrodes will last for a number of
7. 12 Push the bare ends of the leads into the holes in the back of the terminal block There should be one lead in each hole 13 Tighten the screws in the terminal block and check that the leads are held firmly in place Do not overtighten the screws 14 Put the lid back on to the EL029 Make sure it is on the right way round 15 Tighten the fixing screw being careful not to overtighten it 16 Check the operation of the external switch Connect up the EL029 and make sure that PicoScope or PicoLog shows near to 100 when your external switch is open and 0 when it is closed DD101 Humidity Sensor DD101 Humidity Sensor DD101 Humidity Sensor is used to measure humidity by a non condensing technique It has a short response time and plugs into the external sensor connections of DrDAQ Size 72 x 45 x 28 mm Operating range 20 90 Relative Humidity Overall accuracy Reading or 10 Operating temperature 0 60 C Resolution 0 2 Relative Humidity Minimum response time 60 seconds with vigorous air movement Maximum response time 60 minutes in still air Caution Do not allow the DD101 sensor to become wet The DD101 is a non condensing sensor and liquid entering the case including condensation may damage it The DD101 may be connected to either Ext1 or Ext2 on DrDAQ Tips for use of DD101 Humidity Sensors The sensor responds to humidity changes more slowly in still air If you need to increase the response time then incre
8. DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Software information 42 Returns none The return value is the length of the string placed in str it will be zero if the line or port are invalid 3 2 2 15 drdaq_get_channel_text PREF1 short PREF2 drdaq_get_channel_text char Six short channel short field This routine returns one of five text strings depending on the value of field Arguments str text buffer for returned string channel line number 1 9 see channel scaling field field number 0 channel name 1 short channel name 5 chars max 2 scaling name for currently selected scaling 3 short scaling name 5 chars max 4 units for currently selected scaling Returns 1 if successful 0 if unsuccessful The return value is the length of the string placed in str it will be zero if the line or port are invalid 3 2 2 16 drdaq_get_channel_info PREF1 short PREF2 drdaq_get_channel_info short min_value short max_value short places short divider short is_fast short channel This procedure returns as set of information about the currently selected scaling for the specified channel If a parameter is not required you can pass a null pointer to the routine Copyright 2005 Pico Technology Limited All rights reserved DRDAQO044 2
9. DrDAQ 2 What is the output of the sensor can the sensor be plugged directly into the DrDAQ 3 Is the sensor already available on the DrDAQ or are there more suitable sensors out there Why re invent the wheel The power available from the parallel port will vary from PC to PC however will typically be 2 mA at 3 5 V Because the voltage varies this needs to be taken into account when designing a sensor it should be essential that the sensor can be used with DrDAQ on all machines In order to guarantee a consistant power supply to your sensor it is necessary to assume the worst i e the minimum voltage according to the DrDAQ specification could be 3 V See the circuit below for an example of a simple power supply circuit Power supply example VCC is drawn from Pin 4 on the DrDAQ socket GND is connected to Pin 2 on the DrDAQ socket REF25 is a2 5 V reference Scaling Sensor Scaling Software It is necessary to create a scaling file so that the software can extract details about the sensor Details on creating scaling files can be found on the DrDAQ Scaling Files DDS topic Scaling in software also provides an opportunity to perform a calibration on the sensor this can compensate for any manufacturing irregularities Sensor Scaling Hardware With both these types of sensors it is essential that the DrDAQ displays an accurate representation of the property to be measured there are many factors to take into acco
10. If you suspect that the pH input on DrDAQ may be defective then short out the BNC connector using a terminator plug or paper clip The reading on the screen should be pH7 0 5 if not then the most likely reason is that someone has calibrated the probe incorrectly Select File New Settings from PicoLog to delete the user calibration and return to the default calibration If the reading is still wrong then contact technical support Calibrating for accurate pH measurements As described above calibration is only required when accurate better than 0 5pH measurements are required Calibration should be performed just before the measurements are made User calibration information is stored separately in PicoScope Copyright 2005 Pico Technology Limited All rights reserved DRDAQ044 2 13 DrDAQ User Guide and PicoLog so if you wish to measure pH accurately with both programs 2 calibrations will be required To calibrate a pH electrode you will require at least 2 pH buffers 9H4 pH7 and pH10 buffers are widely available Calibration should be performed with the ambient temperature close to 25 C A container of clean water is also required to wash the electrode before moving it from one buffer to another 1 Connect the pH electrode to DrDAQ and display pH using either PicoScope or PicoLog depending on which program you are calibrating for 2 Place the electrode in the first solution and wait for at least 30 seconds f
11. Limited registered in the United Kingdom and other countries Pico Technology acknowledges the following product names as trademarks of their respective owners Windows Excel Visual Basic LabVIEW Agilent VEE HP VEE Delphi DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Product information 4 2 1 2 2 Product information Specifications General specifications Number of input channels 7 internal 2 external Typical sampling rate 15 000 samples per second measured on 100 MHz Pentium Input overvoltage protection 30 V Digital output voltage typically 3 5 V depending on PC and load Digital output impedance approx 1 3 kQ depending on PC Output connector 25 way male D type connects to PC parallel port Internal sensor specifications Channel Range Resolution Accuracy Sound waveform 100 0 2 Not calibrated Sound level 55 to 100 1 dBA 5 dBA dBA Voltage Oto5V 5mvV 3 of FSD Resistance Oto 1 MQ 0 1 KQ at10 2 at 100k kQ pH 0 to 14 0 02 pH Calibration dependent Temperature 10 C to 0 1 C at 25 C 0 3 C at 25 C 105 C Light 0 to 100 0 1 Not calibrated Connecting to the PC DrDAQ is connected to the parallel port of your computer Parallel ports can be easily identified as they are a female 25 way connector It is common for parallel ports to be labelled as printer ports or simply LPT It is pos
12. for LPT2 and so on DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Software information 36 Returns TRUE if successful If it is not successful you can call drdaq_get_unit info to find out why it failed 3 2 2 3 drdaq_apply_fix PREF1 void PREF2 drdag_apply_fix short fix no short value This procedure is used to modify the behaviour of the driver Arguments Fix n the attribute to modify 0 Temperature unit 1 pH compensation value the new value for the attribute If fix_no 0 set temperature unit 0 Celsius 1 Fahrenheit 2 kelvin If fix_no 1 select pH compensation 0 Internal 1 External 1 2 External 2 3 None 4 Auto select between External 1 and Internal Returns none 3 2 2 4 drdaq_close_unit PREF 1 void PREF2 draag close unit short port This routine closes the DRDAQ unit on the specified port Arguments port the number of the parallel port Returns none 3 2 2 5 drdaq_set_unit PREF1 short PREF2 drdaq_set_unit short port This routine is used to select the unit to use for subsequent operations It is only necessary to use this function if you wish to have more than one unit open at the same time Copyright 2005 Pico Technology Limited All rights reserved DRDAQ044 2
13. gives 7 65 For some sensors there is more than one possible scaling available You can call drdaq_get_scalings to get a list of valid scaling codes then call drdaq_set_scaling to select one of them Once selected drdaq_ get channel text and drdaq get channel info will return full information about the selected scaling If you do not use drdaq_set_scaling the driver will automatically select the first available scaling for each channel DrDAQ scaling files can be used to supplement the scalings built into the driver Several DDS files may be used and these must be placed in the current working directory where the DrDAQ software is installed normally C The filename must conform to the DOS format of eight characters followed by the dds extension The total number of sets of scaling data in all the files used must not exceed 99 Each scaling file may contain more than one set of scaling data Each scaling must have a unique scaling number contained in the Scale section heading Numbers above Copyright 2005 Pico Technology Limited All rights reserved DRDAQ044 2 29 DrDAQ User Guide 100 are reserved for Pico Technology customers should use numbers below 100 for custom scaling A typical entry from a DDS file is shown below Scalel100 Resistor 330 LongName Temperatur ShortName TempC Units C inValue 40 axValue 120 OutOfRange 0 Places 1 ethod 0 IsFast Yes NoOfPoints 32 Rawl 2 385 Scaled1 30 R
14. include into your own programs DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Software information 44 3 2 3 4 3 2 3 5 3 2 3 6 Visual Basic The DRIVERS sub directory contains the following files DRDAQ32 VBP DRDAQ32 BAS DRDAQ32 FRM Excel The easiest way to get data into Excel is to use the Picolog program However you can also write an Excel macro which calls drdagxx d11 to read in a set of data values The Excel Macro language is similar to Visual Basic The example drdaqxx XLS reads in 20 values from channels 1 and 2 one per second and assigns them to cells A1 B20 Note it is usually necessary to copy the DLL file to your directory Excel 97 example The file DrDaq97 xls contains a more advanced example for Excel 97 The default setting for the example takes 100 readings from the light sound and temperature channels and displays the results in separate cells The following can be configured via the settings button Port number Channels to take readings from No of readings to be taken Continuous readings on off Displayed in a single cell only LED on off Set up a trigger Target time to collect number of samples To stop the application running press the Stop button To run the application press the Run button To clear the screen of data press the Clear button LabVIEW The routines described here were tested u
15. lookup points Rawl 2 385 Raw value for the first point in the look up table The value is in V volts and should not be greater than 2 500 V Scaledl 30 Scaled value for the first point in the look up table The units are specified by the units parameter 2 8 5 Calibration Calibration with DrDAQ and its sensors is achieved with Scaling Files Calibration involves measuring a known value such as the temperature of boiling water or the resitance of a known resistor or the values shown by a calibrated sensor then converting these values into the units you need Linear Y x Single Point Calibration When calibrating a sensor with a linear response curve it may only be necessary to perform a Single Point Calibration This only occurs in one circumstance One pair of values is known for example on the DrDAQ oxygen sensor The sensor is known to output OmV at 0 oxygen content Therefore we only need to find one other pair of values All we are doing here is changing the gradient of the response curve See the Oxygen Sensor description for a full example Two Point Calibration A two point calibration should always be carried out if possible since it is the most accurate calibration method for a sensor with a linear response curve It is important that the readings are taken for both extremes of the sensor s operating input range to ensure accuracy For example A temperature sensor has an input range of 200 C to 200
16. measuring the normal atmosphere then this reading is currently displayed on the PicoLog monitor view Complete the table above with this value and follow the instructions below Select the Settings Input channels menu item and click OK Select the Oxygen sensor from the list then click Edit Click on Options then Scaling From the drop down Scaling method menu select Table lookup From the look up table you completed above enter these values in the following format replace 19 9 with whichever value you read from the monitor view 00 19 9 20 9 Separate the values above with spaces 6 Close all of the dialogs by clicking OK in each one ORUN PicoLog s monitor view should now display 20 9 or very close for the oxygen content in air If so you ve successfully calibrated your DrDAQ oxygen sensor Looking After the Oxygen Sensor Ensure that the storage temperature and humidity ranges in the specification are not exceeded The sensor is not designed for use in liquids and using it in this way will damage the sensor The sensor has a lifetime of 900 000 O2 hrs in air at sea level the sensor will operate effectively for over 4 years this will decrease if the sensor is exposed to high oxygen concentrations for prolonged periods The lifetime of the sensor can be affected by exceeding the storage operating ranges and exposure to some gaseous chemicals in high concentrations please avoid the following sodium hydroxide ace
17. work with PicoLog and calibrating it using the oxygen in the atmosphere as a reference point calibration is necessary to use the sensor with 3 accuracy If you have not yet set up DrDAQ with PicoLog do so using the PicoLog help file before continuing below Connect the Oxygen Sensor to the socket labelled Ext1 on the DrDAQ unit From the File menu select New settings Click OK Check that DrDAQ is selected as the Converter type and that the correct port is selected Usually LPT1 Click OK Click Add Under Channel select External 1 The Scaling type will automatically change to oxygen Go back to the main monitor view by clicking OK on the two dialog boxes AUN o Nog A DrDAQ should be receiving information from the oxygen sensor The sensor should be calibrated using the procedure below DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Product information 22 Calibrating the oxygen sensor Both PicoLog and PicoScope provide the facility to enter scaling look up tables These instructions will concentrate on doing so in PicoLog for instructions on Custom Ranges in PicoScope see the PicoScope help file This is the information we have so far Raw Values after built in Calibrated Values Scaling File known to be true 0 0 20 9 Known oxygen in air at sea level Only one more value is needed to complete the look up table if you are
18. years see the instructions supplied with the electrode If they are not stored properly then they will be destroyed in a few weeks Trying to calibrate out errors from a defective probe will not work and may increase errors further pH measurement and temperature calibration The output from a pH electrode is proportional to absolute temperature kelvin A temperature difference of 10 C will cause the probe output to change by approximately 4 This is a major source of error with most pH meters and data loggers To minimise these errors DrDAQ uses the internal temperature sensor to compensate for temperature changes Testing pH Electrodes The best way to test a pH electrode is to use pH buffers pH4 pH7 and pH10 buffers are widely available If you do not have any pH buffers then distilled de ionised water will have a pH near 7 some still mineral water bottles have the typical pH printed on the label Most fizzy cola drinks have a pH in the 2 5 to 3 range With the pH electrode connected to DrDAQ display the pH channel using PicoLog Measure the pH of each buffer in turn Allow 30 seconds for the reading to stabilise and be sure to wash the electrode in clean water before swapping solutions If the pH measured is within 1pH of the expected value then you can be fairly sure the electrode is working correctly If the readings are wrong then the electrode is probably defective replacement electrodes are available from Pico Technology
19. 37 DrDAQ User Guide Arguments port the parallel port number as outlined in drdaq open unit Returns TRUE if successful FALSE if a unit is not open on that port 3 2 2 6 drdaq_set_do PREF 1 void PR EF2 drdaq_set_do short do_value This routine sets the state of the digital output pin for the currently selected DrDAQ unit Any non zero value will turn the digital output on zero will turn it off Arguments do_value 1 turns the digital output on 0 turns the digital output off Returns none 3 2 2 7 drdaq_set_led PREF 1 void PR EF2 drdaq_set_led short do_value This routine sets the state of the LED for the currently selected DrDAQ unit Any non zero value will turn the LED on zero will turn it off Arguments do_value 1 turns the LED on O turns the LED off Returns none 3 2 2 8 drdaq_get_value PREF 1 short PR EF2 drdagq_get_value short channel This routine reads the current value of one channel from the currently selected DrDAQ Depending on your computer it will take approx 200us to take one reading Value scaled using the current scaling for this channel See also drdaq get value and time which reports the exact time at which the reading was taken Arguments channel the channel number is between 1 and 9 See channel scaling for more information
20. 5 10 15 20 25 30 35 40 45 50 ms Stopped Trigger Single Sound Rising zoo Adding spectrum and meter views So far we have looked at the oscilloscope functions PicoScope allows DrDAQ to be used as a spectrum analyser and meter as well The three buttons on the top left hand side control the oscilloscope spectrum and meter views e Oscilloscope view view signals against time Spectrum analyser view view amplitude against frequency Meter view measure DC volts AC volts dB and frequency Copyright 2005 Pico Technology Limited All rights reserved DRDAQ044 2 11 DrDAQ User Guide 2 7 2 7 1 2 7 2 2 7 3 External sensors Overview As well as the built in sensors DrDAQ has sockets for optional external sensors When a sensor is plugged in to the external sensor sockets the software detects it and automatically scales readings For example if a temperature sensor is plugged in readings are displayed in C or if a humidity sensor is plugged in readings are displayed in RH External sensors are optional extras so can be purchased at any time For an up to date list of the available external sensors consult the DrDAQ web site at http www drdaq com Click here for the DD100 Temperature Sensor Click here for the DD011 pH Electrode Click here for the EL029 Reed Switch Click here for the DD101 Humidity Sensor Click here for the DD103 Oxygen Sensor
21. AC or DC voltage For computers that do not have an earth connection for example laptops it must be assumed that DrDAQ is not protected by an earth in the same way a battery multimeter is not protected by an earth The maximum input voltage range of any input is 0 to 5V Any voltage in excess of 30V may cause permanent damage to the unit The unit contains no user serviceable parts repair or calibration of the unit requires specialised test equipment and must be performed by Pico Technology Limited or their authorised distributors Copyright 2005 Pico Technology Limited All rights reserved DRDAQ044 2 3 DrDAQ User Guide 1 3 Legal information The material contained in this release is licensed not sold Pico Technology Limited grants a licence to the person who installs this software subject to the conditions listed below Access The licensee agrees to allow access to this software only to persons who have been informed of these conditions and agree to abide by them Usage The software in this release is for use only with Pico products or with data collected using Pico products Copyright Pico Technology Limited claims the copyright of and retains the rights to all material software documents etc contained in this release You may copy and distribute the entire release in its original state but must not copy individual items within the release other than for backup purposes Liability Pico
22. C but we only want to use it between 5 C and 110 C therefore this will be its operating input range The first calibration point should be close to 5 C so the sensor will be placed in melting ice which is known to be 0 C The second calibration point should be close to 110 C so the sensor will be placed in boiling water which is known to be 100 C It is rare that such a convenient range is available but the principle of two point calibration stays the same DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Product information 32 It is important to distinguish between the operating range and the full input range of the sensor since it would be far more difficult to calibrate the sensor between 200 C and 200 C and would yield no accuracy benefit for the user between 5 C and 110 C Non Linear X Multi point Calibration You will need more than two points to describe a non linear response curve therefore you will need to create a look up table experimentally Since you will be measuring a series of readings at unconfirmed intervals the only way to know the calibrated value is to perform the same measurement with both the sensor you are calibrating and a sensor which you know has already been calibrated Create a table of raw and scaled values similar to below x raw new sensor y scaled calibrated sensor 0 0 5 8 10 12 15 14 20 15 Both P
23. DAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Product information 14 2 7 4 ELO29 Reed Switch EL029 Reed Switch Sul aa A reed switch sensor can be used to detect the presence of a magnetic field such as that from a bar magnet or an electromagnet Alternatively a simple single pole switch can be connected to terminals inside the EL029 Size 72 x 45 x 28 mm Operating range 0 to 99 Maximum response time 2ms The EL029 Reed Switch may be connected to either Ext 1 or Ext 2 on DrDAQ To determine the optimum position for the magnet Hold the EL029 with its connecting socket towards you and the screw that fixes the lid facing up The best position for the magnet is about half way along towards the bottom of the right hand side of the EL029 case The label on the bottom of the EL029 indicates this position When a magnet is in place next to the EL029 the Reed Switch inside the EL029 closes This is shown in PicoScope and PicoLog by a change from 99 switch open to 0 switch closed Note that this percentage is an indication of the proportion of the sampling period that the switch is in the open state You may use the EL029 to connect a simple single pole switch Such as a micro switch to DrDAQ You will need to obtain a switch and some insulated connecting wire Remember to keep magnets or magnetic fields away from the EL029 when you use it with an external switch Magnetic fields will st
24. For internal sensors the following virtual resistor values should be used 1 Sound Waveform 1200 2 Sound Level 1300 3 Voltage 1500 4 Resistance 1600 5 pH 1400 6 Temperature 1100 7 Light 1000 LongName Temperatur Used in PicoLog ShortName TempC This field is not used by DrDAQ running PicoScope or PicoLog Units C Displayed on graphs MinValue 40 MaxValue 120 Note For PicoScope these values will determine the maximum and minimum values displayed in Scope View For PicoLog these values determine what Maximum range is displayed in the Graph View set in the Graph Options dialog Places 1 Number of decimal places The options are 0 1 2 and 3 With places 1 the value 15 743 would be returned as 157 meaning 15 7 With places 2 the same number would be returned as 1574 Method 0 This specifies the scaling method At the moment O table lookup is the only method OutOfRange 0 This specifies what to do if the raw value is outside the range of the table lookup The options are 0 treat as a sensor fail 1 clip the value to the minimum or maximum table value 2 extrapolate the value using the nearest two table entries Fast Yes This is Yes if the sensor is capable of generating high speed information Copyright 2005 Pico Technology Limited All rights reserved DRDAQ044 2 31 DrDAQ User Guide NoOfPoints 32 This is the number of table
25. S Copyright 2005 Pico Technology Limited All rights reserved DRDAQ044 2 19 DrDAQ User Guide Create calibration data When the measurements are completed you need to make a written calibration table 1 From your recorded results find the place near the end of the measurement time where the readings are most stable 2 Write down these temperature and humidity readings for the standard solution in a table 3 Look up the humidity that the standard solution should give for the temperature that you have recorded Write this value in your table next to the value measured by the DD101 the manufacturer of the standard solution should have provided you with a table for humidities for different temperatures 4 Fillin entries for all the standard solutions you have measured You should end up with a table something like this Chemical Measured humidity Standard humidity Temperature Potassium chloride 81 85 20 C Magnesium nitrate 50 54 21 C Magnesium chloride 30 33 20 C Keep this table safe for further reference It will be useful if you have to reset the software with the PicoLog Recorder New Settings command At this stage compare the measured and standard values If you find that the measured values differ from the standard values by more than 10 then there is something wrong You may have had a non saturated solution some contamination in the solution inadequate sealing of your test container or poss
26. Technology and its agents shall not be liable for any loss damage or injury howsoever caused related to the use of Pico Technology equipment or software unless excluded by statute Fitness for purpose No two applications are the same Pico Technology cannot guarantee that its equipment or software is suitable for a given application It is your responsibility therefore to ensure that the product is suitable for your application Mission critical applications This software is intended for use on a computer that may be running other software products For this reason one of the conditions of the licence is that it excludes usage in mission critical applications for example life support systems Viruses This software was continuously monitored for viruses during production but you are responsible for virus checking the software once it is installed Support If you are dissatisfied with the performance of this software please contact our technical support staff who will try to fix the problem within a reasonable time scale If you are still dissatisfied please return the product and software to your supplier within 28 days of purchase for a full refund Upgrades We provide upgrades free of charge from our web site at www picotech com We reserve the right to charge for updates or replacements sent out on physical media Trademarks Pico Technology Limited PicoScope PicoLog DrDAQ and EnviroMon are trademarks of Pico Technology
27. When PicoLog is first loaded the following screen will appear Welcome to PicoLog for Windows x Overview Press here for an overview of the software and its capabilities i Press here for a guided tour of the functions available you can jJ cancel the tour at any time Normal Press here to start the program running normally l Don t display this dialog next time Select the guide tour which will take you through the main functions in PicoLog Copyright 2005 Pico Technology Limited All rights reserved DRDAQ044 2 DrDAQ User Guide 2 6 2 6 1 Getting started with PicoScope Using PicoScope PicoScope software turns your PC into an oscilloscope spectrum analyser and meter PicoLog software is an advanced data logging package The decision on whether to use PicoScope or PicoLog depends on the signals you wish to measure If you wish to collect fast signals such as sound waveforms then use PicoScope if you want to collect data over a long period such as plotting battery discharge then use PicoLog When PicoScope is first loaded a title screen will be displayed then the view below should appear If this view does not appear or an error message is displayed then double check the connections and consult the technical support section of this help file PicoScope for Windows NONAME PSD ojx ikg File Edit Settings View Window Help 8 x e3 O O o msraiv ba AfSouna z or clon o
28. _driver_version 35 drdaq_get_times_and_values 41 drdaq_get_unit_info 41 drdaq_get_value 37 drdaq_get_value_and_time 38 drdaq_get_values 40 drdaq_open_unit 35 drdaq_set_do 37 drdaq_set_interval 39 drdaq_set_led 37 drdaq_set_trigger 38 drdaq_set_unit 36 Drivers 33 E ELO29 Reed Switch 14 Excel 44 G Getting started 6 Grounding 2 HP Vee 45 Humidity interface 15 L LabVIEW 44 Laptops 2 Legal information 3 LPT ports 4 M Making your own sensors 23 Measuring pH 11 Meter view 10 O Overview 2 Overvoltage protection 2 4 Oxygen sensor 21 P Parallel ports 4 pH electrode 11 Powering a sensor 24 Printer ports 4 R Reed switch 14 Repair 2 Resolution 4 S Safety warning 2 Sampling rate 4 Scaling 6 25 Scaling files 28 Copyright 2005 Pico Technology Limited All rights reserved DRDAQ044 2 47 DrDAQ User Guide Sensors 11 adding 11 Software updates 33 Specifications 4 Spectrum analyser 10 T Temperature sensor 11 Timebase 9 changing 9 Trigger 10 V Visual Basic 44 V Windows 95 98 34 Windows NT 2000 35 DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Pico Technology Ltd The Mill House Cambridge Street St Neots PE19 1QB United Kingdom Tel 44 0 1480 396 395 Fax 44 0 1480 396 296 Web www picotech com DRDAQ044 2 26 8 05
29. ample and the channels to be used for calls to drdaq get values or drdaq_ get times and values Arguments ws for block target total time in which to collect ideal_no_of samples in us ideal_no_of_samples specifies the number of samples that you intend to collect This number is only used for timing calculations you can actually collect a different number of samples when you call drdaq_get_values channels a pointer to an array listing the channels to be used The channel numbers are between 1 and 9 see channel scaling for more information no_of_channels specifies the number of channels used DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Software information 40 Returns the time taken in ms to collect the block might be greater than time requested An example of a call to this routine using channels 2 3 and 5 is int channel channels 0 channels 1 2 s channels 2 drdaq_set_interval 10000 100 channels 3 The routine returns the actual time to collect this number of samples This actual time may be greater than the target time if you specified a sampling interval that is faster than your computer can manage If the specified sampling rate was too fast you have the following choices if the total time is important collect fewer than the ideal number of samples so that the
30. ary precautions to avoid contact when preparing and using the standard solutions Note For the highest accuracy you should compare the readings from you DD101 with the readings from a calibrated laboratory standard reference humidity gauge Calibration of the sensor involves Preparation of the calibration equipment Measurement of the standard saturated solutions Creation of calibration data for the DrDAQ software A check that the calibrated sensor is accurate Note You must measure at least two different standard solutions to provide two or more fixed points for calibration Equipment you will need DrDAQ with DD101 sensor Pico DD100 Temperature Sensor At least two Standard Solutions A label for the DD101 A test container An insulated box Astand for the DD101 Optional high accuracy calibrated reference laboratory standard humidity gauge Stand It is very important that the standard solution does not enter the case of the DD101 The solution may damage the electrical components of the sensor Therefore the DD101 needs to be suspended in the test container clear of the standard solution A small stand is the best way to hold the sensor above the solution The stand may be any object open framework that is impervious to the standard solution Make sure that the material that your stand is made from is compatible with the test solutions you intend to use Copyright 2005 Pico Technol
31. ase the air flow around the sensor For example swing the sensor gently on its lead or create a constant draft using a fan Do not blow into the sensor as your breath is very humid and will produce incorrect results Never allow the sensor to get wet for example do not take a cold sensor into a warm humid environment where condensation may form inside the sensor s case DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Product information 16 Making accurate measurements The DD101 will give good readings of humidity and show trends well However if you need to make more accurate measurements you will have to calibrate the sensor The calibrated sensor could have an accuracy as good as or 5 though this depends on how well the calibration procedure is carried out The output of the sensor may vary over time For this reason you should calibrate the sensor regularly at least once a year Basis of the calibration method Calibration relies on the general physical properties of saturated solutions The humidity above such solutions in closed containers is known quite accurately and is used to calibrate the sensors Chemical salts used for this purpose include potassium chloride magnesium chloride and magnesium nitrate Note The humidity that exists above all such solutions varies with temperature Warning The standard solutions may be harmful to your skin eyes or when swallowed Take all necess
32. aw32 1 32 Scaled32 100 Scale101 Resistor 330 LongName Temperatur ShortName TempF Units F MinValue 32 MaxValue 160 Scale103 Resistor 270 LongName Light ShortName Light Units LUX MinValue 0 MaxValue 20000 Explanation of each term in the DDS file is as follows Scale100 A unique number to identify this entry Pico created numbers are from 100 upwards Customers should use numbers below 100 Resistor 330 The ID resistor value in kohms Values should be entered as decimals i e 3 3 not 3k3 Note If your DDS file contains two scales that make use of the same resistor value PicoScope and PicoLog behave differently PicoScope will not let you choose which of the scales to apply If you have only one DDS file PicoScope will use the first occurrence of the scale in the file and ignore those that come after If you have more than one DDS file the scale that PicoScope uses will be arbitrary PicoLog will allow you to select which of the scales you wish to apply For external sensors this resistor should be fitted in the sensor Customers should use one of the following resistors 1k0 2k2 3k3 5k6 7k5 and 10k The resistor used should be 1 tolerance or better DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Product information 30 The following resistor values are reserved and must not be used 330k 220k 180k 150k 120k 110k 100k 91k 82k 75k 68K
33. cilities Specify the printer port that is connected to DrDAQ Get information about the scalings available for a channel Select a scaling for a channel Take a single reading from a specified channel Specify a trigger event from a specified channel only available in block mode Collect a block of samples at fixed time intervals from one or more channels You can specify a sampling interval from 50 microseconds to 1 second If you specify an interval that is shorter than your computer can manage the driver will tell you how long it will actually take to collect the specified number of samples Under Windows the sampling may be affected by Windows activities At the least there will be gaps in the data every 55 milliseconds due to the Windows timer function There will be additional gaps if you move the mouse or have other programs running We therefore recommend using the drdaq_get times and values routine so that you can determine the exact time that each reading was taken The normal calling sequence to collect a block of data is as follows Check that the driver version is correct Open the driver Select channel scalings if required Set trigger mode if required Set sampling mode channels and time per sample While you want to take measurements Get a block of data End while Close the driver ODMDAIHDUOBWNHE Driver formats Windows 95 98 When running under Windows 95 an application is not in complete co
34. e consistent for a particular computer It should be sufficient to power a 10k thermistor if you use a 10k bias resistor for the thermistor This output can also directly power the LM35 type of IC based temperature sensor External Inputs Each external input socket has four connections Pin Function Input channel with 100k pull up to 2V5 Ground 3 Sensor type detect with 100k pull up to 2V5 4 Power approx 2mA at 3 5V Note On most computers the printer port ground is connected to mains earth If you connect the ADC ground to a non zero voltage you may damage the ADC and your computer If in doubt check whether there is a voltage difference between ground on you equipment and ground on the ADC before connecting the ADC to your equipment DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Product information 6 2 4 Channel scaling The following table gives details of the scaling for each channel Channel Input Min Value Max Value Decimal Units number Places 1 Sound waveform 100 100 1 2 Sound level 50 100 2 dBA 3 Voltage 0 5000 0 mV 4 Resistance 0 1000 1 kQ 5 pH 0 14 2 6 Temperature 0 100 1 C 7 Light 0 100 1 8 External 1 Depends on sensor 9 External 2 2 5 Getting started with PLW PicoLog is a powerful but flexible program for collecting analysing and displaying data
35. entions and undecorated names The 32 bit DLLs for Windows 95 and Windows NT use the same calling conventions so a 32 bit application will run without modifications on either system Note however that the two operating systems require different versions of the DLL file Routines drdaq_get_driver_version PREF1 short PREF2 drdagq_get_driver_version void This routine returns the version number of the DrDAQ driver You can use it to check that your application is used only with the driver version that it was designed for use with Generally speaking new driver versions will be fully backward compatible with earlier versions though the converse is not always true so it should be safe to check that the driver version is greater than or equal to the version that it was designed for use with Arguments none Returns driver version Upper byte is the major version lower byte is the minor version For example 0x0301 drdaq_open_unit PREF1 short PREF2 drdaq_open_unit short port This routine opens the DrDAQ unit connected to the specified port It then calibrates the timing functions for the computer If you wish to use more than one DrDAQ unit at the same time you should call drdaq_open_unit for each of the units then use drdaq_set_unit to select which unit to use next Arguments port the number of the parallel port that the DrDAQ is connected to 1 for LPT1 2
36. ered the calibration data correctly and repeat the process Once you have successfully calibrated your DD101 write the date on the label and stick the label on the sensor do not block the holes in the sensor with the label Testing Sensors You can check whether a sensor is working properly or not by running through the calibration procedure If you find that the sensor values differ from the standard values by more than 10 you may have a damaged sensor In this case contact Pico for assistance Copyright 2005 Pico Technology Limited All rights reserved DRDAQ044 2 21 DrDAQ User Guide 2 7 6 DD103 Oxygen Sensor DD103 Oxygen Sensor The DD103 Oxygen Sensor is used to measure the percentage of oxygen in a gas The sensor plugs into the external sensor sockets of DrDAQ Ext1 and Ext2 using the supplied cable Specification Sensor Type Galvanic Cell lead oxygen with weak acid electrolyte Input Range 0 100 oxygen Accuracy Calibrated 43 0 over operating conditions range Response Times lt 15 seconds for 90 response lt 25 seconds for 97 response Max Humidity 0 95 Non condensing Operating Temperature 5 C to 40 C Storage Temperature 15 C to 50 C Setting up the oxygen sensor Since the Oxygen Sensor has an output of OmV at 0 oxygen a single point calibration calibration can be carried out The procedure below guides you through setting up the oxygen sensor to
37. fied in the most recent drdaq_set_ interval call and returns the actual times for each reading Arguments time the time in microseconds at which each reading was taken The trigger event is at time 0 values a buffer for the readings The readings are scaled using the currently selected scaling for each channel If multiple channels are selected the readings for the channels are interleaved For example with channels 1 3 and 8 the readings in the buffer would be 1 3 8 1 3 8 1 3 8 no_of_values the number of readings to collect Returns the actual time for the block or zero if a key is pressed If a key is pressed while collecting the routine will return immediately The return value will be zero if a key was pressed and the total in microseconds if a block was successfully collected 3 2 2 14 drdaq_get_unit_info PREF1 void PREF2 drdagq_get_unit_info char str short strith short line short port If the unit on the specified port failed to open this routine fills str with a string that explains why the unit was not opened If the specified unit is open The routine returns version information about the DrDAQ DLL the Windows driver and the sampling rate Arguments str text buffer for returned string str_lth length of str ie maximum string that can be returned line line number 0 4 port lot port number 1 3
38. ibly a damaged sensor Check your calibration routine If you still get large errors contact Pico for assistance If you are using a calibrated reference this should give values very close to those quoted for your standard solutions If these values disagree by more than a few percent suspect your calibration procedure When the two are in agreement use the values given by the calibrated reference as the correct figures for your data table Once you have your calibration data you must enter it into the Pico software to calibrate the sensor Open the PicoLog Parameter Scaling Dialog Start PicoLog Recorder Click on Settings Click on Input Channels the DrDAQ Measurements dialog appears Select the input channel for the humidity sensor for example External 1 Humidity Click on the Edit button the Edit DrDAQ Measurements dialog appears Click on the Options button the Parameter Options dialog appears Click on the Scaling button the Parameter Scaling dialog appears Enter your calibration data Pull down the Scaling Method list and select Table lookup To start your calibration table click in the white rectangle the text cursor appears Type in the value that you measured with the DD101 under Raw Type a space then enter the standard value under scaled Press return the enter key Enter all the pairs of measured and standard values that you have to build your table You should end up with two columns of values No
39. icoLog and PicoScope have the facility to manually enter look up tables see the respective help files You can also make a more permanent reusable scaling table with DrDAQ Scaling Files DDS Copyright 2005 Pico Technology Limited All rights reserved DRDAQO044 2 33 DrDAQ User Guide 3 Software information 3 1 Software updates Our software is regularly updated with new features To check what version of the software you are running start PicoScope or PicoLog and select the Help About menu The latest version of software can be downloaded free of charge from the DrDAQ web site at http www drdag com Alternatively the latest software can be purchased on disk or CD from Pico Technology To be kept up to date with news of new software releases join our e mail mailing list This can be done from the main Pico Technology web site at http Awww picotech com 3 2 Writing your own software DrDAQ is supplied with driver routines that you can build into your own programs The driver routines are supplied as Dynamic Link Libraries for Windows 95 98 NT and 2000 These can be used with C Delphi and Visual Basic programs and programs like Microsoft Excel where the macro language is a form of Visual Basic Once you have installed the software the DRIVERS sub directory contains the drivers and a selection of examples of how to write your own programs It also contains a copy of this help file in text format The follow
40. ill make the internal Reed Switch operate overriding the open setting of the external switch To connect the switch follow these steps 1 Make sure that the leads from the external switch have about 5 mm of bare wire to form the connections 2 Remove the lid 3 Put the EL029 on a firm flat surface such as a table top with the fixing screw facing up and the connection socket towards you 4 Unscrew the fixing screw 5 Lift off the lid of the EL029 and put it and the screw to one side The lid should lift off easily 6 Connect the wire 7 Find the small terminal block with two screws in its top towards the back of the EL029 circuit board 8 Loosen the screws in the terminal block Do not take them out altogether 9 Thread the two wires from the external switch through one of the holes in the bottom of the EL029 10 Note If you do not wish to use either of the two holes in the bottom of the EL029 Copyright 2005 Pico Technology Limited All rights reserved DRDAQ044 2 15 DrDAQ User Guide 2 7 5 case make a hole in the side of the case just big enough for the leads to pass through Take care not to damage the electrical components 11 Leaving enough free wire to make the connection secure the leads by looping them around the central boss of the EL029 case Alternatively put a tie wrap around the leads inside the case and near the hole Make sure that the leads are securely held in the EL029
41. ing table describes each of the routines supplied with the drivers Routine Function drdaq get driver version Check that this is the correct driver drdaq_open unit Open the driver to use a specified printer port drdaq_set_unit Select which DrDAQ unit to use drdaq close unit Close the specified printer port drdaq_apply fix Modify behaviour of DLL drdaq set do Set the digital output drdaq_set led Set the LED drdaq_get value Get a single reading from one channel drdaq set trigger Set a trigger event from a specified channel drdaq_set_ interval Set the channels and time interval for the next call to drdaq_get_values or drdaq_get_times_and_values drdaq_get values Get a block of readings at fixed intervals drdaq_ get time and value Get a reading and the time the reading was taken drdaq get times and values Geta block of readings and their times at fixed intervals drdaq_get unit info Get information about an DrDAQ unit drdaq_get channel text Get text information about a DrDAQ channel eg name units drdaq_get channel info Get numeric information about a DrDAQ channel eg min max value drdaq_get_scalings Get the scaling options for a channel drdaq_set_scaling Specify the scaling for a channel DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Software information 34 3 2 1 3 2 1 1 The driver offers the following fa
42. l of the liquid Do not allow any standard solution to spill on to the top of your stand 3 Putthe DD101 and DD100 sensors onto the stand If you are using a calibrated reference put this in too Connect the DD101 and DD100 sensors to DrDAQ Take your measurements Start the PicoLog Recorder software for DrDAQ Make sure DrDAQ is receiving readings from the sensors on Ext 1 and Ext 2 7 Seal the test container and close the insulated box if you are using a fan start the fan 8 Record the temperature and humidity inside the test container for at least one hour You must wait for the temperature to stabilise and the DD101 to provide correct readings This may take up to eight hours if you have used a large container 9 Check that the DrDAQ plots for temperature and humidity have been constant over the last few minutes of your measurements If you are using a calibrated reference take a reading of this now Take care to minimise the changes in the setup so that the reading does not change significantly 10 Save your results 11 Dispose of the solution as recommended by the supplier of the chemical Remember to take adequate precautions to protect your skin and eyes when disposing of the chemicals 12 Do the measurements again for the other standard solutions You should end up with a set of recorded measurements for each standard solution Remember that you must provide at least two fixed points for calibration of the sensor o
43. midity they provide Whichever chemicals you choose make sure that the humidity they give is within the operating range of the DD101 sensor that is greater than 20 and less than 90 relative humidity You should use at least two standard solutions to give two fixed points for your calibration Standard reference books such as Kaye amp Laby Tables of Physical and Chemical Constants Longman give tables with the humidity of standard solutions For example Chemical Humidity at 20 C Potassium Chloride 85 Magnesium Nitrate 54 Magnesium Chloride 33 Note The humidity produced by the standard solution depends on the temperature If the temperature changes from 20 to 21 Celsius this could give a change in relative humidity of as much as 3 for a nominal 50 value This change would be worse for higher values of relative humidity Insulated box Because the humidity produced by the standard solution depends on temperature you should use your test container inside an insulated box A domestic cool box without the cold blocks is suitable DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Product information 18 Preparation Warning The standard solutions may be harmful to your skin eyes or when swallowed Take all necessary precautions to avoid contact when preparing and using the standard solutions Prepare your standard solutions before you start the calibration procedure Follow the instr
44. n sstdstccsciccitecdicciccdciccsccdatsesansaiiasaciaicasaianseesancasansannanancenes 33 1 Software updates ssss srserrnnrsreennnnnnnnnneennnnnnnnnnnnennnnnnnnnnneennnennnnnnne 33 2 Writing your own software eeessss rrrrrrerrrennnnnnneernrnnnnnnnnrenennnnnnne 33 a a E P E TE T T E E 46 DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Introduction 2 1 Introduction 1 1 Overview External sensors DrDAQ is a low cost data logger from Pico Technology It is supplied ready to use with all cables software and examples Features include Built in sensors for light sound level and waveforms and temperature Measure pH just plug in our standard pH electrode Sockets for external sensors Use DrDAQ to capture fast signals for example sound waveforms Digital output for control experiments Simply plug in to your PC and measure supplied with both PicoScope oscilloscope and PicoLog data logging software 1 2 Safety warning DrDAQ ground is connected directly to the ground of your computer As with most oscilloscopes and data loggers this is done in order to minimise interference You should take care not to connect the ground screw terminal outer shell of BNC or exposed metalwork of DrDAQ to anything which may be at some voltage other than ground doing so may cause damage to the unit If in doubt use a meter to check that there is no significant
45. ntrol Windows can interrupt at any time Interruptions occur every 55 milliseconds and are also caused by mouse and keyboard input As a consequence the driver cannot always take readings at fixed time intervals To deal with this the driver returns the time at which each reading was taken The 32 bit Windows 95 driver PICO VXD is installed in windows It is loaded using a reference in system ini 386enh device pico VXD The 32 bit Windows 95 98 driver is accessed using the file DRDAQ32 DLL it is installed in drivers The DLL uses STDCALL linkage conventions and undecorated names The 32 bit DLLs for Windows 95 and Windows NT use the same calling conventions so a 32 bit application will run without modifications on either system Note however that the two operating systems require different versions of the DLL file Copyright 2005 Pico Technology Limited All rights reserved DRDAQ044 2 35 DrDAQ User Guide 3 2 1 2 3 2 2 3 2 2 1 3 2 2 2 Windows NT 2000 The Windows NT 2000 driver PICO SYS is installed in windows The operating system must be told that the driver is available this is normally done automatically by the setup program but can also be done manually using the the regdrive exe program which is copied into the PICO directory Type in regdrive pico The Windows NT 32 bit driver is accessed using the file DRDAQ32 DLL it is installed in drivers The DLL uses STDCALL linkage conv
46. ogy Limited All rights reserved DRDAQ044 2 17 DrDAQ User Guide Test container Your test container should be only just big enough to hold the DD101 and DD100 sensors the stand and a small quantity of standard solution the solution should fill approximately 5 of the volume of your container It will also have to be water tight with a seal that allows you to pass the leads for the sensors into the container Note The smaller your container the more quickly the humidity will stabilise You can reduce the time taken for the system to stabilise by forcing the air in the container to circulate This will require a fan that does not introduce heat into the container it must be driven by a shaft or magnetic coupling so that the motor is outside the container If you are going to compare the values measured with the DD101 and a calibrated reference your container will have to be large enough for the reference sensor too Make sure that the material that your container is made of is compatible with the chemicals you are going to use If the chemicals react in any way with the container the humidity reference will not be correct Standard Solutions Warning The standard solutions may be harmful to your skin eyes or when swallowed Take all necessary precautions to avoid contact when preparing and using the standard solutions There are several chemicals that have been measured under laboratory conditions to find out what hu
47. or the readings to stabilise gently stirring helps 3 Make a note of the reading and repeat the procedure for each of the buffer solutions do not forget to wash the probe clean before swapping from one buffer to another 4 You should now have a table of readings similar to the one below pH Buffer value at 25 C Measured value from DrDAQ 4 01 4 06 7 00 7 07 10 01 9 92 pH calibration with PicoLog As already mentioned you will need to note down the measured pH value and compare it with the actual value to create a lookup table Then follow the steps below Got to Settings and click on Input Channels on the pull down menu The converter input type will then be displayed check settings and click OK You should now see the DrDAQ measurements box Select pH and click Edit Click Options from the Edit measurement box Now click on Scaling and select Look up table from the menu box Enter the real measured pH value below Raw and the actual value in Scaled similar to the table in the previous section 7 Click OK for all open boxes and verify the calibrated pH readings N Oo of Storing pH electrodes If KCI solution is not available then any pH4 buffer solution will be suitable for storing electrodes KCI is recommended because this is inside the bulb of the electrode Tap water would be acceptable but is not ideal Do not under any circumstances use de ionised or distilled water DR
48. r Blof plow l low zl a Q A eae peace j I ee are j I I 1 j retin aad 4 4 4 4 2s j 1 1 1 1 1 1 1 1 1 1 1 1 1 e aa Trigger poo J Try clicking your fingers over the microphone the trace on the screen should react DrDAQ is now successfully installed and working DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Product information 3 2 6 2 Adding an oscilloscope channel It is possible to display up to 4 different channels on any one particular scope window Add another channel by going to the drop down menu B and assigning it to Temp Put your finger on the temperature sensor and notice the rise in temperature PicoScope for Windows NONAME PSD of x Ay File Edit Settings View Window Help 8 x a 10 msjdiv x1 AfSouna z fo c plot for D Off aT ear ae i n Ser ee Running Trigger None gt y zoo Copyright 2005 Pico Technology Limited All rights reserved DRDAQ044 2 9 DrDAQ User Guide 2 6 3 Changing the oscilloscope timebase The timebase can be adjusted by selecting the drop down menu shown below Change the timebase to 5 ms div PicoScope for Windows NONAME PSD dy File Edit Settings View Window Help 8 x Ae LJ QJ 10 msiaiv A fa Alsouna for 1 msjdiv Temp lor 2 ms di
49. rights reserved DRDAQ044 2 39 DrDAQ User Guide Arguments enabled this is TRUE if the DrDAQ is to wait for a trigger event and FALSE if the DrDAQ is to start collecting data immediately auto_trigger this is TRUE if the DRDAQ is to trigger after a specified time even if no trigger event occurs This prevents the computer from locking up if no trigger event occurs auto_ms specifies the time in ms after which auto_trigger will occur channel specifies which channel is to be used as the trigger input The channel number is between 1 and 9 see channel scaling for more information dir the direction can be rising or falling threshold this is the threshold at which a trigger event on the specified channel takes place It is scaled using the currently selected scaling for the trigger channel For more information see Scaling delay this specifies the delay as a percentage of the block size between the trigger event and the start of the block Thus 0 means the first data value in the block and 50 means that the trigger event is in the middle of the block Returns none 3 2 2 11 drdaq_set_interval PREF1 unsigned long PR us for block ideal_no_of_samples EF2 drdaq_set_interval unsigned long unsigned long short channels short no_of_channels This routine specifies the time interval per s
50. sible to plug the DrDAQ directly to your parallel port however it is recommended that the parallel port cable supplied is used for ease of access to the unit If another device such as a printer or scanner is already connected to the parallel port and your computer only has one parallel port then the other device will have to be unplugged before DrDAQ can be connected The DrDAQ must be connected directly to the parallel port via the cable supplied the use of other cables printer sharers port splitters software dongles may result in DrDAQ not working If you wish to add additional parallel ports to your PC Pico sells a dual parallel port card that can be installed inside your PC USB to parallel port converters will not work with DrDAQ but can be used with your printer to free up the main parallel port for DrDAQ Copyright 2005 Pico Technology Limited All rights reserved DRDAQ044 2 DrDAQ User Guide 2 3 Connections Channel Input Connection pH BNC connector Voltage input Screw terminal Resistance inputScrew terminal Digital output Screw terminal External inputs FCC68 4 pin connector Digital output The output pin can be used either as a digital output or as a voltage source Note DrDAQ does not provide any additional protection for this output When using the pin as a voltage output the output impedance will vary between computers from about 1 to 3 kilohms but will b
51. sing LabVIEW for Windows 95 version 4 0 While it is possible to access all of the driver routines described earlier it is easier to use the special LabVIEW access routines if only single readings are required The drdaq llb library in the DRIVERS sub directory shows how to access these routines To use these routines copy drdaq 11b and drdaq32 d11 to your LabVIEW user 1lib directory You will then find a sub vi to access a DrDAQ channel and an example sub vi that demonstrates how to use it You can use one of these sub vis for each of the channels that you wish to measure The sub vi accepts the port 1 for LPT1 and channel and returns a value Copyright 2005 Pico Technology Limited All rights reserved DRDAQ044 2 45 DrDAQ User Guide 3 2 3 7 HP Vee The example routine drslow vee is in the drivers sub directory It was tested using HP Vee version 5 under Windows 95 and Agilent Vee 6 beta under Windows 98 The example shows how to collect a block of data from DrDAQ DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Index 46 Index A Accuracy 4 C C 43 C 43 Calibration 2 31 Channels 8 adding 8 Connecting 4 Connections 5 D DDO11 pH Electrode 11 DD100 Temperature Sensor 11 DD101 Humidity Sensor 15 DD103 Oxygen Sensor 21 Delphi 43 Digital output 4 drdaq_apply_fix 36 drdaq_close_unit 36 drdaq_get_channel_info 42 drdaq_get_channel_text 42 drdaq_get
52. steresis The sensor may give a different output value when rising to a voltage than if it falls toa voltage This is something that is difficult to eliminate and should be taken into account Copyright 2005 Pico Technology Limited All rights reserved DRDAQ044 2 27 DrDAQ User Guide Once the sensor has been selected and all of the above has been considered the design of some scaling circuitry can begin There are many ICs on the market that can be purchased cheaply that deal with the above potential problems look into these before re inventing the wheel and spending expensive development time designing a circuit that can be purchased for a few pounds Some simple scaling examples Example 1 Interfacing a Resistive sensor 2 5 volts Notes Light dependent resistor LDR can be used in conjunction with a fixed resistor to measure light level A suitable LDR sensor can be obtained from Maplin Electronics part number N53AY A resistor R of around 500k is suitable Example 2 Measuring 4 20 mA Current Notes 20 mA output is the Industry standard for interfacing between a control center data logger and a remote process such as a sensor for this reason 4 20 mA sensors are very common 4 20mA For relatively small currents a simple shunt resistor can be used to convert the current into voltage which the DrDAQ can then measure A suitable resistor R for the DrDAQ is 120 ohms This would give
53. te Your table must have at least two pairs of values 14 Click OK to close the dialogs 15 Click on the OK button to close the Parameter Scaling dialog the Parameter Scaling dialog disappears 16 Click on the OK button to close the Parameter Options dialog the Parameter OND Oe oS i b i M O oo DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Product information 20 Options dialog disappears 17 Click on the OK button to close the Edit DIDAQ Measurements dialog the Edit DrDAQ Measurements dialog disappears 18 Click on the OK button to close the DrDAQ Measurements dialog the DrDAQ Measurements dialog disappears This completes the entry of the calibration data Note You can remove the calibration data by opening the Parameter Scaling dialog and setting the drop down list to none If you want to completely delete the calibration scaling you can either edit and delete the entries in the Parameter Scaling dialog or use the New Settings command from the main menu If you use the New Settings command all scaling data will be lost Check the calibration To be sure that the calibration has been successful you must repeat the measurement stage of the procedure When the check measurements have been completed there should be very close agreement between the measured and standard values that is within 5 of the value If this is not the case check that you have ent
54. tone MEK Copyright 2005 Pico Technology Limited All rights reserved DRDAQ044 2 23 DrDAQ User Guide 2 8 2 8 1 Making your own sensors Overview Making your own sensors for DrDAQ is quite straightforward provided that you follow these guidelines Designing a DrDAQ sensor overview Each external sensor socket has two channels one is an auto detect to inform the software which type of sensor it is and one analogue input that represents the sensor reading There are four pins on the External inputs This view is looking into the Ext socket on DrDAQ in the direction of entry of the plug Pin 1 Signal Input Pin 2 Ground Pin 3 Auto Detect Pin 4 VCC Suitable connectors to these external inputs are FCC 68 4 4 plugs Alternatively the DrDAQ sensor adapter break out box from Lascells can be used The pins are clearly labelled on the box The range of Auto Detect and Signal Input voltage must be between 0 and 2 5 volts This is a hardware limitation and any signals outside of this range will not be read by the unit Any voltages greater than 30 volts fed directly into the device are likely to damage the unit and can cause errors with all other DrDAQ readings The Signal Input channel has 100 kQ pull up resistors to 2V5 so that the input can be resistive as well as voltage DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Product information 24
55. uctions given by the manufacturers of the solutions you are using A slurry of un dissolved chemical in your solution should improve the stability Make sure that all the containers you use for preparation are thoroughly clean before use as contamination of the solution will alter the humidity Do not use tap water to make up the solution as this is insufficiently pure use distilled and de ionized water Allow time for the solution to reach room temperature before use Always use fresh solutions to ensure that the chemicals have not become contaminated or degraded Allow the standard solutions and other equipment to reach the same temperature ideally 20 C before you start Measure humidity 1 Setup the equipment 2 Clean the equipment Make especially sure that the test container is clean rinse it out with distilled water 3 Put the test container into your insulated box Warning The standard solutions may be harmful to your skin eyes or when swallowed Take all necessary precautions to avoid contact when preparing and using the standard solutions Caution It is very important that the standard solution does not enter the case of the DD101 The solution may damage the electrical components of the sensor 1 Put some of the standard solution into the test container The solution should occupy about 5 of the volume of your container 2 Put the stand into the test container The stand should give you a clear platform above the leve
56. unt when designing scaling circuitry Sensitivity The DrDAQ has 10 bit resolution over the 0 to 2 5 V input range this means the sensitivity is 2500 mV 2410 2 44 mV DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Product information 26 This means that the DrDAQ can detect changes in voltage as low as 2 44 mV To make the most of the resolution the signal output from the sensor should use as much of the input range of the DrDAQ as possible Linearity As illustrated below not all sensors have a linear response Linear Response An Example of Non Linear Response Y Y x x A linear response is one whose output versus input graph is a straight line A typical example of this type of response is a photodiode Note a non linear response curve cannot be calculated using a simple y ax b formula A typical example of this type of response is an LDR Offsets x The above linear non linear responses could have a voltage current resistive etc offset that may need taking into account It is quite usual to see offsets in output signals from sensors Sensor output The DrDAQ requires an input signal in DC volts or resistance the sensor in question could give an output in other units such as resistance current or AC volts Drift It is possible that the sensor output drifts over time this may involve re calibration of the sensor at set time periods or some self calibration Hy
57. using Ohm s Law 0 4 volts at 4 mA 2 4 volts at 20 mA DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Product information 28 2 8 4 Example 3 Measuring 10 volts Notes This is a simple circuit that uses a potential divider to reduce the voltage going into the DrDAQ by four R1 3k amp R2 1k The resistors are calculated using Ohm s Law V IR Auto Detect Auto detect resistor is placed between Ground Pin 2 and Signal Detect Pin 3 The Value for the resistor should be selected from one of the following common values 1k0 2k2 3k3 5k6 7k5 10k It is necessary to have an auto detect resistor so that the software can automatically scale the input signal into the property that it represents DrDAOQ scaling files DDS The DrDAQ driver has built in scaling for each of the built in and Pico supplied sensors You can incorporate scaling for your own sensors by adding a file called drdag dds which contains details of your sensor The values returned by the driver are integers that represent fixed point decimal number For example the driver treats pH as a value with two decimal places so a pH of 7 65 is returned as 765 You can call the routine drdaq_get channel info to find out how many decimal places a channel is using and also to get a divider that converts the integer value to the corresponding real number For pH the returned divider is 100 so 765 divided by 100
58. v B Temp bi Off 5 ms div C D J J J4 4 wee dee dee dee de ed Running Trigger None gt DRDAQ044 2 Copyright 2005 Pico Technology Limited All rights reserved Product information 10 2 6 4 2 6 5 Using the trigger The PicoScope trigger can be used to capture infrequent or one off events As an example click your fingers over the microphone a waveform is displayed but vanishes as soon as the display updates The correct way to capture such a signal is to use a trigger Stop PicoScope click on the Go icon at the bottom left hand corner of the window or press the space bar and select a single trigger using the trigger options at the bottom of the screen Press the space bar to start PicoScope and click your fingers over the microphone The single trigger option means that PicoScope stops running when it has captured a signal PicoScope for Windows NONAME PSD OF x ay File Edit Settings View Window Help 8 x 5 msjdiv x1 AlSound B Temp ne r pepe pa en pamane pe a pone i 4 DON 2 a a anaes Se igus a aes a EE Bik lt 54 f gt pos lees leak Seales aoa ae cc A B0 ee a eS COE a Ee eee a Pee ae a tee eee ene 50 Sone N ee eT a OA FASE 1 LA NS 40 ry ay aca oe o ee ns o 30 60r 1 F T q r T q r 1 0 eE T aie E ene E Seen ee e N ELA a E EON ENA E a ee o 0

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