IJ Instruments Ltd. IJ-6 SOFTWARE
Contents
1. box with the voltage reference applied and divide by the voltage reference in mV For example suppose the ADC zero value with the thermocouple connector shorted is 16075 When a 50mV reference is connected the ADC reading is 39836 The ADC gain is therefore 39836 16075 50 475 22 bits mV 11 MISCELLANEOUS 11 1 DISCONNECTING THE CONTROLLER If the controller is accidentally switched off or disconnected the software may display an error message similar to that shown in Fig 35 and will then quit Ensure the controller is reconnected properly and switched on then restart the software Project1 A Run time error 8021 Internal error retrieving device control block for the port Fig 35 Error message shown on disconnect 11 2 MAXIMUM RECORDING TIME LIMIT The internal variable used to determine the time of the entries in the log file has a maximum value of approximately 25 days and then rolls over to zero This may cause problems if data is recorded continuously for greater than 25 days 31 11 3 HEAVY CPU USAGE Although the software makes use of timing functions and does run slower if CPU usage is high this should not affect the degree of temperature control in any way Fig 36 shows an example of this high CPU usage causes large fluctuations in the calculation cycle time but this does not affect the temperature 100 oO D Da 23 50 a a 0 0 100 200 300 400 500 600 700 2 2 2 0 18 5 16 2 12. 22 Y Time Td 4 125 Ambient temperature Process temperature la Setpoint temperature Dutput power Load file Clear file Seo Geer Not logging Setpoint amp program control Relay 1 Graphical display Manual setpoint 60 Manual C Temperature Programmed ON OFF Min process Max process aa Greater than y 30 o y less than Zj 0 Min ambient Max ambient x les Pixel size Relay 2 samples ixel size Start Stop Hold Manual Temperature C Programmed ON Reset Process 38 24 Greater than v 100 y flessthan y 26 Ambient 22 46 Fig 3 Main screen shown after recording some temperature data 6 2 2 HOW TO ENTER DATA Several parameters in the program are entered in the blue coloured boxes The behaviour of these is slightly different from a normal entry box The process is shown in Fig 4 Click on the value to be changed The box will turn red and you can enter a new numerical value in the red box as you would normally To accept the new value press Return or Enter when the cursor is in the box The box turns back to blue with the new value present If you change your mind and don t want to accept the new value press the Escape key when the cursor is in the red box It will leave the value in the blue box unchanged Kp 4 N Click on box to change Kp E 1 Box turns red Kp 10 Enter new value Kp 10 Press Return or Enter N to set new value Fig 4 E
3. So for example at 10 C the TC voltage is about 60uV higher than actual Thermocouple voltage offset uV relative to true value 20 10 0 10 20 30 40 50 Ambient temperature C Fig 37 Thermocouple offset error vs ambient temperature 0 20 oO o 0 15 9 Z T 0 10 a2 50 2 gt 0 05 0 0 eE E 0 00 vo 2 So 2 0 05 5 amp O 5 xe 0 10 ES O 0 15 oO ao 0 20 20 10 0 10 20 30 40 50 Temperature C Fig 38 Thermocouple magnitude error vs ambient temperature 12 PRODUCT DISPOSAL INSTRUCTIONS The symbol shown here and on the product means that the product is classified as Electrical or Electronic Equipment and should not be disposed with other household or commercial waste at the end of its working life The Waste of Electrical and Electronic Equipment WEEE Directive 2002 96 EC has been put in place to recycle products using best available recovery and recycling techniques to minimize the impact on the environment treat any hazardous substances and avoid the increasing landfill When you have no further use for it please dispose of the product as per your local authority s recycling processes Business users should ensure that this product is not mixed with other commercial waste for disposal 33 13 CONTACT SUPPORT Dr Lindsay Robert Wilson IJ Instruments Ltd 73 Harburn Road West Calder West Lothian EH55 8AT UK Web http www eyejayinstruments com E
4. Downloads page of the IJ Instruments website at http www eyejayinstruments com or from FTDI s driver page at http www ftdichip com Drivers VCP htm If downloading from FTDI s site choose the link under Available as setup executable The installation program is called CDM _ Setup exe where the asterisks refer to the version number Run the program it may have to be double clicked twice and driver installation should proceed automatically Accept any Windows messages which may appear Once the driver has been installed connect the 1J 6 controller using the supplied cable and switch on by pressing the switch at the rear of the unit The Found New Hardware message may appear wait for this to finish and say Your new hardware is installed and ready to use or a similar message The controller has now been recognised by the computer 6 1 2 CONFIGURE PORT With the controller connected go in to Device Manager This can be accessed most quickly by entering devmgmt msc into Start Menu gt Run Windows XP or Start Menu gt Search box Windows Vista and 7 and pressing Enter In Windows 8 enter devmgmt msc into the search box on the Start screen Under Ports COM amp LPT double click on the port corresponding to the temperature controller to bring up its properties If unsure which port to choose switch the controller off and see which port disappears and then switch it back on Go to Port Settings
5. EE AEAEE AESA chug AE EEE AA EE BERAE NEARE 9 7 PIDO TACO Y cisco ada cata 9 7 1 PID EQUATION lt cctsicecscerssenenezisessxenindnentedtontsehixencnagssenssehisanensdisenssqniangncvahssdsexauiagnsnndsannsseniagacnndeasaragaes 10 7 1 1 Proportional P Control sisariensa iaaiaee EAEn EERE E EKERN E 11 7 1 2 Proportional Integral PI Control oooonnnnnccccnnnncccnnnoccncononnnncnnnancnnnnnncononnnnno conan cnn nono ncncnannncncns 12 7 1 3 Proportional Integral Derivative PID Control oononcccnnnoccccnonccocononccnnononcnonononcnonononcncnanancnnnns 12 7 2 TUNING sigs ssaps cape cegwe se enwnenadensd aan A E E T 13 a duueashs S E E A A 13 AS O ON 14 7 2 3 Summary Table of Tuning Factors cooocccccnnococcnonccnnnnnoncnnonancnoconnnnnncnnnncnnnnnnnnncnnnnnnnnnnnncncnnnnncnnns 17 B Hardware A cscovaesuessubsansevuossvaes cdscuaceusasussoubscaseevsesdsseudbscesevaescesevbtecsssvbeavers 18 8 1 Ram PAMmel ronda cias eii 18 8 1 1 JUSB CONNECTION miccional asada cede cian cesante caco 18 8 12 TXD RXD IONdicatorS ii A A AAA See el AAA s 18 A SN merine ii saie aiaia eaka Ene E S rie aeaiaioe kist 18 8 2 PRONE PAM l iii A oiae iina AAA AAA AEE a da gp du eee sda haus EEE 18 8 2 1 General Purpose Relay OUtPULS c ccccccccsscessseeecccesssesneeeeecceeseeeeaeeeeceeesseeaeeaeeeeseeeeeaaeeeeeeeeses 18 8 2 2 Main Solid State Relay OUtpUt ccoonooocccnnccnocooonoccnnnccnnnnnnnnnnnnnccnnnnnnnonnnncncnnnnn Eiai ani aitaa aiiai 19 8
6. gt Advanced and you should see a window similar to that in Fig 1 From the drop down list to the right of Latency Timer msec select 1 Ignore all the other settings Click OK and close the various windows which are still open The port is now properly configured Advanced Settings for COM4 COM Port Number x K USB Transfer Sizes Cancel Select lower settings to correct performance problems at low baud rates Defaults Select higher settings for faster performance Receive Bytes 4096 Transmit Bytes 4096 BM Options Miscellaneous Options Select lower settings to correct response problems SE Prin Latency Timer msec Gu Serial ter Cancel If Power Off meone Event On Surprise Removal Minimum Read Timeout msec Set RTS On Close E E E E E K Minimum Write Timeout msec Disable Modem Ctrl At Startup Fig 1 Port settings dialog 6 1 3 INSTALL CONTROL SOFTWARE Next install the temperature control software An installer called Temperature control software v1 3 setup exe or similar is available either on the enclosed CD or from the Downloads section at http www eyejayinstruments com Run the installer program Again accept any Windows messages which may appear Once installed an entry will appear under Start Menu gt Programs as usual 6 2 SOFTWARE CONFIGURATION 6 2 1 RUNNING THE CONTROL SOFTWARE When first run the user is presented with the splash screen shown
7. in Fig 2 Ensure the controller is connected and powered on then click Search for devices If the controller is found the associated COM port and the controller s serial number will be shown in the list If no controller is found try switching the controller off and on and searching again Click on the device to use and click Use selected The splash screen will disappear and the main control screen appears Fig 3 The device s serial number is shown in the window title bar The program automatically reloads the previous settings if used saving the user having to reconfigure the program every time it is run The values displayed both on the graph and in the indicators are updated approximately every second so there may be a small delay before the program responds to user input Temperature control software v1 1 For use with the 1J 6 controller http www eyejayinstruments com Temperature control software v1 1 About Port Serial number COM14 06 8Z8Y23Uw0 Search for devices Fig 2 Splash screen Temperature control software v1 1 Device serial number 06 BZ8Y2 3UWO Power control a Off Cycle time s 9 455 v gt Bi le C Manual 0 Update Process Ambient ADC settings Setpoint Zero 16104 lt Update Gain 472 94 bits m Samples 1000 Power Thermocouple type gt Logging PID parameters Use GS factors Dutput file Browse Kp 30 r 6 Skip values 1 Ti
8. or down from the start temperature of the current segment to the start temperature of the next segment If the start temperatures of the current and next segments are identical then the temperature is held constant Segment duration The time in minutes for which the segment lasts To stop the program at the beginning of the current segment enter zero duration Control code This is used to control the relay outputs and or to pause the program The control code is calculated by adding up the numbers corresponding to each desired operation listed in Table 3 Table 3 Program control codes Code Operation 1 Turn relay 1 on 2 Turn relay 1 off 4 Turn relay 2 on 8 Turn relay 2 off 16 Pause program For example if the user wants to turn relay 2 on and pause the program the control code is 4 16 20 The operations if any defined by the control code are performed at the start of the current segment If no operations are desired the control code is O Looking at the program we can analyse its behaviour Segment 1 Temperature is held constant at 40 C for 10 minutes 28 Segment 2 The control code is 1 so relay 1 is turned on Temperature rises to 70 C over 15 minutes Segment 3 The control code is 2 so relay 1 is turned off Temperature remains constant at 70 C for 5 minutes Segment 4 The control code is 20 4 16 so relay 2 is first turned on then the program is paused and waits for
9. such a file is shown in Fig 29 Each line should contain the process temperature in C and the critical gain amp oscillation period at that temperature separated with commas For example in Fig 29 K 10 deg and T 22 7s at a temperature of 60 C The temperatures must be presented in increasing order P 1J 7 Gain Schedule txt Notepad File Edit Format View Help 40 22 0 29 2 60 26 1 26 6 80 26 8 25 9 100 28 0 24 9 120 28 3 25 1 Fig 29 Example of a gain scheduling file The temperature range covered by the entries in the file should cover the expected operating temperature range of the controlled system Based on the file entries the software performs linear interpolation to determine K and T at the current process temperature then uses a set of factors to calculate suitable values for the PID parameters Kp T and Ty 26 Click Load file and select the gain scheduling file to use Gain scheduling can be enabled disabled using the checkbox The factors used to calculate K T and Tg can be entered under GS factors See Table 2 page 17 for a list of factors The Reset Integral button can be used to manually re zero the PID integral term This can sometimes be useful if T has been changed by a large amount or if the manual setpoint has suddenly changed both of which will cause a large fluctuation in the integral term 9 7 SETPOINT AND PROGRAM CONTROL Setpoint amp program control Ma
10. the user to resume After resuming the temperature falls to 60 C over 5 minutes Segment 5 The control code is 8 so relay 2 is turned off Since the segment duration is zero the program stops To use a program load it by clicking the button and then click Start When running the current segment is displayed The program can be stopped or paused at any time by clicking Stop or Hold To resume a paused program click Start again 9 8 RELAY CONTROL Relay 1 Manual Temperature C Programmed ON OFF Greater than v 30 lor y less than 0 Relay 2 Manual Temperature Programmed ON OFF 2 Less than v 0 and y less than 0 Fig 33 Relay control The user can control both of the general purpose relay outputs for hardware details see Section 8 2 1 Three operation modes are available manual temperature or programmed Manual In manual mode the relays can be controlled by clicking the appropriate on off buttons for each Temperature The relays are controlled depending on the current process temperature For example if we wanted relay 1 to be on when the temperature is between 50 C and 100 C the drop down lists and boxes should be configured to read Greater than 50 and less than 100 Alternatively if we wanted the relay off between 50 C and 100 C and on everywhere else we would choose Lessthan 50 or greaterthan 100 Programmed The relay outputs are placed under progr
11. tuning method As shown in Fig 12 the critical gain and period do not depend appreciably on the final power chosen in the tuning method Stepping to a value in the region of 60 100 is adequate 15 28 27 O o E 26 o D o 25 eS lt 24 23 20 40 60 80 100 Final power Fig 12 Critical gain and period versus final power used in open loop tuning Open loop tuning is sometimes quicker since only one measurement is needed but does rely on achieving a stable initial temperature Closed loop tuning is more reliable but does require some trial and error to determine an optimum value for the critical gain Choice of which method to use is left entirely to the user 16 7 2 3 SUMMARY TABLE OF TUNING FACTORS Once the critical gain and period have been determined using either tuning method suitable values for Kp Tj Tg can be calculated using the multiplying factors listed in Table 2 Various control schemes are listed differing in the degree of control they provide Ziegler Nichols is very common and provides quite a rapid response However this can cause some overshoot especially with fast changes in setpoint Tyreus Luyben provides a softer more stable response for systems which have fixed or slowly varying setpoints Table 2 PID tuning factors Control scheme K K T T T T P 0 5 5 PD 0 6 a 0 125 ST lt vo 2 Pl 0 45 0 85 N 2 PID 0 6 0 5 0 12
12. values of T will result in more severe faster integral action Fig 8 shows an example of proportional integral control for three different values of T Temperature C Proportional only K 3 0 50 100 150 200 250 Time s Fig 8 Proportional integral control Setpoint stepped from 20 C to 60 C indicated by the dashed line When T 100s droop is completely eliminated by around 200s This would be an acceptable value of T to use for a Pl controller A larger value T 150s results in an excessively long response time With a smaller value for example T 40s the controller attempts to remove the droop too quickly and the temperature overshoots the setpoint before settling down Just as too large a value of K can cause oscillations so can too small a value of Tj For most temperature control systems proportional integral control is sufficient since it results theoretically in a temperature equal to the setpoint temperature However a faster response can sometimes be achieved by adding the derivative term 7A 3 PROPORTIONAL INTEGRAL DERIVATIVE PID CONTROL With all three terms included the equation becomes K ft d PV e daa y A Kola 12 The addition of the derivative term slows the rate of change of heater power For example if the temperature is below the setpoint and increasing rapidly the derivative term is negative and results in a decrease in the applied power which in turn helps to slow d
13. 0 Time s Fig 10 Example of closed loop tuning Setpoint stepped from 20 C to 60 C each time 7 2 2 OPEN LOOP An alternative tuning method is based on measuring the temperature profile as the heater power is stepped between two values The process temperature should first be brought up to a value near the desired tuning point and allowed to stabilise This can be done either by applying a fixed power and waiting until a steady state temperature is reached or by using extremely conservative Pl only control which can be much faster For the IJ 7 demo module suitable Pl parameters are K 3 T 40 Note that PID control is less useful because of the noise introduced into the recorded power reading by the derivative term making it harder to determine the initial power level Once the temperature is stable the power is increased by a certain amount The actual amount is not critical but should be enough that a clear noise free temperature profile is obtained If desired several different increases can be tried and the results averaged Once the temperature has risen past the curve s point of inflection maximum rate of rise the controller can be switched off If Pl control was used to stabilise the temperature initially power can be increased by switching to manual power control and entering a suitable value Fig 11 shows an example of the process The temperature is initially held at 60 C using Pl only control K 3 T
14. 2 3 Thermocouple Ground Reference ooooooccccccconoooooccnnncconnnanoncnnnncononnnnnonnnnncnnnnnn ono nnnnnncnnnnnnnnnnnnncnnnnns 20 3 2 4 Status Indicators aiii 22 8 25 Thermocouple Input id dla 22 9 SoftWwareReterenca iii tds 22 9 1 Power Control noi ide 22 9 2 AD GSCI Sica taa a do ad de id da Mactan cette 23 9 3 Current Value Display iii ii iaa ea andes hd na eis eh RRA Ra eis ta Noah 24 9 4 TNELMOCOUPIE TY Pe scat ait seleceechcts coe E din idad eat 24 9 5 LOG SUN See eck ets ions AN 24 9 6 PID Parameters and Gain SCHEdUIING ccccecccssssssececccccsseesnseeeccecesseesneeeeeeceeeeceeaseeeeeeeeeseeeaaaeeeees 26 9 7 Setpoint and Program COntrol ccccccccccccsscsssseccccccsseesseeeececessessseeeeecesseeeeeeaeeeeseeseeeaeeeeeesseeeeages 27 9 8 Relay Controlan id A A A A ape ntaces 29 9 9 Graphical Display a AAA A A ARANA 30 10 Cal A a A e es Bik O a daaes 30 TOT A ON S sevt ba EE EAEE 31 10 2 ADC scsi ee wie AO ee et A GRRE Mi ARE Aline eet dh E ee aber 31 11 Miscellan OUs e re aaa area AR E E E E a EEEa a TAE prs evbaniyserenyecevtantvees ariel 31 TT Disconnecting the Controlar a A A e aa Tek ceed aiia betes eee 31 11 2 Maximum Recording Time Limit coonooooconnnccnonnnonancnonoconananonnnnnnnconnnnnnnnnnnnnnnoncononnnnnnccnnnnanonnnnnnnos 31 11 3 Heavy CPU Age iii A A a inde 32 11 4 Operating Temperature VariatiOns ccccccccsseeeeeeeeeeceeeeeeeeeeeeeeeeaaeeeeeeeeeeeeaaaceeeeeeeeeeauaaeeeeeeeeeneas
15. 32 12 Product Disposal INStructiONnS ccccccccccccscsssscecccccssssssseeeccessssseseeeeeeecssseesaaeeseceeeeeseeaaeeeeeeseseeenaaeaeeees 33 13 Contact PO A a ad Att ina 34 14 Revision Histo Yesenia tetanie rea aiia a a NE Eka aaa 34 2 INTRODUCTION amp SPECIFICATIONS The IJ 6 temperature controller provides a means of controlling many temperature processes through a computer based interface Unlike many PID controllers which are self contained and can be inconvenient to program the lJ controller is entirely software based giving greater flexibility and ease of use Log files temperature programs gain schedules and a graphical display are all readily available through the software Specifications Power Self powered USB Input connector Miniature thermocouple socket Input voltage range 30mV to 80mV Thermocouple type E J K N T limited only by software Voltage resolution 2uV Temperature resolution Type E 0 03 C TypeJ 0 04 C Type K 0 05 C Type N 0 06 C Type T 0 04 C These are the temperatures equivalent to the voltage resolution Actual resolution and accuracy will be limited by the choice of thermocouple and may be greater Ambient temperature resolution 0 03 C Outputs Variable duty cycle SSR drive 11V 40mA max Two general purpose SSR outputs SOV 0 2A max Software features Display of process ambient and setpoint temperatures File logging of all variables Graphical temperature display Programma
16. 4 2 1 2 O 1 0 AN T T r 0 100 200 300 400 500 600 700 60 5 2 Do O S 60 0 E o F 595 0 100 200 300 400 500 600 700 Time s Fig 36 Immunity to high CPU usage watching four YouTube videos simultaneously listening to streaming radio and converting an HD video file 11 4 OPERATING TEMPERATURE VARIATIONS The controller is supplied calibrated at an ambient temperature of 20 C Operation at other temperatures will result in a very small error which consists of both an offset and a magnitude error The offset error is shown in Fig 37 At lower temperatures the thermocouple voltage as measured by the controller will over estimate the true voltage and vice versa at higher temperatures The corresponding error in temperature depends on which type of thermocouple is connected As an example the 60uV error shown at 10 C in Fig 37 would correspond to a temperature error of about 1 5 C for a K type thermocouple sensitivity 40uV C The magnitude error is shown in Fig 38 as a percentage of the actual thermocouple voltage For example at 10 C the error is about 0 1 This means that if the actual thermocouple temperature was 100 C the measured temperature would be 100 1 C ignoring the offset error If prolonged operation at a temperature significantly different from 20 C is intended the controlled should be recalibrated at the intended operating temperature for maximum accuracy 32 Assumes calibration at 20 C
17. 40 From a graph of the power this corresponds to an initial heater power of 15 8 At time t Os the heater power is stepped to 60 and the temperature starts to rise At t 24s the temperature is rising at a 14 maximum rate R of 0 506 C cae tangent line is drawn at the point of maximum rate and the time of its intersection with the original steady state temperature measured In Fig 11 this lag time L is 6 6s Instead of drawing a tangent line and measuring the lag time graphically it can be calculated from 2 rez a mte R L tmax where tmax is the time at the inflection point Tmax is the temperature at the inflection point Ti is the initial steady state temperature and R is the maximum rate of rise measured at the inflection point 2 E 3 ES f E ha E io a Temperature C Rate Time s Fig 11 Example of open loop tuning showing temperature rate and power versus time Rate is the derivative of the temperature curve The critical gain and associated oscillation period can be calculated from the maximum rise rate and lag time using 2AP K and T 4L RL AP is the absolute change in heater power during the step In this example the power was increased from 15 8 to 60 so AP 44 2 Using the values of R 0 506 C s and L 6 6s we can calculate K 26 5 deg and T 26 4s These values are very close to those obtained from the closed loop
18. 5 b c PI 0 31 2 2 gt 0 g 3 PID 0 45 22 0 16 P 0 5 gt 2 2 Pl 0 5 0 45 5 PID 0 25 0 5 0 12 Pessen Integral 0 7 0 4 0 15 p Rule 2 Some o 0 33 0 5 0 33 Overshoot No 0 2 0 5 0 33 Overshoot A major advantage of calculating K Ti Ta using the factors from Table 2 is the possibility of varying the parameters depending on the current process temperature a process called gain scheduling If a list of values of the critical gain and period at different temperatures is known Kp Tj Ty can be calculated at any temperature by using the factors Although it can be time consuming to measure the critical gain and period over a range of different temperatures it can sometimes result in greatly improved control especially when the system is operated over a wide temperature range 17 8 HARDWARE REFERENCE 8 1 REAR PANEL O e bg O O RXD O TXD Power O USB Fig 13 Rear panel view 8 1 1 USB CONNECTION Connect either directly to a computer or to a powered USB hub Do not attempt to connect to an unpowered hub as the hub will be unable to supply sufficient power to the controller 8 1 2 TXD RXD INDICATORS These two LEDs indicate the flow of data between the computer and the device as follows RXD red data received by the device from the host computer TXD green data transmitted by the device to the host computer 8 1 3 POWER SWITCH Turns the device on or off Illuminate
19. IJ Instruments Ltd IJ 6 SOFTWARE BASED TEMPERATURE CONTROLLER USER MANUAL AND REFERENCE MANUAL VERSION 1 3 FOR SOFTWARE VERSION 1 3 AND HARDWARE REVISION C 1 TABLE OF CONTENTS 2 Introduction amp Specifications 0 0 ceecessseeeeenceeeeeeneeeeeeeneeesenaneeesenaeeeseeaaeeesesaaeeesesaeeeseeaaeeesenaeeeesenaeeeeneaaees 4 A 4 A O 5 5 We Demo Module lt ssnsiccetsaciscvexsassoushs cien totedhsvnstansssustexssns acsevdeasvssans aehsantvdvsseuets ctasdacextavedtentercstavasecdeexseces 5 6 Installation and Configuration ccccecseeeeeeeeeeseeneeeceeeneeesenaeeeeeeaeeeeeeaaeeeeesaeeeeeeaeeeseeaaeeesenaeeeeseneeeeneaaees 5 6 1 Software lnstallatiomivinccctevi cctescdeccenevdocides chevcees cono Eso aa EEEE E a Erer 5 6 1 1 Install Serial Port Diver vcccedecine sceseed dace etestecuenscreesaeativvasie OO 5 6 1 2 Configure Port c i id iis hid ied av Adee pe ened a tera eave ed dees eed eens eae 6 6 1 3 Install Control SoftWare me cocoa circa nd naaa E oaii 7 6 2 Software Configuration tar parate 7 6 2 1 Running the Control SOftWare cooocncnnnnccccnnnoccccnnoccncnnnoncncnnnnnnncnnnncnconnnnnnnnnnnnnn nono nnncnnnnnnncnnnnnnnnnnnns 7 6 2 2 HOW t Enter Data viiccieccscccsnccsesntnscsasnsnsesnnnsascansesneaceseteseansesngesasetasecadecedececccaed sa deceeesacecesasaceancesecnse 8 6 2 33 A A cvaseas4 edn ERa EER P NEREA Aaea naik 9 6 2 4 Moving the WINdOW ON 9 6 3 Ready to Usa A E E AA T 9 6 4 UninstallatiOn cido ladra
20. am control and can be switched using appropriate values of the control code see Section 9 7 29 9 8 GRAPHICAL DISPLAY Graphical display Min process 29 Max process 79 Min ambient 75 Max ambient 25 X samples 300 Pixel size 2 Reset Process 38 24 Ambient 22 46 Fig 34 Graphical display The upper larger display shows both the setpoint temperature green and process temperature red The lower display shows the ambient temperature Once the displayed data reaches the right hand edge of the display it starts again from the left overwriting the old data The blue vertical line indicates the current data point If the mouse hovers over either of the display areas the temperature at the mouse location either process or ambient depending on which display the mouse is over is shown next to Process or Ambient in the panel below the displays The display ranges can be set by the values in the boxes below the display Min process Max process are the minimum and maximum process temperatures shown on the upper display Min ambient Max ambient are the minimum and maximum ambient temperatures shown on the lower display X samples determines how many data points are shown on the display For slow processes the number of samples can be increased to fit on the display Pixel size adjusts the size of the displayed data points To update the display parameters
21. ble temperature profiles Gain scheduling of PID parameters 3 SAFETY Some form of isolation e g relay or optoisolator must always be used between the controller and the controlled appliance The ONLY exception to this rule is when using the controller with the 1J 7 Demonstration Module since the 1J 7 has been designed for direct connection to the controller Additional protection must be used for example a safety thermostat to protect the controlled system against overheating in the event of failure of the temperature controller As a safety measure if the controller does not receive any communication from the host computer within approximately 7 seconds e g due to a software failure it turns all of its outputs off the solid state relay output and both general purpose relay outputs This ensures that any connected equipment is automatically switched off Although the controller is immune to normal levels of electromagnetic interference such as might be experienced in a laboratory environment extremely high levels may cause unpredictable operation Reasonable measures should be taken to reduce the impact of noise on the controller The two general purpose relay outputs Section 8 2 1 are floating and can be damaged by electrostatic discharge from personnel e g by wearing woollen clothing or walking across a carpet If in doubt please ground yourself first by touching a grounded metal object before working with the front panel
22. cle time s 0 455 C PID C Manual 40 Update Fig 21 Power and cycle time control The three option buttons at the left select the power control mode If Off the output power is set to zero and the heater permanently held off If PID is selected the program performs PID calculations and sets the output power accordingly If Manual is selected the output power is set equal to the value in the blue box Power can range from 0 fully off to 100 fully on If it is only desired to record or view temperature no power control then the power control mode can be set to Off and all the other functions of the program file logging graphical display will still work as normal Cycle time This controls the cycle time used by the temperature controller for switching the solid state relay output It can be adjusted from approximately 0 5s to 60s For example if the cycle time is 1 82s and the power output level is 20 the relay output will be high on for 1 82 0 2 0 36s and low off for 1 82 0 8 1 46s The percentage on time remains constant regardless of what cycle time is selected Short cycle times are used for systems with a fast thermal response and are best suited to solid state relays because of the high switching frequency Conversely longer cycle time are used for slower systems and mechanical relays where contact wear is less of a problem To change the cycle time choose the desired time from th
23. click Reset The display will clear and start recording with the new parameters 10 CALIBRATION Calibration consists of determining two factors the ADC zero value and the ADC gain When performing calibration the thermocouple ground reference pins should be connected as shown in Fig 19 for a floating thermocouple 10 1 ADC ZERO ADC zero calibration can be performed without the need for any additional equipment Using a short piece of solid core wire approximately 0 6mm diameter short both pins on the thermocouple connector together to ensure there is zero voltage present In the software enter a reasonably large value for example 50000 into the Samples box under the ADC settings section Section 9 2 Click lt Update and wait for the value in the Zero box to clear and reappear This is the ADC zero value Set the Samples back to 1000 or whatever value was being used previously 10 2 ADC GAIN In order to determine the ADC gain a precision voltage reference must be available The exact voltage is not critical but it should be in the range 30 50mV to obtain an accurate calibration It should not exceed 70mV Connect the precision voltage reference to the thermocouple connector making sure of the polarity Again in the software enter a large value for the Samples and click the lt Update button To calculate the ADC gain subtract the ADC zero from the value shown in the Zero
24. d green when powered 8 2 FRONT PANEL See Fig 14 for a view of the instrument s front panel It consists of an 8 way pluggable terminal block for connections to the external system three status indicators and a universal thermocouple connector SSR O Thermocouple O universal RLY1O ave O Fig 14 Front panel view 8 2 1 GENERAL PURPOSE RELAY OUTPUTS Two general purpose normally open relay outputs are provided capable of switching a maximum voltage of 50V DC or AC at a maximum current of 0 2A The on resistance is typically in the range 20 100 The relay outputs are obtained from an ASSR 1228 dual solid state relay see Fig 15 and are therefore optically isolated from the rest of the circuitry For safety it is recommended that the maximum voltage at the relay outputs relative to ground be kept to below 50V 18 Optical isolation From internal circuitry To terminal block on front panel Fig 15 ASSR 1228 solid state relay internal The relay outputs can be used for example to drive an alarm as shown in Fig 16 12v External Alarm power OV supply Fig 16 Using a relay output to drive an alarm It is possible to replace the internal solid state relay should it become damaged please contact support if this is required 8 2 2 MAIN SOLID STATE RELAY OUTPUT For safe operation you must always use a relay optoisolator or other isolation element between the main SSR output
25. dicting the future temperature behaviour of the oven so for example the heater power can be decreased before the temperature rises above the 60 C setpoint This can be achieved using PID control the results of which are also shown in Fig 6 With correctly tuned PID control the temperature increases smoothly to 60 C and remains steady Note how the heater power varies over time Initially a maximum of 80 power is applied to heat the metal block quickly As the temperature begins to approach 60 C the heater power is decreased until it remains steady at around 17 If there are any temperature fluctuations the PID algorithm automatically adjusts the heater power to try and restore a steady temperature On off control PID control 70 605 507 40 Temperature C 304 20 150 200 250 0 50 100 300 0 50 100 150 300 100 100 ES 80 80 60 60 oO 40 404 e o 20 20 0 0 0 50 100 150 200 250 300 0 50 100 150 200 250 300 Time s Time s Fig 6 Comparison of on off control left hand graphs and PID control right hand graphs Setpoint stepped from 25 C to 60 C indicated by the dashed line PID parameters K 30 T 25 T 4 7 1 PID EQUATION Table 1 lists definitions of the various terms used in the PID equation Table 1 PID term definitions Term Description SV Setpoint value The required temperature PV Process value The actual current tempe
26. dows XP or Control Panel gt Programs and Features Windows Vista and 7 Because the virtual serial port is a driver it will not appear in Add Remove programs If it is necessary to uninstall the FTDI driver this can be done using the CDM Uninstaller 1 4 Windows Device Driver Uninstaller utility available from FTDI at http www ftdichip com Support Utilities htm Please refer to FTDI s documentation for details of the process 7 PID THEORY The benefits of PID control are demonstrated in Fig 6 which compares the results of using either on off or PID control to regulate the temperature of the IJ 7 module to a setpoint temperature of 60 C In the on off control scheme the heater power is maximum 100 if the temperature is below 60 C and zero 0 if the temperature is above 60 C This could be achieved by using for example a mechanical thermostat Clearly on off control does not result in a stable temperature it oscillates around the setpoint and does not settle down This is caused by the time delay between power being applied to the heater and the temperature recorded by the thermocouple starting to increase There is a similar time delay between power being removed from the heater and the temperature starting to fall As a result if the heater is turned on or off 9 when the temperature crosses the 60 C threshold the temperature will overshoot or undershoot and oscillations occur Some means is needed of pre
27. e drop down list and click Update Fig 22 The software transmits the new cycle time to the controller 22 Power control Off Cycle time s 0 455 y C PID C Manual 40 Fig 22 Setting cycle time 9 2 ADC SETTINGS See Fig 23 These control the settings of the analogue to digital converter ADC inside the controller They should not need adjustment except when first running the software or when performing calibration ADC settings Zero 16104 lt Update Gain 472 94 bits m Samples 1000 Fig 23 ADC settings Zero is the reading returned by the ADC when zero voltage is present at the thermocouple connector input A value can be entered manually or the current ADC value can be loaded by clicking the lt Update button Gain is the sensitivity of the ADC to a thermocouple voltage and is measured in bits per mV Samples controls the degree of averaging performed The controller takes this number of samples and averages them to reduce noise More samples results in lower noise but may take slightly longer to record Unless used in extremely noisy environments a value of 1000 samples is a good compromise It takes about 150s to record one sample so 1000 samples takes 0 15s The maximum number of samples is 65535 When the program is first run both Zero and Gain will be set to default values and must be changed to match the individual controller used Refer to the calibration sheet prov
28. e temperature controller and the object Remote object under measurement O Relays SSR TC SSRO Thermocouple O universal 50V 0 24 DC or AC maximum Thermocouple Remote object under measurement Ground reference Fig 20 Remote grounded thermocouple connections 21 Floating thermocouples result in better performance since no noise or ground leakage currents can flow in the sensor leads and cause an error in the voltage reading 8 2 4 STATUS INDICATORS These indicate the status of the main solid state relay output ON SSR output high and both of the general purpose relay outputs ON contacts closed 8 2 5 THERMOCOUPLE INPUT The unit can accept any type of thermocouple since the connector uses plain copper contacts and cold junction compensation is performed The maximum differential input is 30mV to 80mV Maximum absolute voltage on either terminal is 3V relative to ground Note that the choice of thermocouple is restricted by the types supported in the software currently E J K N or T The plugs on some thermocouples are sometimes very tight to insert take care not to stress the plug during insertion The plug does not have to be inserted fully just ensure that the plug terminals make contact with the socket 9 SOFTWARE REFERENCE Subsequent sections outline the use of each region of the program s interface 9 1 POWER CONTROL Power control Off Cy
29. ided with the controller and enter the Zero and Gain values specified For further details on calibration see Section 10 23 9 3 CURRENT VALUE DISPLAY Ambient Process Setpoint Power Fig 24 Current value display Ambient the temperature of the actual controller specifically the temperature of the thermocouple connector This is needed for performing cold junction compensation in order to calculate the thermocouple temperature Process current temperature of the process as measured by the thermocouple Measured in C Setpoint setpoint temperature Measured in C Power current output power range 0 to 100 9 4 THERMOCOUPLE TYPE The software can accept various types of thermocouples Some of the most common are available from the drop down list as shown in Fig 25 Thermocouple type K a e A Fig 25 Set thermocouple type 95 LOGGING The software can record time temperature and output power to a tab delimited log file Fig 26 24 m Logging Output file Browse Ic Documents and Settin Skip values 1 V Time Ambient temperature V Process temperature V Setpoint temperature V Output power Clear file Start Stor Not logging Fig 26 File logging The destination file can be selected by clicking Browse The filename entered should end with txt Data is stored in a tab separated format and can easily be im
30. ienced radio TV technician for help 5 1J 7 DEMO MODULE If the user is new to PID control they may find it helpful to purchase the IJ 7 demo module which is intended for use with the 1J 6 controller This demo module contains a small aluminium block which is heated with a power resistor The temperature of the block can be measured with the supplied bead thermocouple The module also has a buzzer which can be switched by one of the general purpose relay outputs on the 1J 6 controller These features allow the user to explore the operation of the IJ 6 controller This manual is written with operation of the IJ 7 demo module in mind to allow the user to reproduce any of the graphs shown but the underlying principles are applicable to any temperature control system 6 INSTALLATION AND CONFIGURATION Follow the steps given in these sections to install and configure the software for first use Ensure that the controller is initially disconnected from the computer and switched off Please note when installing a new version of the software manually uninstall the older version first The software has been tested on Windows XP 7 and 8 6 1 SOFTWARE INSTALLATION 6 1 1 INSTALL SERIAL PORT DRIVER The controller communicates with the host computer through a virtual COM serial port provided by FTDI http www ftdichip com A driver installation program for both 32 bit and 64 bit versions of Windows is available on the enclosed CD from the
31. mail sales eyejayinstruments com 14 REVISION HISTORY v1 3 13 12 12 Added comment re moving window v1 2 19 11 12 Added comment on safety timeout feature Corrected labels on Fig 9 v1 1 30 06 12 Re arranged software installation section v1 0 27 06 12 Initial
32. n depending on whether the thermocouple is floating or grounded The two rightmost terminals of the terminal block marked OV and are used for this purpose OV is connected to the negative supply rail of the temperature controller and hence to the negative supply of the USB port is connected directly to the negative terminal of the thermocouple connector Depending on how these terminals are connected either a floating or grounded thermocouple can be used as described below If the thermocouple is e bare e g welded bead and not attached to anything e g placed in mid air to measure air temperature e bare and attached to an object but the object itself is floating not grounded then the thermocouple is floating relative to ground and the connection shown in Fig 19 should be used A shorting link is placed between OV and thus connecting the negative terminal of the thermocouple to OV 20 Thermocouple Thermocouple SSR O universal O RLYIIO RLY2 DC or AC maximum Thermocouple Fig 19 Floating thermocouple connections If however the thermocouple is connected to an object which is grounded then the connection shown in Fig 20 should be used Here a connection is made between OV on the controller and a location near where the thermocouple junction is attached to the remote object under measurement This equalizes the grounds of both th
33. nal only mode and a setpoint temperature chosen in the example given below this is 60 C A trial value for K is then chosen It is nearly impossible to tell what a suitable value is beforehand and it is best determined by trial and error The controller is switched on and the temperature profile observed for a sufficient length of time to determine whether sustained oscillations are occurring This can sometimes be difficult to determine but 10 20 oscillation cycles are usually enough 13 If oscillations do occur K should be decreased Conversely if no oscillations or damped oscillations are observed K should be increased The controller should be switched off and the temperature allowed to fall sufficiently before performing the next test The aim is to determine the smallest value of K which produces sustained oscillations The exact value is not too critical When sustained oscillations are observed the peaks of the wave tend to top out at the setpoint temperature Fig 10 shows an example of the tuning process for three values of K demonstrating damped oscillations K 20 sustained oscillations K 27 and excessive oscillations K 50 The value of the critical gain is K 27 deg and the corresponding oscillation period is T 29s K 50 too high K 27 sustained oscillations Sag K 20 too low Calculated parameters K 27 deg T 29s Temperature C 0 50 100 150 20
34. ntering data 6 2 3 ADC CONFIGURATION The controller is provided with a calibration sheet which lists values for Zero and Gain These values are slightly different for every controller and must be entered in the software to ensure accurate operation For an explanation of these values please refer to Section 9 2 Enter the zero and gain values from the calibration sheet into the corresponding boxes in the ADC settings section of the program window as shown in Fig 5 Ignore the other boxes and buttons for the moment ADC settings Zero 16104 lt Update Gain bits mW Samples 1000 Fig 5 Entering calibration data 6 2 4 MOVING THE WINDOW If the user moves the program window by clicking and dragging on the title bar it will sometimes temporarily pause to allow the window to be moved If the window is moved for more than 7 seconds the controller itself can timeout see Section 3 as a safety feature To prevent this do not move the window for longer than 7 seconds 6 3 READY TO USE At this stage the software is ready to use If desired please refer now to Section 7 for PID Theory Section 8 for a detailed hardware reference and Section 9 for a full software reference If you have the IJ 7 demo module then you may now proceed with the experiments described in its manual 6 4 UNINSTALLATION The temperature control software can be uninstalled as normal through Control Panel gt Add Remove Programs Win
35. nual setpoint 30 Load test program txt program Start Stop Hold Running Segment 1 Fig 30 Setpoint amp program control shown with a program running The setpoint temperature can either be set manually or can be varied according to a user defined program If there is no program running then the software automatically uses the setpoint value in the Manual setpoint box A sample temperature profile is shown in Fig 31 and the associated program in Fig 32 e Program Segment 3 Actual RLY2 on hold 3 Temperature C Segment 1 Qa o 3 E o N gt x Natural cooling 0 5 10 15 20 25 30 35 40 Time minutes Fig 31 Example temperature program showing both the programmed setpoint value and the actual temperature reached 27 P 1J 7 Example Program txt Notepad File Edit Format View Help IJ 7 Example Program 1 40 10 0 Fig 32 Program to produce profile shown in Fig 31 The first line can contain any text for the user s reference title date etc It must not be blank however Each segment of the temperature profile is defined by a line in the file Each line contains four numbers separated by commas as defined below Segment number start temperature segment duration control code Segment number Indicates which segment the line refers to Start temperature The temperature in C at which the segment starts The temperature is ramped up
36. of the temperature controller and the external system and not connect the main SSR output of the temperature controller directly for example to a MOSFET or transistor switch The only exception is the 1J 7 demonstration module which can be connected directly This provides a variable duty cycle output suitable for driving a relay or optoisolator The output voltage is around 11V open circuit dropping to 10V when delivering the maximum output current of 40mA as shown in Fig 17 Output resistance is around 300 The cycle time can be adjusted from approximately 0 5s to 60s via the software Longer cycle times should be used for systems which respond slowly to changes in heater power If a mechanical relay instead of a solid state relay is used instead long cycle times help to prolong the contact life since the switching frequency is reduced 19 11 2 11 07 10 8 a o D 1 10 44 Voltage V 10 2 4 10 0 9 8 T T T T 0 10 20 30 40 50 Currrent mA Fig 17 SSR output voltage and current Fig 18 shows an example of connecting the temperature controller to a brick type solid state relay A reed relay or optoisolator can also be connected instead providing the current draw is kept below the maximum of 40mA To from switched load Fig 18 Connections for external solid state relay 8 2 3 THERMOCOUPLE GROUND REFERENCE A suitable thermocouple ground reference must be chose
37. own the temperature rise The derivative term can be used to correct overshoot or oscillations caused by the integral term as shown in Fig 9 Because this allows the use of a smaller value of T addition of the integral term can result in a faster system response However because the derivative term is based on the process temperature it can be sensitive to noise and should not be used in noisy environments 70 65 60 55 Temperature C 50 45 r r T T r 0 50 100 150 200 250 Time s Fig 9 Proportional integral derivative control Addition of the derivative term removes the oscillations Setpoint stepped from 20 C to 60 C indicated by the dashed line 7 2 TUNING As can be seen from the above examples PID control only works when the parameters Kp Tj Ty are chosen correctly This process is called tuning and can be performed manually Tuning is best performed at or near the temperature of interest since the parameters can themselves depend on temperature It was mentioned above that if K is too large oscillations can occur The smallest value of K which causes sustained temperature oscillations in a proportional only control system is called the critical gain K and the period of the oscillations is T Once K and T have been determined using either of the methods below suitable values for the parameters K Tj Ta can be calculated from them 7 2 1 CLOSED LOOP The controller is placed in proportio
38. ported into programs such as Microsoft Excel or Microcal Origin for processing The user can choose which values to record to the file by ticking the appropriate boxes An example of a log file after being imported into Excel is shown in Fig 27 If a file already contains log information the new log is appended to the end as shown 1 Logging started at 08 05 2012 21 05 06 2 Time Ambient Process Setpoint Power 3 0 20 09375 2572 347 30 0 4 0 972 20 0625 2572 174 30 0 5 1 94 20 0625 2572 065 30 0 6 2 873 20 09375 2572 13 30 0 7 3 818 20 0625 2572 065 30 0 8 4 749 20 09375 2572 238 30 0 9 5 767 20 0625 2572 174 30 0 10 Logging stopped at 08 05 2012 21 05 13 11 Logging started at 06 05 2012 21 05 17 12 Time Ambient Process Setpoint Power 13 0 20 0625 2572 174 30 0 14 1 20 0625 2572 282 30 0 15 1 937 20 09375 2572 347 30 0 16 2 944 20 0625 2572 282 30 0 17 Logging stopped at 08 05 2012 21 05 21 Fig 27 Example of log file The time in the log file is the time elapsed in seconds since logging was started Note that it often does not increase in uniform increments This is because each cycle of the program may take a slightly different time to run depending on the resource usage of the computer If other programs are also running or CPU usage is high this may increase the interval between log entries slightly but will not affect the temperature control see Section 11 3 By default a log entry is recorded every
39. rature of the process e Error Difference between the setpoint and process values e SV PV When SV gt PV the error is positive P Output power This is the power applied to the heating element P lies within the range 0 fully off to 100 fully on Kp Proportional gain Units power per degree C T Integral time Units seconds Ta Derivative time Units seconds 10 Ko Ti Ta are the three PID parameters which determine how the PID control loop responds to changes in the setpoint and process temperatures The PID control equation shown below is used to calculate the power which should be applied to the heating element It consists of three terms corresponding to the proportional integral and derivative actions P K B fed Kr 1 K e edt da PO Tido P dt If the power P calculated from this equation is outside the valid limits of 0 to 100 it is clipped to whichever limit is relevant Note that although the above form of the PID equation is the most common other sources sometimes use a different form or alternative symbols for the various terms However the notation used here is self consistent and matches that used in the accompanying software The contribution of each of the three terms is explained and demonstrated below 7 1 1 PROPORTIONAL P CONTROL If only proportional action is used the control equation becomes P Kye The applied power depends only on the e
40. rror between the setpoint and process temperatures Fig 7 shows an example of proportional control with different values of K As K is increased the steady state temperature reached moves closer to the setpoint but the temperature also becomes more unstable Although for example K 3 results in a smooth increase to a stable temperature of around 55 C K 10 results in an initial overshoot before the temperature settles to around 57 C In fact if K is too large oscillations can become permanent and the temperature never reaches a steady value Very large values of K for example greater than 1000 simulate on off control since the power changes rapidly from 0 to 100 as the temperature crosses the setpoint Temperature C Time s Fig 7 Proportional only control for four different values of K Setpoint stepped from 20 C to 60 C indicated by the dashed line 11 With proportional only control the steady state temperature reached is always a certain amount called the droop below the setpoint temperature which is clearly undesirable This can be solved by the addition of the integral term Pz PROPORTIONAL INTEGRAL PI CONTROL With proportional and integral action the equation becomes Kp t P K e edt T i Jo By integrating the error over time the integral term gradually compensates for the droop caused by the proportional term It attempts to eliminate the droop within a time roughly equal to T Smaller
41. terminal block IJ Instruments Ltd accepts no responsibility for loss or damage to property caused by careless or incorrect usage of this device 4 FCC NOTICE This device complies with part 15 of the FCC Rules Operation is subject to the following two conditions 1 This device may not cause harmful interference and 2 this device must accept any interference received including interference that may cause undesired operation This equipment has been tested and found to comply with the limits for a Class B digital device pursuant to part 15 of the FCC Rules These limits are designed to provide reasonable protection against harmful interference in a residential installation This equipment generates uses and can radiate radio frequency energy and if not installed and used in accordance with the instructions may cause harmful interference to radio communications However there is no guarantee that interference will not occur in a particular installation If this equipment does cause harmful interference to radio or television reception which can be determined by turning the equipment off and on the user is encouraged to try to correct the interference by one or more of the following measures Reorient or relocate the receiving antenna Increase the separation between the equipment and receiver Connect the equipment into an outlet on a circuit different from that to which the receiver is connected Consult the dealer or an exper
42. time the program completes a cycle roughly every second For slowly varying processes this can lead to a large amount of recorded data To prevent this the log file can skip values as specified in the Skip values box For example if 3 is entered the log file only records once in every three program cycles 25 Clear file allows the user to erase the current log file Start and Stop control the log file operation The current status Logging Not Logging is displayed beneath the buttons 9 6 PID PARAMETERS AND GAIN SCHEDULING PID parameters Use GS factors Kp 4 IV 4 Ti 45 4 W 2 Td 227 Vv Enable gain scheduling Load file 1J Gain Schedule txt Reset integral Fig 28 PID parameters and gain scheduling Here the user can set values for the proportional gain K integral time 7 and derivative time Tq The check boxes under Use determine which of the terms in the PID equation proportional integral or derivative the program uses For example if only the top check box is ticked the program functions as a proportional only controller and ignores the values of T and Ty It is possible to perform gain scheduling see Section 7 2 3 where the PID parameters are changed depending on the current process temperature To enable gain scheduling first create a text file using any text editor such as Notepad which contains the gain scheduling information An example of
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