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APPENDIX

D

APPENDIX D

AP4 HEAD DESIGN DETAIL

AP4 HEAD MOULDING IMPROVEMENTS

From January 2004, new AP4 Porometer heads incorporate detail design changes to improve the
ergonomic handling, and to reduce the wear and tear experienced after prolonged use. These
improvements are derived from many years of experience with AP4 porometers which have been
employed in a wide variety of field situations.
The main features are highlighted below. The new mouldings are immediately recognisable from
the finger grip mouldings and the Delta-T name. New tooling has been produced to increase the
consistency of manufacture of the cup and leaf pad gaskets and seals.
The functionality of the AP4 head is not changed, and it will show increased life and durability in
field use.

Finger grip
moulding

Improved hinge pin
and alignment

Reinforcement webs to
increase rigidity

Improved cable
strain relief

Cup and leaf seals
improved

AP4 head Design Detail

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Summary of Contents for AP4

Page 1: ...User Manual for the Porometer type AP4 DELTA T DEVICES AP4 UM 3 ...

Page 2: ...Using t h i s manual T h i s manual provides i n f o r m a t i o n necessary t o c o r r e c t l y i n s t a l l and operate t h e Delta T Porometer type AP4 Page 2 ...

Page 3: ...anuary 2004 Nick Webb Tom Bragg Nick Webb Richard Spencer John Wood Chris Nicholl Edmund Potter Artwork Nick Webb Anne Simpson Delta T Devices Ltd 128 Low Road Butwell Cambridge CB5 OEJ England Phone 44 l638 742922 Fax 44 1638 743155 E mail tech support delta t co uk Page 3 ...

Page 4: ...nked f o r t e s t i n g e a r l y prototypes John Monteith and Gaylon Campbell are thanked f o r t h e i r work on t h e theory John Monteith and Edward Arnold Publishers are thanked f o r permission t o r e p r i n t an e x t r a c t from P r i n c i p 7es o f Environmenta 7 Phys ics Jonathan P r i c e i s thanked f o r h i s advice i n How t o w r i t e a computer manual published by Benjamin C...

Page 5: ...RODUCTlON 5 2 WARNINGS 7 3 UNPACP I JC AND INSTALLATION 8 4 SETTIMG UP AND SHUTTING DCWV 10 5 ClOW TO DRIVE TkE FOROMFTEE i3 5 l LAYOUT 14 5 2 CVITROL KEYS 18 5 4 MENU VIGATICIX 2 3 6 llOW TO TAKE READINGS 27 Page 5 ...

Page 6: ...esign has been s i g n i f i c a n t l y improved by the use o f a microprocessor t o release the user from the burden o f frequently r e p l o t t i n g c a l i b r a t i o n graphs The process i s now much simpler and quicker It also needs doing less frequently because the AP4 can correct f o r changes i n temperature Readings are automatically converted i n t o u n i t s o f resistance o r cond...

Page 7: ... A LEAF OR THE CALIBRATION PLATE I N THE HEAD WHEN THE AP4 I S NOT CYCLING WHOLE INSTRUMENT AVOID STORAGE OR USE ABOVE 80 RH PROTECT THE AP4 FROM WATER AVOID DEEP DISCHARGE OF BATTERY RECHARGE A FULLY DISCHARGED BATTERY IMMEDIATEL Y DO NOT CONNECT BATTERY CHARGER TO THE WRONG MAINS VOLTAGE YOURSELF DO NOT EAT THE DESICCANT or a n y o t h e r p a r t o f the p o r o m e t e r YOUR ENVIRONMENT The b...

Page 8: ...d bag and t h e case One Universal RS232 Ribbon Cable and Adapter One AP4 Battery Charger One 3 and one 54 i n d i s k s w i t h data retrieva 1 software One Consumables k i t paper pads tape 500 g s i l i c a gel s i l i c a gel tube cup s e a l cup gasket cup i n s e r t two screws OPTIONAL ACCES SORI S One AP4 Spares K i t type PSKI see l i s t i n Chapter 13 Extra AP4 Consumables K i t type PC...

Page 9: ...Unpacking and Insta 7 7at ion PACKING LIST QUKU GVlOE OPTIONAL ACCESSORIES YOU WILL ALSO NEED Page 9 ...

Page 10: ...up memory e i t h e r erase the readings o r output them t o a p r i n t e r o r computer See Chapter 6 4 SHUTTING D O W N Short term shutting down f o r less than 2 weeks Press OFF button twice Place head and head cable i n pocket provided Zip up case Protect from dust humidity greater than 50 RH smoke and organic solvent fumes and other pollutants Long term Charge battery Recharge battery every ...

Page 11: ...S e t t ing up shut ting down Setting up Page 1 1 ...

Page 12: ...How t o drive the porometer Page 12 ...

Page 13: ...the layout then inspect each control i n d e t a i l The Chapter ends w i t h maps showing a l l the journeys you can take through the software Unlike a car journey nothing d r a s t i c w i l l happen i f you press the wrong button So f e e l f r e e t o jump t o the next Chapter How t o take readings and learn by t r i a l and e r r o r i f you wish CONTENTS W LAYOUT The Porometer head u n i t T...

Page 14: ... the cup a second microchip thermistor i s buried i n the translucent f l e x i b l e s i l i c o n rubber pad These measure the cup and l e a f temperatures respectively One control button i s mounted on the head next t o the l i g h t sensor The cable attached t o the head contains a tube f o r a i r as well as signal wires The tubing plugs i n t o the container o f s i l i c a gel desiccant cry...

Page 15: ...Layout THE HEAD UNIT Page 15 ...

Page 16: ...p a r t i c u l a r options t o be f a i r l y i n t u i t i v e Options a re selected and a c t i v a t e d using t h e and GO keys described below You can a d j u s t t h e c o n t r a s t w i t h t h e LCD knob THE KEYBOARD The standard QWERTY keyboard on t h e case o f t h e porometer does not c o n t r o l t h e porometer a t a l l It i s j u s t used f o r adding o p t i o n a l notes t o re...

Page 17: ...Layout L l d c o n t r o l s and Keyboard SELECT SETTINGS S N I N C F E R S OE CREASE SCROLL NEXT OPT Od CONTROL ANEL RCCEPT 60 I I I LCD U 1 A d d NVERSE W E 0 I W LL BE SELECTED F You PRESS W Page 17 ...

Page 18: ...e and recharging Chapter 10 1 HELP KEY The HELP key provides context sensitive information on what t o do next Up t o 7 screens o f help may be provided Press HELP again t o read the next screen Press any other key t o return t o the program EXIT KEY The EXIT key i s used t o leave a menu without selecting any option The program returns t o t h e next higher menu l e v e l Use it t o go backwards ...

Page 19: ... GO Wait Press GO Press GO wake up s e l e c t READ loop w a i t i n g START reading cont inues ACCEPTS readi ng STORES r e s u l t OFF M A I N MENU INSERT LEAF READING CYCLE STORE READING INSERT LEAF THIS PERMITS ONE HANDED OPERATION OF THE POROMETER A t any stage other options can be selected v i a t h e key o r t h e previous menu can be selected v i a the EXIT key I f a t any s t a g e t h e p...

Page 20: ...a l i b r a t i o n f o r a new l i g h t sensor and t o zero t h e e l e c t r o n i c c i r c u i t which measures t h e leaf cup temperature d i f f e r e n c e See a l s o L i g h t sensor c a l i b r a t i o n chapter 10 8 Thermistor c a l i b r a t i o n chapter 10 10 Accessing t h e SET SCREEN w i l l display three head c a l i b r a t i o n c o e f f i c i e n t s used t o characterise wat...

Page 21: ... 24 hour See also Menu navigation advanced Chapter 5 3 Table o f s e t t i n g s options Chapter 5 3 1 PLUS KEY MINUS KEY The p l u s and minus key are used t o change d e f a u l t s e t t i n g s Examp7e To change the date I press ON I Wakes MAIN MENU USER ACTI O N I I Day o f month shown i n inverse video POROMETER l I 1 Press l Day o f month increments ACTION asleep Press SET DISPLAY o f f CLO...

Page 22: ...Menu navigation Page 22 ...

Page 23: ... l possible courses o f action i s shown i n the beginners map on page 24 Use t h i s t o f i n d your way around Behind most o f the action screens i s a settings screen I t s where you go t o check o r change most default s e t t i n g s and options A composite map including these i s shown i n the advanced map on page 25 I t i s also on the laminated p l a s t i c Quick Reference Guide A t a b ...

Page 24: ......

Page 25: ...S E N G S Beepmg m READING CYCLE Un ts Pressure STORE SETTINGS STORE READING Plant a u CLOCK SETTINGS CALIBRATE SETTINGS OUTPUT SETTINGS Cup type INSERT PLATE Order Position m Units m RH Set m Pressure Handshake laimila W CALIBRATION CYCLE I Light a c t o r l I ...

Page 26: ...YCLE SET READ READINGS CYCLE SET and a l s o CALIBRATE INSERT PLATE SET U n i t s Pressure cm S mm S m2 S mo7 1 S cm 7 S m 1 mm01 m 2 S 600 t o 1200 hPa mbar CALIBRATE INSERT PLATE P o s i t i o n Set R H CUP type 0rder U n i t s Pressure s l o t t e d o r c i r c u l a r 1 t o 6 o r 6 t o 1 as above OUTPUT OUTPUT READINGS From group OUTPUT OUTPUT READINGS SET SHIFT KEY OFF together use when i n s...

Page 27: ...readings and enjoy yourselves Before running an experiment you should know what a porometer i s what it i s used f o r and why you are using it I f not do a small p i l o t project Get and process some data before doing a b i g project Before taking readings run through the following Check the warnings Chapter 2 Check t h a t you have everything you need Chapter 3 Are you f a m i l i a r w i t h t...

Page 28: ...g I s it OK I f OK accept it and measure next position Do a l l 6 positions I n s t a l l c a l i b r a t i o n data Put l e a f i n head Se1ect ISTARTI The AP4 s t a r t s taking readings the reading The AP4 stops taking readings Choose one o f these options Repeat the measurement o r go on t o the next l e a f P It o return t o the main menu You can then REVIEW the data n F i n a l l y data can ...

Page 29: ...sible Avoid exposing the cup t o organic solvents and smoke Keep ca 1ibrat ion p late c lean avoid finger grease Remove excess water from paper pad before tap ing i t t o the ca 7 ibrat ion plate Reca 1ibrate whenever the temperature changes by more than 5 C Reca 7 ibrate when changing RH set point Do not a 7 low battery t o remain discharged Prepare and p7an your experiments see Chapters 7 8 See ...

Page 30: ...as what u n i t s you want t h e r e s u l t s displayed i n and what t i t l e s t o use f o r groups o f data S e t t i n g t h e communications protocol w i t h t h e p r i n t e r o r computer i s a choice you must get r i g h t Up t o now you have j u s t used what we might c a l l a c t i o n screen displays They always have a t l e a s t one o p t i o n displayed on t h e bottom l i n e rep...

Page 31: ... read Figure Press GO t o navigate around t h e reading loop Figure Navigating t h e READ loop EL auqw c o PRESS T o w w e RRWNO XREEN PRESS Bm TO CHRh l rE SEV1NGS Page 31 PUE SmFOP PRE IM SNENUW E S Sm M E ...

Page 32: ...h e cup seal and l e a f I f t h e pump comes on press o r This disables t h e pump u n t i l you press GO Recalibrate when you change t h e R H Set p o i n t You may a l t e r t h e l e a f and plant number i f you wish This w i l l never cause you t o lose data The AP4 w i l l automatically increment t h e l e a f number i f you do nothing The AP4 stores readings i n groups which you can name v ...

Page 33: ...90 2 41 pm GROUP beet plot 5 Date 9 11 90 Set RH 50 Units s cm Press 1000 hPa 0 Time Plant Leaf Reslst Cup 1 Cup Leaf Llght Notes TYPICAL PRINT OUT 2 00 pm l 1 2 00 12 6 1 2 15 looks pretty rough 2 01 p o 1 2 98 12 2 1 1 45 wlndy agaln 2 O pm 1 3 2 80 11 8 0 7 40 ...

Page 34: ...er 8 f o r our c o l l e c t i v e wisdom on good experimental technique CYCLE SETTINGS SCREEN DISPLAY This r e f e r s t o a small loudspeaker When ON i t goes Beep beep i f two consecutive readings are w i t h i n 2 Combined w i t h t h e use o f t h e GO b u t t o n on t h e porometer head t h i s allows you t o take and s t o r e readings w i t h o u t needing t o look a t t h e screen a t a l...

Page 35: ...How t o read READINGS CYCLE SCREENS Page 35 ...

Page 36: ... h t f u l l y when you do t h i s STORE SETTINGS SCREEN The l e a f number automatically increments by 1 every time you s t o r e a reading You can also change i t manually i f you wish w i t h the and keys i n the normal way Increment t h e p l a n t number w i t h the button when you change t o another p1ant I f you want t o you can label your p l a n t s w i t h these numbers A c t u a l l y y...

Page 37: ...How t o read STORE READINGS SCREENS Page 37 ...

Page 38: ...Ca 7 ibrat ion THE CALIBRATION LOOP RERD CRL BRWE REVIEW OUTPUT Page 38 ...

Page 39: ... t e the porometer using the c a l i b r a t i o n p1ate I Preparation I The c a l i b r a t i o n loop I I n s e r t p l a t e 4 Calibration cycle I I n s e r t p l a t e subsequent p l a t e positions I I n s t a l l c a l i b r a t i o n H Summary Page 39 ...

Page 40: ... m1 Tissue paper o r b l o t t i n g paper You may wish t o use a barometer such as t h e wristwatch style one which we can supply as an accessory Without i t a 100 hPa mbar pressure change o r a 1000 m change i n a l t i t u d e w i l l cause a 10 e r r o r i n measured resistance I f t h e pressure does not change s i g n i f i c a n t l y between c a l i b r a t i o n and measurement then you c...

Page 41: ...Ca 7 ibrat ion Preparat ion Page 41 ...

Page 42: ...ING THE FILTER PAD Wet the paper a l l over w i t h d i s t i l l e d water Remove t h e excess water w i t h b l o t t i n g paper o r absorbent t i s s u e paper Repeat two more times w i t h f r e s h d r y absorbent paper Page 42 ...

Page 43: ...Ca 7 ibrat ion Preparat ion Page 43 ...

Page 44: ...mooth down t h e tape t o remove any a i r pockets Return the c a l i b r a t i o n p l a t e t o i t s p l a s t i c zipper lock bag u n t i l needed This w i l l slow down t h e r a t e a t which i t d r i e s o u t and a l s o keeps i t clean I n our experience i n t h e U K i t has stayed damp f o r t h r e e days i f kept i n i t s bag Protect t h e p l a t e from greasy f i n g e r s Leave f...

Page 45: ...Ca7ibration Preparation Page 45 ...

Page 46: ... I n s e r t Plate C a l i b r a t i o n c y c l e and I n s t a l l The program a u t o m a t i c a l l y keeps t r a c k of where you are I t w i l l lead you through t h e measurement of a l l s i x p o s i t i o n s on t h e c a l i b r a t i o n p l a t e b e f o r e a s k i n g you whether t o i n s t a l l t h e new c a l i b r a t i o n Page 46 ...

Page 47: ...Ca7ibration loop Page 47 ...

Page 48: ... n d i c a t e s t h e f i x e d value t h a t t h e porometer w i l l c y c l e a bout What t o do Select Set R H and press o r t o t e m p o r a r i l y d i s a b l e t h e pump Open t h e head and wave i t about Read t h e Head R H t o determine t h e ambient RH Adjust t h e Set R H value w i t h t h e t o r key t o be c l o s e t o ambient Press SET t o c a l l up and change any o f t h e d e ...

Page 49: ...Calibration loop P ACT O N INSERT PLATE Paae 49 ...

Page 50: ...release enough moisture t o r a i s e t h e cup RH by a f i x e d amount Dry a i r i s then pumped through t h e chamber u n t i l t h e RH i s a few percent below t h e s e t p o i n t The c y c l e repeats u n t i l you press GO t o ACCEPT t h e l a s t reading CYCLE SETTINGS B e e p i n g ON o r OFF This r e f e r s t o a small loudspeaker When ON i t goes Beep beep i f two consecutive readings...

Page 51: ...Ca7ibrat ion 7oop CALIBRATION CYCLE Page 51 ...

Page 52: ... t i l you have worked through o r a t l e a s t attempted t o work through a1 l 6 p l a t e p o s i t i o n s and then accepted t h e c u r v e f i t o p t i o n which w i l l appear l a t e r A f t e r t h a t t h e r e s u l t s w i l l be r e c a l c u l a t e d u s i n g t h e c u r r e n t measured t r a n s i t times and t h e o r e t i c a l p l a t e values as data The two s e t s o f rea...

Page 53: ...Ca 7 ibrat ion loop Page 53 ...

Page 54: ... o f t h e r e s i d u a l e r r o r s T h i s f i g u r e i s u s e f u l when c a l i b r a t i n g t o check t h a t t h e c a l i b r a t i o n ran OK I f t h e e r r o r i s 5 then go ahead and INSTALL i t I f t h e e r r o r i s 10 t o 15 then look up and down t h e r e s u l t s column and redo t h e worst reading W e quote t h e porometer t o be accurate t o t 20 once i t i s a c c u r a t...

Page 55: ...INSTALL CALIBRATION Page 55 ...

Page 56: ... r leave i t a t 1000 hPa mbar I I n s e r t damp c a l i b r a t i o n p l a t e a t p o s i t i o n I Ensure i t f i t s snugly I Press GO t o s t a r t t h e reading I Wait u n t i l readings are s t a b l e then press GO t o ACCEPT it I Move p l a t e t o next p o s i t i o n and repeat u n t i l a l l 6 p o s i t i o n s are read I Select CURVE FIT The porometer then f i t s a c a l i b r a t...

Page 57: ...Review Page 57 ...

Page 58: ...Review REVIEW Select REVIEW from t h e M A I N MENU Use t h e and keys t o step through t h e data No e d i t i n g can be done and no s e t t i n g s changed w i t h i n REVIEW Page 58 ...

Page 59: ...Review REVIEW Page 59 ...

Page 60: ... Page 60 ...

Page 61: ... software t c download the data t o your computer CONTENTS I COMPUTER Fr eparifig yx r ccrnputer Instal l ing t h e data rscr ieva software 2i rsr ing the scftwar e Xhat happens or your canputcr S een Printing d i r e c t La your c inter Control ii n g the AFd Printer w j l l n c t p r i n t 7 1 E A X GTF A J4 FETRlF VK FOR WINDOWS SCFTWAHF is now suppii d Page 6 1 ...

Page 62: ... name COM 1 on your computer WARNING Do not connect it to a parallel port I t will not work Use t h e ribbon cable t h a t we supply i f possible This i s compatible w i t h most PC AT and XT computers and Epson type p r i n t e r s Use the 25 t o 9 p i n adapter i f you have t o The I B M PC AT and some other computers need i t OUTPUT READINGS Page 62 ...

Page 63: ... o a floppy d i s k o r hard d i s k sub directory Store the o r i g i n a l floppy d i s k i n a cool dry safe place RUNNING THE SOFTWARE Change t h e current d r i v e and or d i r e c t o r y t o where you want t h e received AP4 data t o be stored I f a copy o f RETRIEVE EXE i s n o t i n t h e current d i r e c t o r y it needs a PATH i n AUTOEXEC BAT t o t h e d r i v e d i r e c t o r y whe...

Page 64: ...en t i n k e r i n g w i t h these perhaps a colleague changed them t o connect up a p r i n t e r then you may have t o change them back See Setting the RS232 Parameters a t t h e back o f t h i s chapter f o r f u r t h e r d e t a i l s The second screen requires you t o enter t h e name o f t h e d i s k f i l e f o r t h e AP4 data A l i s t o f f i l e s i n t h e c u r r e n t d i r e c t o...

Page 65: ...Esc to exit 0 1 Enter nane of disk f i l e or press I Files on default directory C MRTH POLY REIRIEUE 3 3OffLY CAL CS 41 CfiL HODATA RETlaPIX RETRIEUE EXE RETAIEUE PIX SPIUS1NG W TESTAP4 O n W4 O U T P U T READINGS screen specify which group t o start output fr n I Press when ready Auaiting data from W4 amorpress 1 ESC 1 to exit program bytes of data receiued ok Data format i s m Data uritten t o ...

Page 66: ... f data being sent Press GO t o SEND W h i l s t t h e data i s being sent you can t e l l t h e porometer t o PAUSE t e m p o r a r i l y GO w i l l s t a r t i t again You can a l t e r n a t i v e l y decide t o d e l e t e t h e data The software w i l l ask you t w i c e t o prevent mistakes PRINTER WON T PRINT Check t h e RS232 parameters are s e t c o r r e c t l y see below Check t h e cab...

Page 67: ...0 9 1670 g r a s s GROUP 5 2 19 p l a n t s r e s D a t e 21 05 91 S e t RH 45 U n i t s s cm Press 1000 hPa Time P l a n t L e a f R e s i s t Cup T Cup Leaf L i g h t Notes 0 51 24 4 1 3 1050 1 13 24 0 1 5 350 0 91 23 8 1 7 244 0 88 23 6 1 7 252 g r e y l e a v e s 0 61 22 8 1 4 212 0 81 22 7 1 2 108 0 90 22 5 1 1 182 0 92 22 3 1 l 87 n e t t l e 0 36 22 1 0 6 390 g r a s s 0 36 22 1 0 3 405 0 3...

Page 68: ...Data i s sent as a s t r i n g o f b i t s An e x t r a b i t can be added as p a r t o f an e r r o r checking code The terms odd and even r e f e r t o how t h e e r r o r checking code works Sometimes receiving devices are s e t up t o expect the p a r i t y b i t but not use it Don t worry i f t h i s seems obscure A l l you have t o do i s ensure t h a t your AP4 and t h e p r i n t e r are t...

Page 69: ...sks may not keep up I f so a communication e r r o r w i l l be indicated P r i n t e r s are u n l i k e l y t o keep up some data w i l l be l o s t unless the p r i n t e r s i n p u t b u f f e r i s l a r g e r than t h e amount o f data being sent Jumper J3 on t h e main c i r c u i t board see below s e l e c t s whether t h e CTS handshake l i n e i s connected t o p i n 20 o r p i n 4 o f...

Page 70: ...This page i s blank Page 70 ...

Page 71: ...P 7anning 7 P L A N N X N G YOUR E X P E R I M E N T IChecks IHow many readings H Memory usage H Example plan H How t o calculate available memory Page 71 ...

Page 72: ...ration 1 Caiibrate 6 4 plate with I d a pf i l t e r papei Seiect lior lo change cup 10 3 I Are you Ready Check t h a t you know t h e f o l l o w i n g I How t o c a l i b r a t e and when U How t o record and o u t p u t t h e data I What you a r e going t o measure and why I What names you w i l l use f o r t h e experiment and t h e groups o f data I How many p l a n t s and leaves per p l a n...

Page 73: ...t a r t running o u t i n 2 t o 3 days assuming an 8 hour day See How t o ca 7cu7ate avai Table memory i f you want t o know e x a c t l y 7 3 MEMORY USAGE The memory s i z e i s 32 000 b y t e s Each reading uses 20 bytes w i t h an o p t i o n a l 0 t o 30 b y t e s overhead f o r any a n n o t a t i o n you add 1 keyboard c h a r a c t e r 1 b y t e The readings a r e kept i n groups each w i t...

Page 74: ...ack a d r i n k and a jam sandwich Battery l i f e 20 say 100 20 hours 1 This i s a b i t low better recharge battery Free memory 20 say Shou7d be OK f o r 126 readings a t least more i f I keep down the annotat ion t o a reasonable 7eve7 Someone must have 7eft in a 70t o f data from last time Do they want i t or can I delete i t now Check desiccant Blue OK but p i n k replace Check C a l i b r a ...

Page 75: ... o f data number o f experimental p l o t s f o r instance c average l e n g t h o f annotation 0 t o 30 characters Example 1 Given No notes 1 group Then Maximum number o f readings 32000 44 1597 readi ngs 1 readings every 18 seconds f o r 8 houI S Example 2 Given 30 characters o f notes per reading 1 6 groups o f readings Then maximum number o f readings 32000 16 X 44 20 t 30 625 readings 1 readi...

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Page 77: ... and output t h e data But i t takes more t o become an expert T h i s next section should help W e hope so anyway I Hints and t i p s f o r good experimental technique R Explanation o f resistance and conductance units I Barometric pressure considerations I Porometry and stomata Page 77 ...

Page 78: ...e f i r s t run o f the day Choice o f cup Leaf hand1ing Sensitive stomata The cup leaf seal Temperature management Leaf temperature Cup temperature Coping with very high resistances The l i g h t sensor Cleaning the sensor head Page 78 ...

Page 79: ...r t i n g up t h e AP4 f i r s t use i t t o measure t h e ambient RH S e l e c t t h e c y c l i n g l e v e l nearest t o t h i s RH then leave t h e instrument t o c y c l e on one o f t h e c a l i b r a t i o n p l a t e p o s i t i o n s f o r maybe 10 o r 15 minutes T h i s gives t h e cup time t o acc imatise t o t h e c u r r e n t RH During storage i t may have been q u i t e d i f f e r...

Page 80: ... t h e prospect o f making hundreds o f stomata1 measurements i n a session it i s worthwhile t o optimise your technique so t h a t you take readings as q u i c k l y as possible I t i s generally b e t t e r t o accept a reading a f t e r f o u r o r f i v e cycles even though some d r i f t i s s t i l l apparent r a t h e r than hang on f o r a possibly more accurate reading The double beep gi...

Page 81: ...umber o f o t h e r f a c t o r s As f a r as p o s s i b l e t h e r e f o r e keep t h e sensor head shaded and t h e s h u t t e r over t h e leaf pad closed I f t h e 6T can be k e p t l C you a r e doing w e l l The AP4 s o f t w a r e w i l l be a p p l y i n g i t s automatic c o r r e c t i o n anyway and can cope w i t h up t o k2 5 C You may o c c a s i o n a l l y have t o t o l e r a t...

Page 82: ...y c l e This could be t h e case f o r instance i f you wanted t o record t h e r e s i s t a n c e o f t h e t o p surface o f a hypostomatous l e a f along w i t h the much lower undersurface resistances Terminate t h e reading by opening t h e head and b r e a t h i n g on i t E i t h e r d i s c a r d t h e reading o r add a note as a reminder THE LIGHT SENSOR T h i s i s a simple sensor inten...

Page 83: ...a very s o f t brush t o dislodge t h e d i r t Scratching t h e sensor may change i t s R H c a l i b r a t i o n W h i l s t you have t h e sensor head i n pieces you can wipe t h e R H sensor w i t h d i s t i l l e d water Use a c o t t o n bud o r a t w i s t o f c o t t o n wool around a match s t i c k Be gentle The sensor s u b s t r a t e i s b r i t t l e l i k e glass I t i s glued down...

Page 84: ...Hints 6 t i p s This page deliberately blank Page S4 ...

Page 85: ...f o r r and c are By expressing concentration i n dimensionless u n i t s o f m01 o f water vapour per m01 o f a i r m01 m o l l e f f e c t i v e l y equivalent t o t h e volume f r a c t i o n vpm the u n i t s f o r r become mZ S mol I mol u n i t s E g m 2 S l m01 m 2 S CONVERSION FROM VELOCITY TO MOL UNITS OF RESISTANCE r i s i n m2 S mol 1 r i s i n S m Vo i s i n m3 m o l l t h e molar volu...

Page 86: ...t s are independent o f pressure but are weakly dependent on temperature by approximately 0 25 K You may take readings w i t h t h e AP4 i n any o f t h e f o l l o w i n g u n i t s Resistance S cm S m m2 S mol 1 Conductance cm S mm S mm01 m 2 S l 0 1 S mm 1 0 S cm 100 S m e t c The values a r e r e f e r r e d t o t h e a c t u a l cup temperature o f t h e reading and t h e pressure s e t t i n...

Page 87: ... t which t h e readings were made AN INCORRECT PRESSURE SETTING Provided that the pressure does not change i n between the c a l i b r a t i o n and taking the readings t h e resistance values w i l l not be i n e r r o r they w i l l merely be referenced t o t h e s e t pressure value The stored s e t pressure value w i l l o f course be i n c o r r e c t though FAILURE TO RECALIBRATE WHEN THE PR...

Page 88: ...r i c a l c i r c u i t f o r the l o s s o f water vapour from a l e a f by d i f f u s i o n through t h e stomata and c u t i c l e o f t h e upper and lower epidermis Reproduced W i t h perm iss ion from P r inc i p 1es o f Env ironment a 7 Phys ics by J Monte i t h pub 1ished by Edward Arno ld Page 8 8 ...

Page 89: ...monly between 10 and 30 pm and t h e area occupied by a complete stoma i n c l u d i n g t h e guard c e l l responsible f o r opening and s h u t t i n g t h e pore ranges from 25 X 17 pm i n Medicago sativa t o 72 X 42 p m i n Phy7 7 i t i s sca 7opendr ium Because stomata tend t o be smaller i n leaves where they are more numerous the f r a c t i o n o f t h e l e a f surface occupied by pores ...

Page 90: ...Technica 7 This page blank Page 90 ...

Page 91: ...assemble 10 7 Pump How t o change i t 10 8 L i g h t Sensor Calibration 10 9 R H Sensor Cal ib r a t i o n 10 10 Thermistors Calibration 10 11 Software crashes How t o reset 10 12 Trouble shooting 11 H O W I T W O R K S 11 1 What happens i n the head 11 2 How t h e r e s u l t s are calculated 11 3 How t h e electronics work 12 CIRCUIT DIAGRAMS 13 COMPONENTS CONNECTORS 14 SPARES CONSUMABLES AND AC...

Page 92: ...This blank ...

Page 93: ...el w i t h 8 l i n e s X 40 character LCD display QWERTY keypad f o r annotation RS 232 interface Pocket f o r sensor head desiccant and c a l i b r a t i o n plate Version 2 Functions read calibrate review and output automatic c a l i b r a t i o n curve f i t t i n g automatic temperature correction Choice o f units Resistance S cm l S m m2 S mol l Conductance cm S 1 mm S mm01 m 2 S Duration 20 ...

Page 94: ... and A S C I I t e x t Compatibility For use w i t h IBM PC AT XT computers Disk sizes 3 5 and 5 25 disks both supplied w i t h a l l orders OPERATING L I M I T S Temperature 0 t o 50 C Humidity 10 t o 90 RH non condensing CALIBRATION PLATE VALUES a t 20 C 1 0 0 0 hPa P1a t e p o s i t i o n Resistance I Conductance s cm s m m s rnol crn s mm s mmol rn2 s continued Page 94 ...

Page 95: ...the measurement agrees with the true value 100 is perfect as verified by comparing plate readingswith the referencevalue for a specific temperature and pressure The stated accuracy applies over the range of the calibration plate and for optimumcup conditions i e from l 0to 5 C difference betweenactualcup temp andthat existing at calibration and for 2 5to 2 5 Cdifference between leaf and cup temper...

Page 96: ...How to Service PLEASE NOTE See Appendix E AP4 BATTERY DESIGN CHANGE Page 96 ...

Page 97: ...ge i t 104 10 4 Desiccant How t o change i t 106 10 5 Eprom How t o change it 107 10 6 Head How t o disassemble 110 10 7 Pump How t o change i t 1 1 1 10 8 L i g h t Sensor Calibration 112 10 9 RH Sensor Calibration 113 10 10 Thermistors Calibration 114 10 11 Software crashes How t o reset 1 16 10 12 Trouble shooting 117 Page 97 ...

Page 98: ...P4 shows a warning SHUTTING DOWN and switches i t s e l f o f f t o ensure data memory retention f o r a t l e a s t another 2 weeks The sleep consumption when the AP4 i s switched o f f i s negligible and w i l l normally be exceeded by the b a t t e r y s self leakage The s e l f leakage i s very temperature dependent as can be seen from the maximum storage time graph which shows the time f o r ...

Page 99: ...rning completely f l a t i t may take a long and then i t may have l o s t STORAGE THE BATTERY MUST BE CHARGED BEFORE AND PERIODICALLY DURING STORAGE t o prevent deep discharge due t o gradual self leakage Recharge a l l b a t t e r i e s a t l e a s t once a year For storage temperatures above 20 C recharge more frequently See Maximum Storage Time graph which shows t h e t i m e f o r complete se...

Page 100: ...d Loosen the wing nut t h a t secures t h e b a t t e r y clamp l i f t the cjamp up enough t o c l e a r the battery then c a r e f u l l y s l i d e the battery w i t h i t s wires and connector clear When f i t t i n g the new battery simply reverse the procedure but pay special a t t e n t i o n not t o t r a p the wires under the battery clamp Feed them through f i r s t Page 100 ...

Page 101: ...hook velcro from case section i n the same manner and s l i d e the bag from the case assembly TO OPEN THE CASE Lay the case on i t s front and using a steel rule o r finger n a i l s remove the four black r i v e t s that hold the cover plate t o the back o f the case Remove the cover plate grip the ribbon cable as close t o i t s connector as possible and p u l l it clear from the case Page 101 ...

Page 102: ...nimise the exposure t o a i r Use t h e blank bung and also the bung t h e head assembly With one hand on the p l a s t i c c l i p inside the side pocket and the other on the bezel a t the other end gently ease the chassis assembly from the case Note t h a t excessive force should not be applied t o the bezel i n an e f f o r t t o remove the chassis from the case See a l s o Page 96 Once t h e c...

Page 103: ...Case 6 Chassis CHASSIS LAYOUT Page 703 ...

Page 104: ...are shipped from the factory with the s l o t installed The active cup i s p r e t t y obvious It i s the one a t the end o f the head You can see it through the sliding window The calibration plate i s designed f o r use with either cup POROMETER HEAD WITH SLOTTED CUP INSTALLED POROMETER HEAD DISASSEMBLED Showing rubber seal and cup insert CUP GR5KET u s by P the h d Page 104 ...

Page 105: ... o r shock the f r a g i 7e RH sensor Do not use organic solvents on or near the RH sensor You can now r o t a t e and replace cup i n s e r t and seal Do up t h e screws u n t i l you j u s t f e e l some resistance and then t i g h t e n up one more quarter t u r n WARNING Avoid overtightening the screws They are stronger than the p7ast i c o f the insert and may s t r i p out the thread Change ...

Page 106: ...d container It opens at one end Either replace the desiccant with fresh self indicating silica gel crystals or reconstitute the crystals see below Reassemble RECONSTITUTION OF CRYSTALS Spread out the crystals in a heatproof dish or tray Heat gently in an oven at 93 C 200 F for 4 to 8 hours until the blue colour returns WARNING Overheating crysta7s can reduce t h e i r capacity Page 106 ...

Page 107: ... end The new chip w i l l need t o go i n the same way round But before you do t h a t It i s good practice t o protect EPROMs from s t a t i c e l e c t r i c i t y as much as possible I n case your fingers are charged up discharge them by touching them onto the chassis I f you have one wrap a conductive strap around your w r i s t and earth it t o t h e chassis as shown i n the diagram I f not j...

Page 108: ...the new EPROM from i t s protective foam and place i t gently on top o f the socket Check t h a t a l l the legs are over a hole and t h a t none are going t o get bent underneath the chip when you push i t home Push i t gently home That s it You have done i t R e f i t the pump Ensure the pump i s securely screwed down you do not want t o l e t it shake i t s e l f loose Reconnect the pump and ba...

Page 109: ...EPROM CHANGING THE EPROM WELT F b w G T R T _ _ ELECTRIC T Y I I 7 c f i n l Gr hc s Do n o bed F Page 1 09 ...

Page 110: ... separated f o r changing o r cleaning the cup seal cup i n s e r t and gasket I Inspect the spring t o see how i t i s located I Push out the hinge p i n I unplug the ribbon cable Remove the spring Observe the l i g h t sensor c a l i b r a t i o n f a c t o r wr itten on the inside o f the l i g h t h a l f You can now change the cup i f you wish Chapter 10 3 To reassemble I Replace the spring I...

Page 111: ... pump i n l e t and o u t l e t pipes Unscrew the pump mounting bracket and remove the pump and bracket Unscrew the four s e l f tapping screws t o remove the pump from i t s bracket When f i t t i n g the new pump simply reverse the procedure It may help t o moisten the pump i n l e t and o u t l e t s before pushing on the f l e x i b l e a i r 1ine tubing Page 111 ...

Page 112: ...rogram the AP4 w i t h a d i f f e r e n t s e n s i t i v i t y f a c t o r should you change sensor heads o r need t o re calibrate the l i g h t sensor H Clean t h e l i g h t sensor s translucent p l a s t i c cover w i t h a damp cloth I Select t h e CONFIGURE AP4 HEAD screen by pressing the SHIFT and OFF keys together I Use the keys t o e i t h e r Set the sensor s s e n s i t i v i t y f a ...

Page 113: ... hole i n the side o f the sensor head f u r t h e s t from the cup t o give the correct indicated RH Applying a known RH i s not easy Allow plenty o f time f o r equilibration since so many surfaces absorb release water Some methods are a Blow dry bottled gas onto the sensor Separate the two halves o f the sensor head by pushing out the hinge pin b Regenerate the s i l i c a gel i n the AP4 and t...

Page 114: ...using hydrated ferrous sulphate Take care t o avoid o r compensate f o r temperature differences between the R H source and the porometer s R H sensor A s u i t a b l e generator i s the ADC WG600 humidity generator b Leave the opened sensor head i n a humidity controlled chamber REPEAT Repeat s e t t i n g t h e low and high RH u n t i l the two known s e t points can be read t o w i t h i n 0 5 ...

Page 115: ...F screen i s more than 0 5 C and t h e temperature has s t a b i l i s e d then there may be a f a u l t i n one o f the thermistors I f the Cup temperature reading i s obviously wrong check t h a t the sensor head connector i s properly plugged i n t o t h e main case and check the c o n t i n u i t y o f connection between the thermistor and the main c i r c u i t board I f these are OK the cup ...

Page 116: ...en the case Remove the ribbon cable cover plate b u t do not unplug the ribbon cable See 1 0 2 Remove the 4 screws on the base of the case and s t a r t t o slide the chassis assembly out of the case The ribbon cable length limits how f a r you can withdraw the chassis Reset the AP4 by shorting together pins 4 6 of the digital port the 10 way connector on the right of the main circuit board using ...

Page 117: ...an t re charge P O O R READINGS RH Cup temperature Temp difference PAR Conductance o r Resistance Re cal ibrate Clean R H sensor Check Cup thermistor Re zero temp difference Check Leaf thermi s t o r Clean l i g h t sensor surface Set L i g h t Factor Reading procedure Calibration procedure Check cup seal Change t o other cup size DATA LOSS OUTPUT PROBLEMS Data o r notes l o s t Can t communicate ...

Page 118: ...This page i s blank Page 118 ...

Page 119: ... i c i e n t depends on pressure and temperature I Saturated vapour pressure gradient depends on cup leaf temperature difference I Transit time depends on speed o f R H sensor I Flow chart o f c a l i b r a t i o n algorithms I measurement algorithms I H O W THE ELECTRONICS WORK I Sensor head I Main p r i n t e d c i r c u i t board I TDS 9092 computer card I Charging p r i n t e d c i r c u i t b...

Page 120: ...What happens i n the head Page 120 ...

Page 121: ...de holes o f known dimensions from which the resistance has been d i r e c t l y calculated by f i n i t e element analysis The t r a n s i t time i s found t o depend s l i g h t l y on the RH h i s t o r y w i t h i n the cup For t h i s reason it i s necessary t o repeat t h e readings using a consistent cycle o f humidification and desiccation u n t i l the conditions i n the cup have stabilis...

Page 122: ...What happens in the head A TYPICAL CYCLE Page 122 ...

Page 123: ... s i t time Wood s equation describes cup absorption Diffusion c o e f f i c i e n t depends on pressure and temperature Vapour pressure gradient depends on cup leaf temperature difference Transit time depends on speed o f RH sensor i F L O W CHARTS Calibration algor Measurement algor ithms i thms Page 123 ...

Page 124: ...t h a t t h e theory described q u i t e well t h e s e n s i t i v i t y and t h e temperature c o e f f i c i e n t s o f t h e Delta T Mark 3 c y c l i n g porometer Wood has made s u b s t a n t i a l a d d i t i o n a l c o n t r i b u t i o n s t o t h e theory o f c y c l i n g porometry He has extended t h e Monteith theory so t h a t i t can be implemented i n t h e AP4 He has a l s o mod...

Page 125: ... y of c y c l i n g porometry and t h e use o f c a l i b r a t i o n plates as an a l t e r n a t i v e t o the steady s t a t e method The next section describes t h e equations used i n t h e t h e o r e t i c a l model o f t h e pororneter R Monteith e t a 1 equations f o r resistance as a function o f t r a n s i t time I Wood s equations f o r cup absorption I Temperature and pressure depend...

Page 126: ... humidity i n time 6 t THE MONTEITH ET AL EQUATION FOR RESISTANCE W e can reorganise the above equation t o express t h e resistance r i n terms o f t h e t r a n s i t time 6 t 6 t I 4 L L r l e a f 2 L t L 6 rr2 D L i s known 7mm i s s e t the RH set p o i n t about which the porometer cycles 6 i s s e t a t 2 3XRH D i s known see below f o r an equation 6 t i s measured d i r e c t l y by t h e...

Page 127: ...nor Refinement t o t h e Monteith Equations The above two equations contain t h e factor This f a c t o r i s i n f a c t an approximation and a b e t t e r value i s given by rep1aci ng where I n denotes logarithm t o the base e Page 127 ...

Page 128: ...stants c h a r a c t e r i s t i c o f each head They are determined a t c a l i b r a t i o n time as follows Wood s equation i s used both when c a l i b r a t i n g and when taking a reading When calibrating L i s calculated f o r a l l 6 p l a t e positions from the corrected t r a n s i t times 6 t f by rearranging Monteith s equation f o r L The resistance values used are the theoretical tru...

Page 129: ...n 1 7 5 D Do Parkinson 1985 5 j F where Do i s t h e d i f f u s i o n c o e f f i c i e n t a t temperature To and pressure PO and D i s t h e value a t T and P Over t h e range 5 t o 55 C t h e following l i n e a r approximation i s adequate and i s used i n t h e AP4 P where T i s i n C and P i s i n hPa or mbar W e use equation 6 w i t h i n t h e AP4 I n chapter 8 2 i n the t u t o r i a l o...

Page 130: ...cs see f o r instance Monteith Unsworth 1990 The resistance o f the c a l i b r a t i o n p l a t e i s calculated a t 20 C a t an atmospheric pressure o f 1000 hPa mbar from the known geometry o f the pores The resistance a t other temperatures i s given by Combining t h i s w i t h equation 6 where Tcup i s i n C and P i s atmospheric pressure i n hPa o r mbar and r T i s t h e cup resistance a ...

Page 131: ...s reproduced i n chapter 8 4 t h i s assumption i s v a l i d f o r many p r a c t i c a l purposes Tables o f water vapour pressure as a f u n c t i o n o f temperature are available elsewhere L i s t RJ 1971 Smithsonian Meteorological Tables 6th ed Washington DC Smithsonian I n s t i t u t i o n Press The porometer uses the f o l iowing approximat ion from Campbe1l 1977 SVP T 10 26 exp 52 57 679...

Page 132: ...v e humidity i n the porometer cup So the flow by d i f f u s i o n o f water vapour i n t o the cup depends on the vapour pressure difference divided by the resistance I f the l e a f i s cooler than the cup the porometer w i l l record the same t r a n s i t time as from as another l e a f o f higher resistance a t the same temperature as the cup W e can therefore set up the f o l l o w i n g si...

Page 133: ...ce c a l i b r a t i o n p l a t e resistance a t cup temperature assuming no temperature gradient rcup resistance o f the porometer cup Case 2 Measuring a l e a f i e Resistance unknown I f the porometer i s measuring a p a r t i c u l a r unknown resistance a t a measured 6T then t h e resistance it would measure assuming no temperature gradient i s given by Footnote H i s t o r i c a l l y we h...

Page 134: ... time t h a t would be seen by a p e r f e c t l y f a s t sensor measured transit time R H sensor time constant a t temperature T RH c y c l i n g l e v e l t h e Set RH point RH r i s e over which the t r a n s i t i s timed Thi S equation was derived semi empi r i c a l l y assuming t h a t the r e l a t i v e humidity during a cycle i s driven 5 below the RH set point and there i s no overshoo...

Page 135: ...ected t r a n s i t time t h a t would be seen by a perfectly f a s t sensor time constant o f RH sensor time constant o f R H r i s e i n the cup time Assume t h a t the indicated minimum R H i s controlled t o set 0 05 and t h a t t 0 when i n d i s a minimum Also t h a t t h e actual RH i n t h e cup follows an exponential curve then a c t 1 A e x p t S e t t i n g t 0 when s e t 0 05 it can be...

Page 136: ...l and t n f o r values o f r TS s e t covering the range o f AP4 operating conditions and 6tm tz t1 compared w i t h 6 t f An empirical r e l a t i o n s h i p was then found which predicted 6 t f from 6tm w i t h e r r o r s less than l 0 ms over the whole range This i s the R H sensor time constant correction equation 12 6 t f atm 1 1 5 I Z exp Ia lo7 1 1 0 023 2 155 K s A graph of t h e correct...

Page 137: ...HOW the resq7ts are ca7cu7ated GRAPH OF A TYPICAL TRANSIT TIME CORRECTION Transit time correction at RH 50 25 C 0 100 200 300 400 500 600 700 800 900 1000 Indicated transit time ms Page 137 ...

Page 138: ...HOW the resu7ts are ca 7cu7ated C RLIBPRTION A L G R T W M FL UCHRRT I I I 4 L t4KRT I J READlaC RRT r i r e c E L 2 921 5 1 5b CYCLE 1 1FIT CURVE b 0 77 I J I Page 138 ...

Page 139: ...How the resu7ts are ca7cu7ated 1 MIO CUR mPcdu s LPSY I NEXT CYCLE Page 739 ...

Page 140: ...How the e 7ectronics work wan KEYPW HAIN PC0 m Page 140 ...

Page 141: ... electronics hardware works It does not explain how t o do repairs Only experienced electronics s p e c i a l i s t s w i l l f i n d i t useful E Sensor head I Main p r i n t e d c i r c u i t board I TDS 9092 microprocessor board E Charging p r i n t e d c i r c u i t board B Power supplies I Power r a i l s See also Trouble shooting table Chapter 10 12 also on the laminated p l a s t i c Quick ...

Page 142: ...e i n R H by d i f f e r e n t i a t o r IC3b Temperature difference by d i f f e r e n t i a l a m p l i f i e r IC4a b d Battery v01tage by p o t e n t i a l d i v i d e r R17 18 The signals are selected by t h e multiplexer IC6 and then measured by the 10 b i t A D converter IC5 A spare input channel Multiplexer address 6 together w i t h power supplies and a spare d i g i t a l i o p o r t are...

Page 143: ...32 9V s e r i a l outputs and i n p u t s are provided f o r sending stored readings t o a computer o r p r i n t e r Handshake i n p u t output s i g n a l s a r e avai lable i f necessary and a r e connected t o appropriate p i n s on t h e 25 way D connector by jumpers J3 J4 see Chapter 6 6 The TDS9092 connector p i n s are each numbered w i t h a lower case l e t t e r and a number eg a12 n o ...

Page 144: ...v i a IC13 The ON b u t t o n p u l l s SHDN low a c t i v a t i n g t h e o t h e r power r a i l s by t u r n i n g on TR2 and enabling IC11 and t h e MAX666 on t h e TDS9092 P o r t P52 should then go high under software c o n t r o l t u r n i n g on TR3 h o l d i n g SHDN low u n t i l t h e AP4 switches o f f The AP4 can a l s o be switched on a t a programmed time by IC14 v i a TR6 POWER RA...

Page 145: ...Circuit Diagrams Analogue D i g i t a l TDS9090 Forth Computer Charge PCB Main PCB Block Diagram Head C i r c u i t Page 145 ...

Page 146: ...AP4 Analogue Circuit Diagram Page 146 AP4 User Manual version2 l update ...

Page 147: ... l t a T D e v i c e s L f d 1 RP4 M A I N DIGITAL pcO DhTE 16 06 1938 128 Lov Rd Burvell Combridge CB5 OEJ UK 1 U Telephone OK38 7 4 2 9 2 2 Fox 0 38 7 4 3 1 5 5 DRRYN Torn I I SHEET 2 o r 2 F I L E AP4NflIN6 ...

Page 148: ......

Page 149: ... AT D e I t a T Dev i ce s M 120 Low Rd B I I Combrldglr C85 BEJ W Tclephonc B638 742922 Fox 8658 743155 BRT CWHm RECLLRTOR RP4 CHARGE PCB p m 1 D R I mt3 w ...

Page 150: ...AP4 PC5 component layout Page 150 AP4 User Manual version 2 l update ...

Page 151: ...B lock C i r c u i t Diagram Page 151 ...

Page 152: ... 1 n LEAF THERMISTOR RP4 UPPER HEAD BOARD l V LEAF PAR 2 5 volt8 supply cup tcmperature leaf temperature onalogue ground PAR I lght dlgltal ground R H output 5 volts supply head swltch vhlte screen black brown orange D P I t a T DevicesLld R P 4 HEAD C I R C U I T IP C 0 120 Lov Rd Burwe l l Cambr l dge CB5 OEJp K Telephone 8638 7t2922 Fox 8638 7tS 155 ...

Page 153: ...K 4 7K 4 7K 220R 1K 100K 100K 1K 100K 1M 100K 680K 100K 1O R 100R 100R IOOR 100R 100R 100R 100R 100R 100R 100R 100R 100R 1K 1O R 5 6K 2 2K 1O R 10R 39K 100K 1O K 1OK 68K 68K 1OK 100K 100K 5 6M l OOK 300K 750R 1OK 1O K l O O R IOOR 100R l O O R l O O R IOOR 100R 3 3K 1OK 1O R AP4 UserManual version2 1 update Page 153 ...

Page 154: ...P SKYCAP SKYCAP SKYCAP SKYCAP SKYCAP SKYCAP SKYCAP SKYCAP SKYCAP SKYCAP SKYCAP ELEC 25V SKYCAP SKYCAP CERAMIC SKYCAP MKS2 CERAMIC SKYCAP TANT 16V SKYCAP TANT 6V3 SKYCAP SKYCAP SKYCAP SKYCAP TANT 16V SKYCAP SKYCAP ELEC 25V TANT 16V SKYCAP SKYCAP TRIM CAP VC1 5 25P CERAMIC INDUCTOR lNDl 4 7mH ICs IC1 REF43GP 2 MAX666CPA 3 MAX666CPA 4 TLC27M2CP 5 AD7579JN 6 TLC7524CN 7 74HC14 8 PCF8573P 9 TLC27L4CN 1...

Page 155: ...hey 2re l i s t e d below f o r reference TLC27 1 Amplifier LMC555CM O s c i l l a t o r DRING 5082 2830 Detector Vaisala HMI518 RH Sensor M M 100k6MCOX Chamber thermi s t o r T B FB5CJ1 25A Inter PCB cable look lOOR 12k 4k7 1k 47k 470k 82k 500k 2k 1O n C0805 C0805 C0805 C1206E 0 1 p i t c h C0805 Parts l i s t f o r AP4 PC 03 R3 Top head S W 1 Switch Radia t ron 1241 1111 6 9 TH1 Thermistor M l4 ...

Page 156: ... I D C RIBBON IDC LCD PIN PIN FUNCTION I D C P i n l lower l e f t 1 1 8 D 7 2 1 7 D 6 3 1 6 D 5 4 1 5 D 4 5 1 4 D 3 6 1 3 D 2 7 1 2 D 1 8 11DO 9 l 0 RST 10 9 No Connection 11 8 A0 12 7 CE f o r LCD 13 6 RD 14 5 WR 15 4 Vee 6 t o 10V 16 3 t5V 17 2 GrouND 18 1 GrouND LCD p i n s 19 20 NC LID Membrane Keys 19 1 GrouND 20 2 ON KEY To SHutDowN 21 3 KEY EXCITE PB6 22 4 KEY EXCITE PB5 23 5 KEY EXCITE PB...

Page 157: ... 3 TRANSMITTED DATA 6 16NC 7 4 RTS HANDSHAKE I N 8 17NC 9 5 HANDSHAKE O U T 10 18 NC 11 6 HANDSHAKE O U T 12 19 N C 13 7 GrouND 14 20 DTR HANSHKE I N 15 8 HANDSHAKE O U T 16 21 N C Short t o pin1 t o Reset AP4 I n t o AP4 From AP4 I F Jumper 3 p o s i t i o n a I F Jumper 4 p o s i t i o n a I F Jumper 4 p o s i t i o n a I F Jumper 3 p o s i t i o n b I F Jumper 4 p o s i t i o n a DIGITAL PORT 1...

Page 158: ...Connectors 1 GrouND 2 t2V5 3 Spare ANalog i n p u t 4 NC 5 DAC 6 t5VAN Analog Ground Reference Voltage On M u l t i p l e x e r Address 2 DAC Output 0 2V5 8 b i t s t5V q5 30mA Page 158 ...

Page 159: ...tor Head Go button Leaf pressure pad and thermistor Head cable assembly Charge socket Calibration plate Pouch for calibration plate Glue Glue Glue Glue User manual CONSUMABLES KIT Type PCKl Calibration pad Silica gel crystals Tape Cup seal Cup insert Cup gasket Silica gel container tube Screws X 2 DETAILS Whisper 200 or AP50 3rnrn ERC X 700mrn Assorted white polypropylene grey silicon rubber white...

Page 160: ... Consumab7es OTHER OPTIONAL ACCESSORIES One barometer wristwatch type PBRI Spare sensor head type PSH1 Spare AP4 re chargeable battery type PSBl Charger f o r AP4 battery specify 240V 220V o r 110 V Page 160 ...

Page 161: ...ne year against defects i n manufacture o r materials used The guarantee does not cover damage through misuse o r inexpert servicing o r other circumstances beyond our c o n t r o l For the U K t h i s means t h a t no charges are made f o r labour materials o r return carriage f o r guarantee repai rs For other countries the guarantee covers f r e e exchange o f f a u l t y p a r t s during the g...

Page 162: ...Des ign Page 162 ...

Page 163: ...modelling the dynamic behaviour of the earlier AP3 2 dimensional f i n i t e element analysis I t a l s o describes the refinement o f the c a l c u l a t i o n o f the c a l i b r a t i o n p l a t e using 3 dimensional f i n i t e analysis cup by using o f the values elernent Page 163 ...

Page 164: ...v a r i a t i o n s i n l e a f resistance d r y a i r f l o w and sensor response time The model c a l c u l a t e d t h e RH throughout t h e c y c l e a t every p o i n t on a 0 5 mm g r i d on a section through t h e cup I n t h i s e a r l i e r design the d r y a i r was f e d i n from t h e side A t y p i c a l s e t o f RH contour maps a t d i f f e r e n t times through t h e cycle i s sh...

Page 165: ...Des ign Section through Plot of RHcontours air dealncup Leaf surface RH air out AP3 cup RH sensor Start of humidification cycle 1 AP3 cup End of humidification Page 165 ...

Page 166: ... i d e a l cup i e s t a r t i n g from a uniform RH o f 0 throughout and w i t h an RH sensor w i t h zero response time B A r e a l cup i s s i g n i f i c a n t l y slower than t h e model This appears t o be due t o the e f f e c t s o f water absorption on t h e surface w i t h i n t h e cup which was not included i n t h e f i n i t e element a n a l y s i s model H The Monteith e t a1 theor...

Page 167: ... h e sensor response time i s zero and the cup s t a r t s a t 0 RH everywhere This i s a s t r a i g h t l i n e Predicted by the model cup with a i r f l u s h i n g v e r t i c a l l y and R H sensor w i t h f i n i t e response time A i r f l u s h i n g horizontal l y and RH sensor w i t h f i n i t e response time Test data from a Delta T AP3 porometer 0 0 5 1 0 L5 2 0 23 3 0 3 5 4 0 Transtt...

Page 168: ... x a c t l y match t h e geometry o f t h e actual c a l i b r a t i o n p l a t e and cup combination which consists o f a row o f pores d i f f u s i gi n t o a rectangular s l o t W e have t h e r e f o r e modelled t h e c a l i b r a t i o n p l a t e using f i n i t e element analysis A commercial f i n i t e element analysis program was used LUSAS F i n i t e Element Analysis Ltd London Thi...

Page 169: ...l R d Qnl s rr D Rd i s t a k e n from a t a b l e and d e p e n d s on t h e r a t t o of r t o S D I s t h e diffusion r e s l s t a n c e R I s Independent o f l I f l S A p a r t of t h e Delta T caUbratlon p l a t e and cup geometry used In t h e Flnlte Element Analysls Page 169 ...

Page 170: ...Des ign TYPICAL RH CONTOUR MAP CALCULATED BY F I N I T E ELEMENT ANALYSIS Used i n calculating calibration plate resistance Page 17G ...

Page 171: ... i s I Independent t e s t comparison o f version 1 o f the AP4 t h a t i s without temperature correction with our previous model t h e Mark 3 porometer P Experimental basis f o r the AP4 version 2 temperature correction algorithms Page 171 ...

Page 172: ...easurements were g e n e r a l l y made on t h e younger mature leaves beginning w i t h t h e youngest l e a f which would f i t t h e porometer but i n pidgeonpea some measurements were made on o l d e r leaves Consecutive measurements were a l t e r n a t e d between using the Mark 3 and AP4 f i r s t t o avoid i n t r o d u c i n g any systematic b i a s A wide range o f conductances was obtai...

Page 173: ...e r r e s p e c t i v e l y t o the lower and upper surfaces o f l e a f 1 2 t h e f i r s t and second mature leaves numbered from t h e stem apex The dashed l i n e s represent 10 d e v i a t i o n s from an i d e a l 1 l r e l a t i o n s h i p s o l i d l i n e 0 25 0 5 0 75 1 OO 1 25 1 50 1 75 2 00 2 25 AP4 cm S Reproduced with t h e k i n d permission o f t h e D i r e c t o r ICRISAT Hydera...

Page 174: ...Des ign APPARATUS USED I N TESTING THE AP4 ALGORITHMS Page 174 ...

Page 175: ... l a r fashion F i r s t Wood s equations f o r L the cup parameter and 6 t f the corrected t r a n s i t time were refined and developed along w i t h t h e r e s t o f the algorithms outlined i n chapter 11 2 f o r c a l i b r a t i n g and taking readings Porometer head cups were exercised through a representative range o f RH cup temperature and leaf cup temperature differences t o validate t ...

Page 176: ...e and cup leaf temperature d i f f e r e n c e I t also sent t h e resistance as calculated using t h e Mark 3 porometer type c a l i b r a t i o n process implemented i n version 1 o f t h e AP4 This resistance was measured by i n t e r p o l a t i n g from a c a l i b r a t i o n curve f i t t e d by the method o f l e a s t squares t o t h e set o f s i x p a i r s o f t r a n s i t time and re...

Page 177: ... o f data P l o t t e d on log log axes they are close t o a s t r a i g h t l i n e so they can be characterised by a quadratic curve The c a l i b r a t i o n r o u t i n e t h e r e f o r e f i t s a quadratic curve t o these p o i n t s on t h e log log graph This graph i s then used t o c a l c u l a t e an appropriate value o f L when t a k i n g a reading The curve t y p i c a l l y has a s...

Page 178: ... i o n curve This graph i s included t o reassure those f a m i l i a r w i t h t h e Mark 3 Porometer W e include it here because you can t h i n k o f graph 1 as being t h e c a l i b r a t i o n curve i n t h e AP4 o f L vs 6 t Whereas the e a r l i e r models t h e Mark 3 and version 1 o f t h e AP4 used graph 2 as t h e c a l i b r a t i o n curve 5000 10000 Transit time rns Page 178 ...

Page 179: ... and the porometer reading logged From these readings and t h e known value o f t h e resistance L was c a l c u l a t e d f o r each reading These values were normalised using t h e c a l i b r a t i o n curve graph 1 t o t h e equivalent constant value o f 6 t 1000ms The r e s u l t s show t h e temperature dependent p a r t o f L f o r a t y p i c a l s e t o f data This gives the temperature d...

Page 180: ...match the known p l a t e values i s a measure o f t h e success o f t h e algorithm i n i t s a b i l i t y t o c o r r e c t f o r deviations from t h e cup temperature e x i s t i n g a t c a l i b r a t i o n Whilst o n l y two p l a t e p o s i t i o n s are shown here f o r one p a r t i c u l a r s e t o f conditions we f i n d i t t o be t r u e f o r the r e s t o f the combinations o f p...

Page 181: ...o f the c a l i b r a t i o n plate varied r e l a t i v e t o t h a t o f t h e cup using a P e l t i e r e f f e c t heat pump I n t h i s graph the ideal cor rection i s drawn as a horizontal s t r a i g h t l i n e f o r both resistances Again w h i l s t we do not present a s t a t i s t i c a l analysis inspection shows t h a t the correction i s very good Delta T correction Calibrated at RH...

Page 182: ...over t h e range l 0 t o 5 C f o r cup temperature and 2 5 C f o r cup leaf temperature d i f f e r e n c e away from t h e c o n d i t i o n s e x i s t i n g a t c a l i b r a t i o n I t i s important t o r e a l i s e t h a t t h i s accuracy w i l l be compromised by poor c a l i b r a t i o n I t may w e l l be b e t t e r than t h i s using a c a r e f u l c a l i b r a t i o n Page 182 ...

Page 183: ...ysis o f the D i f f u s i o n Porometer Agricu7tura7 Meteoro7ogy 23 9 20 Monteith J L Campbell G S Potter E A 1988 Theory and Performance o f a Dynamic D i f f u s i o n Porometer Agricultura 7 Forest Meteorology 44 27 38 Monteith J L 1980 Principles o f Environmenta7 Physics Arnold London Meidner H Mansfield T A 1968 Physiology o f Stomata McGraw H i l l London J a r v i s P G Mansfield T A 1981...

Page 184: ...Calibration summary 56 Carbon dioxide 89 CASE A N D CHASSIS 101 CHANGING THE CUP 105 CHANGING THE SETTINGS 30 Chapman and Parker 168 CHARGING PRINTED CIRCUIT BOARD 143 CHASSIS LAYOUT 103 CHECKS 72 C i r c u i t diagram analogue 146 block 151 Charge PCB 149 d i g i t a l 147 Forth computer 148 Head PCB 152 main PCB 150 TDS 9090 148 CLEANING THE SENSOR HEAD 83 COM2 63 Comma Separated Values 64 Commu...

Page 185: ... i t time 122 134 6tm measured t r a n s i t time 122 134 Data b i t s 68 Data format 64 DEBUGGING 117 DESICCANT H O W T O CHANGE I T 106 DESIGN OF THE AP4 163 Double beep 80 E l e c t r o n i c s How i t works 141 EPROM H O W TO CHANGE I T 107 Equations 123 E r r o r 54 EXAMPLE PLAN 74 EXIT KEY 18 EXPERIMENTAL BASIS FOR THE AP4 ALGORITHMS 175 FAULT FINDING 117 Ferrous sulphate 114 F i c k s law o...

Page 186: ...7 4 J u m p e r s 6 9 KEYBOARD 1 6 L c u p l e n g t h p a r a m e t e r 177 LEAF HANDLING 8 0 LEAF TEMPERATURE 8 1 L e a f name 3 2 L i d ribbon c a b l e 1 5 9 LIGHT SENSOR 8 2 LIGHT SENSOR CALIBRATION 112 L i q u i d c r y s t a l d i s p l a y 1 5 9 MAIN PRINTED CIRCUIT BOARD 142 M a r k 3 p o r o m e t e r 172 1 7 8 MEASUREMENT 2 8 Memory 1 0 MEMORY USAGE 7 3 Memory How many r e a d i n g s t...

Page 187: ...UT 33 PRINTER WON T PRINT 66 PRINTING DIRECT TO A PRINTER 66 Protection 10 PUMP H O W TO CHANGE I T 111 Pump Assembly 159 QWERTY keyboard 16 Quick Guide 25 READ 29 READING CYCLE 34 READING LOOP 30 READINGS CYCLE SCREENS 35 READINGS SETTINGS SCREEN DISPLAY 32 RECONSTITUTION OF CRYSTALS 106 REFERENCES 183 REPAIRS 117 141 RESISTANCE CONDUCTANCE UNITS 85 Resistance High 82 RETRIEVE 2 63 REVIEW 57 RH c...

Page 188: ...MICROPROCESSOR CARD 143 TECHNICAL SECTION 91 Temperature c o r r e c t i o n algorithms 138 v a l i d a t i o n 175 180 Temperature dependance o f cup water absorption 179 TEMPERATURE MANAGEMENT 81 Temperature c o r r e c t i o n 123 TEST RESULTS 171 172 175 Text 64 Theory 121 123 Theory RH sensor 134 saturated vapour pressure 131 vapour pressure gradient 132 Thermistor 14 115 Time constant 134 Tr...

Page 189: ...Index WHAT HAPPENS ON Y O U R COMPUTER SCREEN 64 Wiring connectors 156 WOOD S EQUATION F O R CUP ABSORPTION 128 Wood s equations f o r L 175 Page 189 ...

Page 190: ......

Page 191: ...have an RS232 port but does have a USB port you must obtain a USB to RS232 adapter suitable for your version of Windows TO INSTALL THE SOFTWARE From the floppy disk Read the Readme txt file on the floppy disk This may contain more recent important information that you should comply with Then Run A Setup exe From a website download Run the downloaded exe executable file TO RUN THE AP4 RETRIEVE SOFT...

Page 192: ...APPENDIX C Page 192 AP4 RETRIEVE for WINDOWS ...

Page 193: ...APPENDIX C AP4 RETRIEVE for WINDOWS Page 193 ...

Page 194: ...APPENDIX C This page is intentionally blank Page 194 AP4 RETRIEVE for WINDOWS ...

Page 195: ...iety of field situations The main features are highlighted below The new mouldings are immediately recognisable from the finger grip mouldings and the Delta T name New tooling has been produced to increase the consistency of manufacture of the cup and leaf pad gaskets and seals The functionality of the AP4 head is not changed and it will show increased life and durability in field use Finger grip ...

Page 196: ...APPENDIX D This page is intentionally blank Page 196 AP4 head Design Detail ...

Page 197: ...n of various internal components is changed as illustrated below When referring to section 10 1 BATTERY from page 98 you should interpret the instructions taking into account the new physical arrangement The instructions regarding operating care and maintenance of batteries remain the same New battery position Pump new position Original battery position Pump original position AP4 Battery Design Ch...

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