Vue-TEC Operators Manual Rev. 1.1
Table of Contents Product Description...3 Typical Application Diagram...3 Specifications...4 Front Panel Connectors...5 Rear Panel Connectors...6 WinVue Windows User Interface Software Installation Procedure...8 Vue-TEC Tutorial...8 Step #1. Necessary Connections...8 Step #2. Start up WinVue and the Main TEC Control Window...9 Step #3. Thermistor Coefficient Calculation...9 Step #4. Specifying the Temperature Lock Window...11 Step #5. Setting TEC Driver Output Limits...12 Steps 6-9. Temperature Servo Tuning Wizard...13 Step #6a. Manual TEC Control...14 Step #7a. Thermal Load Characterization...14 Step #8a. Temperature Servo Simulation...16 Step #9a. Automated Control of the TEC...17 Steps 6-9: The Temperature Servo Tuning Window...18 Individual Window Descriptions...18 Main TEC Control Window...18 TEC Utility Window...20 Temperature Log Window...22 Temperature Servo Simulation Window...22 Measure Thermal Load Window...23 Thermistor Coefficient Window...26 Data Log Window...27 Service Window...27 Communications Log Window...27 Utility Window...27 Connection Settings Window...28 Programming and Customization Information...28 Communicating with the Vuemetrix TEC Driver...28 Fault Codes...29 RS232 Pass Through Feature...31 Revision History...32
Product Description The Vue-TEC delivers up to 10A of low noise drive current for a Peltier device (thermoelectric cooler or TEC) with voltages up to 21.5V. The driver is operated by a microprocessor that actively regulates the temperature of a thermal load and provides extensive start-up and diagnostic algorithms. The Vue-TEC has a special passthrough feature that allows specially formatted commands to be relayed onto another device attached to its secondary RS-232 port. This allows you to control the TEC driver plus the second device from a single host serial port. For convenient mouse-driven setup and adjustment, the Vue-TEC Developer's Kit includes a Windows application, WinVue. For customers who prefer to develop their own interface software, the VueMetrix web site www.vuemetrix.com contains a complete list of serial commands, USB drivers and associated documentation. Typical Application Diagram User Safety DO NOT OPEN AND ATTEMPT TO SERVICE THE UNIT. There are no user serviceable parts inside the Vue-TEC. Only qualified service personnel should remove the cover.
Specifications Input and Output Input Voltage TEC Output Voltage Range 15V ~ 24V DC 0V up to ±90% of input voltage at 10A output TEC Output Current Range 0 ~ 10A TEC Output Voltage Resolution (Typical) 33mV for 24V input 21mV for 15V input TEC Output Voltage Ripple (Peak to Peak) < 6% (when output current > 2A) Fan Driver Fan output voltage 12V Fan output maximum current 1.5A Temperature Sensing Temperature Sensor NTC 10 kohm (not included) Temperature Resolution 0.01 o C typical Temperature Stability 125 ppm/ o C Temperature Accuracy user calibrated General Power Supply Efficiency (Typical) 90% (for output > 30W) Dimensions 7.5 x 2.7 x 1 Connectors Thermistor Input 2 pin Molex Microfit PN: 43045-0200 Data/Control 3 pin RS-232 (Molex 70553-0002) or USB TEC and Fan Output 8 pin Molex Mini-Fit Jr. (PN: 39-30-1080)
Front Panel Connectors (The view is looking into the TEC driver. Pin numbers may also be on the mating connector housing.) Temperature Sensor Connector Pin 1 Thermistor Minus Pin 2 Thermistor Plus Connector Type Molex Microfit PN: 43045-0200 Mating Connector Housing Molex 43025-0200 Mating Terminal / Wire Molex 43030-0009 (or compatible) / 24AWG wire TEC Output Connector Pin 1 Fan return Pin 2 TEC Output Minus 1 Pin 3 TEC Output Plus 1 Pin 4 TEC Output Plus 1 Pin 5 Fan positive (+12V) Pin 6 TEC Output Plus 1 Pin 7 TEC Output Minus 1 Pin 8 TEC Output Minus 1 Connector Type Molex Mini-Fit Jr. 39-30-1080 Mating Connector Housing Molex 39-01-2080 Mating Terminal / Wire Molex 44476-1111 (or compatible) / 18 AWG wire 1 The TEC connection polarity should be such that a positive voltage causes the temperature to rise.
Rear Panel Connectors (The view is looking into the TEC driver. Pin numbers may also be on the mating connector housing.) Power Input Connector Pin 1 Input Minus Pin 2 Input Plus Pin 3 Input Minus Pin 4 Input Plus Connector Type Molex Mini-Fit Jr. 39-30-1040 Mating Connector Housing Molex 39-01-2040 Mating Terminal / Wire Molex 44476-1111 1 (or compatible) / 18 AWG wire 1 The recommended mating terminals for the power input and output are Molex 44476-1111 and -1112. These are high current versions in the Molex terminal family. Lower current versions such as Molex 39-00-0039 can be used if the current per pin will always be < 3A. RS232 Output Connector Pin 1 Ground Pin 2 RS232 Transmit (TEC Driver to another RS232 device) Pin 3 RS232 Receive (another RS232 device to TEC Driver) Connector Type Molex C-Grid SL PN: 70553-0002 Mating Connector Housing Molex 50-57-9403 Mating Terminal / Wire Molex 16-02-0096 / 24 AWG wire RS232 Input Connector Pin 1 Ground Pin 2 RS232 Receive (PC to TEC Driver) Pin 3 RS232 Transmit (TEC Driver to PC) Connector Type Molex C-Grid SL PN: 70553-0002 Mating Connector Housing Molex 50-57-9403 Mating Terminal / Wire Molex 16-02-0096 / 24 AWG wire Note: The Vuemetrix PN 1000-0229 is a cable that converts from the RS232 input / output connector to a standard 9 pin female RS232 connector. USB Connector
Connector Type Standard USB B connector
WinVue Windows User Interface Software Installation Procedure The WinVue program and this operators manual are located on the CD-ROM included with the TEC Driver. Step 1: Copy folders to PC Copy the contents of the CD-ROM to your computer s hard drive. Do not change the folder and subfolder structure and do not open the.zip file. Step 2: Launch the program Locate the tec.exe file and double click to launch the program. Upon startup, WinVue will scan the serial ports and USB ports of the PC to try to connect to any Vue-TEC that it finds. If none is found, the message No connection will appear near the upper left of the main window. If one is found, the white activity banner in the upper left of the main window will display the connection status. If more than one is found, all will be listed in the Connection menu. The active connection will be designated by a check mark in the menu, and will be named in the activity banner in the upper left of the main window. To switch connections select the one you want from the Connection menu. Vue-TEC Tutorial Step #1. Necessary Connections Be sure the following items are connected to the TEC driver: Input power (+15V to +24V) TEC and fan Thermistor USB or RS-232 input from a computer Hint: The TEC driver fan output is always on, so once the fan is plugged into the TEC driver you should hear the fan running.
Step #2. Start up WinVue and the Main TEC Control Window Start WinVue by running the file tec.exe in the folder that contains the WinVue software. Assuming that the PC is connected to either the TEC driver USB port or the RS-232 IN port, WinVue will automatically detect the TEC driver. WinVue starts up with the Main TEC Control window open. This window reports the TEC s output voltage and current. Initially the temperature measured should be approximately the ambient temperature. The TEC driver is initially programmed for a particular 10kOhm NTC thermistor see the next section for details. Step #3. Thermistor Coefficient Calculation A 10kOhm NTC thermistor is so called because it has a resistance of 10kOhm at 25ºC. The dependence of this resistance on temperature will vary significantly across devices. VueMetrix has selected a particular thermistor as our standard, RL0503-5820-97-MS from Thermometrics. The Vue-TEC firmware has a set of default coefficients for it. If you prefer to use another model of thermistor, the temperature reported by the Vue-TEC will be in error unless the procedure in this section is performed. In the Vue-TEC the thermistor forms a simple voltage divider with a fixed 10kOhm resistor and a 3V source. The divided voltage is read by the microcontroller to compute the current temperature as follows: Let V = the voltage across the thermistor being sensed by the microcontroller Temperature = A + BV + CV 2 + DV 3 The thermistor coefficients (A, B, C, and D) are stored in the TEC driver, not in WinVue. WinVue has a tool for calculating the ABCD coefficients. Go to View menu and select Thermistor coefficients to open the Thermistor coefficients calculation window. WinVue will by default assume the 3V bias and the 10kOhm bias resistor.
Depending on the data provided the thermistor manufacturer, there are several options for generating the necessary temperature versus resistance data. The most flexible option is to generate a comma delimited file of temperature versus resistance. It would look like: -30,180100-25,132400-20,98320-15,73720 and so on where first column is the temperature, and the second column is the resistance. Hint: spreadsheet programs like Excel can save in the comma separated value format (.csv). Hint: limit the range of temperature to the range of interest in the application. This will optimize the accuracy of the curve fitting. At least one thermistor manufacturer also uses the terms ABCD in a formula that describes the change in resistance as a function of temperature. Do not confuse this with the same terms used to describe the conversion of voltage to temperature by the VueMetrix controller. Click on the Load button to load the,csv file into WinVue. The software will then calculate the ABCD coefficients. Click on the Upload button to transfer these coefficients to the TEC driver. Step #4. Specifying the Temperature Lock Window A large number of factors influence how close the Vue-TEC can regulate the load to a temperature set point. Theoretically the controller is capable of sensing the temperature with an precision of approximately 0.001ºC. This will vary owing to the nonlinear nature of the thermistor resistance function and the amount of electrical noise in the circuit. The inherent stability of the environment also plays an import role in limiting the controller's ability to regulate. To account for this variability the controller allows some latitude in defining what constitutes its so-called lock condition (i.e., the temperature is stable and under servo control). Numerically this is termed the lock window, the permissible deviation from the set point in the locked state. It defaults to 0.02ºC. If this window is too small it will result in a fault when the controller is unable to achieve lock. If it is too large the controller will enter the lock state when the temperature is not yet stable. This will affect other devices if the passthrough feature is in use. The controller will always attempt to achieve the set point as closely as possible.
Go to the TEC Utility window. To have the lock window be ±0.05 o C, type 0.05 into the Servo lock window text field and hit Enter. The number typed here is actually the allowed deviation from the set point. Step #5. Setting TEC Driver Output Limits The Vue-TEC s output voltage range is up to 95% of the input DC voltage. So if the input is 15V, the output can be up to 15 * 0.95 = 14.25V. This may be too high for your TEC. You can set an output limit to prevent the controller from over-driving the TEC. To calculate the drive limits use the following formula: P heating = V max / (V in * 0.95) * 50.0 + 50.0 P cooling = 50.0 - V min / (V in * 0.95) * 50.0 where: V in is the input DC voltage P heating is the maximum drive for heating P cooling is the minimum drive for cooling V max is the maximum plus voltage for your TEC V min is the maximum minus voltage for your TEC If P heating is > 100.0 use 100.0. If P cooling is < 0.0 use 0.0.
In the TEC Utility window type P heating into the Maximum drive % and text field and press enter. Type P cooling into the Minimum drive % text field and press enter. Steps 6-9. Temperature Servo Tuning Wizard The recommended method of performing steps 6-9 is to use the Temperature Servo Tuning window or wizard, which will systematically walk through these steps. The next four sections describe a method that is more complicated to use, but results in a more extensive characterization of your system.
Step #6a. Manual TEC Control The TEC Utility window has a slider near the bottom of the window that allows the user to control the drive to the TEC. Use caution! In this condition the Vue-TEC is not controlling the temperature of the load. 50% is the neutral position. There is no drive, and the TEC driver output voltage and current are both zero. Go to 51% drive and see that the TEC driver voltage and current will both go positive. TEC Connection Polarity for this Product: When the drive is ABOVE 50%, the TEC output current is POSITIVE, and the temperature sensed should be RISING. The above convention must be implemented for the TEC servo to work. So if the drive is above 50%, and the temperature is falling instead of rising, this means that the TEC connections need to be reversed. Step #7a. Thermal Load Characterization The goal of this step is to discover a system model for the thermal load. For best results put the system into a state that closely approximates the operational conditions. For example, sources of heat should be about the same as when the system is fully functional. Wait until the temperature is relatively stable, say a rate of change less than 0.1ºC per minute. In the Load characterization window the thermal load will be subjected to alternating cycles of heating and cooling.
TEC max % - This is the high value of the drive during the measurement cycle. Make sure it is a drive level that your system can withstand without damage. TEC min % - This is the low value of the drive during the measurement cycle. Make sure it is a drive level that your system can withstand without damage. Period This is the length of a single heating and cooling cycle. In this example it is 160 seconds, which means 80 seconds of heating and 80 seconds of cooling. The period needs to be long enough so that the resulting temperature change should have a curvature in it. In the example the TEC drive will step from 18% to 21%. During each half-cycle the load temperature will approach toward final value exponentially. The period should be long enough that the temperature change begins to decrease. After the proper max %, min %, and period values are entered, hit the Start button to start data acquisition. The process continues until you hit the Stop button. Two periods are generally sufficient.
The graph shows the temperature change with respect to time. The program is now ready to perform a least-squares optimization process that will result in an empirical model for the thermal load. Hit the optimize model button. There will be a brief delay as the model is determined by iteration. At the end a curve representing the model results should closely approximate the data. It is a good practice to save the raw data to a.csv file using the Save button, and to make a note of the four model parameters. For a theoretical description of the modeling process refer to the Applications note http://www.vuemetrix.com/support/tech/tempcontrolmeas.html#servtheory, sections 2.6 and 2.7. Hit the Transfer coeffs to model window button. This will transfer the model parameters to the Temperature servo simulation window in preparation for the following step. Step #8a. Temperature Servo Simulation The Temperature servo simulation window is arrived at from the Load characterization window at the end of step #7. It can also be opened from the pull-down menu and the load model coefficients can be entered by hand. The Vue-TEC temperature servo uses two control coefficients: the slope gain and the offset gain. These are somewhat analogous to the differential and proportional terms in a traditional PID control algorithm. This window uses the load parameters from the previous step and a simulation of the servo algorithm to predict the system's performance, allowing quick adjustment of the coefficients for best results. The set point (C) and Initial temperature (C) boxes specify the starting temperature and the target temperature of the simulation. Start with a slope gain of 1 and and a offset gain of 1. Hit the Run button to see the temperature response. The window can optimize your initial choices, so the choices here are not critical. Increase the offset gain and you will see that the white line (temperature) will approach its target faster. As usual with control problems,
faster approaches lead to overshoots. The slope gain is the damping factor in this control algorithm. One approach is to keep adding offset gain till we have some overshoot in the temperature response. Then increase the slope gain till the overshoots go away. When the performance looks reasonable hit the Fit button and WinVue will perform a further optimization. Note these results for future reference. Step #9a. Automated Control of the TEC The slope gain and offset gain determined in step #8a need to be entered into the TEC driver. This is done in the TEC Utility window. Once transmitted to the TEC driver, they will be stored in non-volatile memory for future use. To have the TEC regulate the heat load, go to the Main TEC Control window, and press the Enable servo button. That window has a slider for setting the target temperature. You can right-click on the Set temperature slider to type in an exact value. To keep track of the temperature change versus time, go to View menu and select the Temperature Log window. Press the Start button to start taking data. The TEC driver has an auto-start feature in the Main TEC Control window. Every time the user selects a new temperature via the slider, the selected temperature is stored in the TEC driver flash memory. If the TEC driver loses input power and is turned back on, the most recent user selection will appear in the WinVue slider. However by default the TEC driver will not engage the servo at power on.
To have the TEC driver always engage the servo, check the Autostart box in the lower right hand corner of the Main TEC Control window. Once Autostart is turned on, the servo will always be engaged and manual control is lost. For example, if Autostart is turned on, the user cannot disengage the servo by clicking on the Enable servo button in WinVue. To have that button work again, uncheck Autostart. Further information and details regarding the temperature measurement and control scheme can be found online at: http://www.vuemetrix.com/support/tech/tempcontrolmeas.html. Steps 6-9: The Temperature Servo Tuning Window An easier way to perform steps 6-9 is to use the Temperature Servo Tuning Wizard. This will walk through the same process documented above, but with a higher level of automation. After the final step the wizard will upload the servo constants to the controller, and it will be ready for operation. Each step in the wizard has a help screen that provides further information. Individual Window Descriptions Main TEC Control Window This window provides primary control functions for routine operation of the TEC. Serial Number The serial number of the TEC driver appears in the title bar. Enable Servo Click this button to enable or disable the TEC servo loop. When enabled, the driver attempts to achieve the temperature
set by the user. When disabled, the driver goes to zero output on both the TEC positive and TEC negative terminals. Servo State: Off The servo is off and the TEC drive circuitry is disabled. Servo State: Seeking The servo is attempting to capture the set point but has not yet succeeded. Servo State: Locked The servo has captured the set point and held it successfully for more than ten seconds. Servo State: Manual The servo is off and the TEC is under control of the Drive slider in the TEC Utilities window. Servo State: Fault Upper rail (fault) The TEC drive has been at the upper rail (100%) for too long, and the temperature is not increasing. Lower rail (fault) The TEC drive has been at the lower rail (0%) for too long, and the temperature is not decreasing. Lost lock (fault) The servo was previously locked but has lost the set point and is unable to reacquire it. No convergence (fault) The servo was unable to acquire lock. ADC limit (fault) The microprocessor sees a thermistor voltage value that is too high, indicating a bad connection to the thermistor. TEC driver (fault) The circuit that drives the TEC reported a hardware fault. Set Temperature (C) Slider This slider sets the target temperature for the TEC servo. Right click on the slider to enter a precise value. The slider value can be changed at any time, and the TEC driver stores the latest value in non-volatile memory. Error (C) Bar Graph This shows the difference between the user set point and the actual temperature. Measured Temperature The current temperature from the thermistor. Drive % The current TEC driver output level, with 50% being the neutral value (no output). At 100%, the TEC output plus terminal is as high as it can be, which is between 90% to 95% of the input voltage. The exact voltage output depends on the amount of current being pumped out. At the same 100%, the TEC output minus terminal is as low as it can be, which is around 0V. Conversely, at 0%, the TEC output plus terminal is around 0V while the output minus terminal is as high as it can be. System Hours The total number of hours this TEC driver has been running. TEC Current This is the output current leaving the TEC plus terminal. The standard used in this software is that when drive is above 50%, the output current should be POSITIVE, and the
TEC should be heating up the load. When drive is below 50%, the output current should be NEGATIVE, and the TEC should be cooling the load. TEC Voltage The TEC driver output voltage. This value is always positive, whether the drive is above or below 50%. The polarity of the out current is indicated by the TEC current reading. Autostart When this box is unchecked, the TEC driver will power up with the servo in the off state. Checking this box will engage the servo automatically at power on. TEC Utility Window This window is used for initial setup of the temperature servos. The user can manually control the TEC driver, and can enter parameters that govern how the TEC driver works. See the TEC Driver Tutorial section for more detail. Slope gain This control parameter is the damping factor. Larger slope gain tends to damp the TEC driver s approach to the final temperature set point, but too large a slope gain can create oscillations. Offset gain This is the proportional gain control parameter. Larger offset gain makes the TEC driver approach the final set point faster, but at the cost of overshooting. Thermistor Coefficients A, B, C, D The microcontroller senses the voltage across the thermistor. These microcontroller converts that voltage into a temperature value according to the equation: T = A + BV + CV 2 + DV 3. Enable drive setting When this box is unchecked, the TEC driver output is under the control of the TEC servo. Checking this allows manual control of the TEC driver output via the Set drive % slider. If this box is checked by the user and WinVue immediately fights back and unchecks it, that means the autostart feature is enabled. In other words, the autostart checkbox in the Main TEC Control window overrides the Enable drive setting checkbox. WARNING: WHEN OPERATING THE TEC IN MANUAL MODE THE TEMPERATURE IS NOT REGULATED. IT IS IMPORTANT TO USE EXTRA CAUTION NOT TO DAMAGE THE THERMAL LOAD. Set drive % When the enable drive setting box is checked, the user can set the TEC output via this slider. The full range of available TEC drive is mapped to a scale from 0% to 100%.
The 100% is maximum heating, 0% is maximum cooling, and 50% is neither heating nor cooling. When the servo loop is enabled, this slider moves back and forth as the drive signal changes under servo control. Temp change rate This shows the temperature rate of change. In order for the TEC driver servo to be considered locked, this rate of change has to be close to zero. Servo lock window o C This determines how much deviation is allowed between the temperature set point and the actual temperature for a lock to occur. For example, if the servo lock window is 0.020 degrees, and the user wants a set point of 20 degrees, regulating the temperature to between 19.98 to 20.02 degree counts as lock. As soon as the temperature falls out of this range, the servo status will change from locked to seeking. Maximum drive % The maximum percentage drive limit is used to protect the TEC from being subjected to over-voltage. As a calculation example, assume the input is 24V. The driver output is at most 95% of input = 24 * 0.95 = 22.8V. This 22.8V corresponds to 100% drive, while 50% corresponds to 0V output. Suppose a certain TEC can only take a maximum voltage of 12V, the maximum percent drive should be 50% + 12/22.8 * 50% = 76.3%. Minimum drive % The minimum percentage drive limit is used to protect the TEC from being subjected to over-voltage when current is flowing in the reverse direction. Extending the example in the Maximum drive % section, the minimum drive percentage would be 50% - 12/22.8 * 50% = 23.7%
Temperature Log Window This window records the temperature relative to time and plots it on a graph, along with the percentage of drive applied. This graph can be used to determine the performance of the servo such as the time required to move from one temperature to another. Start Start recording data. Stop Stop recording data. Clear Clears the graph. Export data to file Exports the time, temperature, and percentage drive data to a comma separated value (.csv) file. Export data to clipboard Puts the data onto the Windows clipboard in a tab-delimited format. Temperature Servo Simulation Window This window is a tool to help optimize the control coefficients: slope gain and offset gain. It is described in greater detail in the Tutorial section.
The first four parameters are coefficients for the system model. These come from the Measure Thermal Load window. Their meanings are briefly described in the documentation for that window. The next two coefficients are control coefficients for the TEC servo loop: Slope Gain The damping factor for the TEC control. A larger slope gain will slow down the approach to the target temperature and prevent overshoots. However, a slope gain that is too large will cause oscillations. Offset Gain The proportional gain factor for the TEC control. A larger offset gain makes the temperature approach its target value faster, but at the cost of overshooting. The remaining controls are about running the load regulation simulation. Update Interval (s) This value should be 0.1 for this product (Vue-TEC). Set point (C) The target temperature for the simulation. Initial Temperature (C) The starting temperature for the simulation. Get coefficients from TEC #1 Obtain slope gain and offset gain values from the TEC driver that is currently connected. Run Run the calculation once. The white line stands for temperature and will move from the initial temperature to the set point temperature according to the servo gain constants. Fit WinVue will optimize the slope gain and offset gain coefficients. Time to lock (s) The time it takes to go from the initial temperature to the set point temperature. Measure Thermal Load Window With this window, the user can subject the load to alternating cycles of heating and cooling. By analyzing the temperature response due to these heating and cooling cycles, a system model can be created. Go through the tutorial to see the role that it plays in using this product.
The first few parameters describe the heating / cooling cycle applied to the load: Square wave Apply a square wave as the load excitation method. Most of the time, use this option as opposed to the sine wave option. Sine wave Apply a sine wave as the load excitation. Period The period of the square wave or sine wave. TEC max % The percent drive for the heating portion of the load excitation. TEC min % The percent drive for the cooling portion of the load excitation. The next few buttons control the characterization process: Start Start the heating / cooling cycle. Stop Stop the heating / cooling cycle. Usually two periods of the excitation are sufficient. Save Save the data points obtained during the characterization process. Recall Recall data points obtained from a previous characterization process. The four coefficients underneath Model Load are derived by the computer after an analysis. They model the thermal load being driven by the TEC driver. T(C) at 50% drive The thermistor steady state temperature if the TEC is neither heating nor cooling. T change per % drive The steady state temperature change for every 1% drive applied to the TEC. Time constant (s) If the TEC drive undergoes a step change, say from 21% drive to 20% drive, the thermistor temperature will start at temperature X and exponentially decay
to temperature Y. The time constant measures how fast this exponential decay happens. The larger the thermal mass, the longer it will take. Delay (s) The time it takes for a step change in the TEC driver output signal to register as a change in the thermistor temperature. The next few buttons runs computer analysis on the data obtained during the characterization process. Run model once The computer will graph a curve based on the four previously mentioned coefficients that are listed under Model Load. If these coefficients are a good fit the blue curve will appear close to the white curve. Optimize model The computer will vary the four coefficients listed under Model Load so that the blue curve will match the white curve as closely as possible. This step can take a few minutes and the result is a set of four coefficients to model the thermal load driven by the TEC driver. Stop This stops the fitting process. Chi sqr of fit This value measures how close the computer model curve (blue) actually fits the system response curve (white). A smaller value means a better fit. Transfer coeffs to model window Transfers the four coefficients listed under Model Load to the Temperature Servo Simulation window.
Thermistor Coefficient Window The TEC driver detects the voltage (V) across the thermistor and translates that into a temperature (T) value based on the formula: T = A + BV + CV 2 +DV 3 The thermistor coefficient calculation window is a tool to figure out the ABCD coefficients. The top four buttons represent four different ways to describe a thermistor. R stands for the thermistor resistance and T stands for temperature. ABCD Model Some thermistor manufacturers use a model where R = 10000 * exp(a + B/T + C/T 2 + D/T 3 ). The values for ABCD are given in the datasheet. WinVue will use these to compute a curve of temperature versus voltage. Please note that these ABCD coefficients for R(T) are NOT the same as the ABCD values use by the controller to compute T(V). Beta Model The user provides a beta value where the thermistor is characterized by R = 10000β(exp(1/T)). Steinhart-Hart Model The user provides ABC values where the thermistor is characterized by 1/T = A + B*ln(R) + C*(ln(R)) 3 Load Loads a comma delimited file where the first column is the temperature and the second column is the resistance. Using this method, the user can model just the range of temperatures that will actually be encountered to achieve the best accuracy in that range. Example: -30,180100-25,132400-20,98320-15,73720 etc Upload Uploads the ABCD coefficients shown in this window to the TEC driver where they will be stored for future use. You can see what the TEC driver s current ABCD values are by looking at the TEC Utility window. Ballast (fixed) resistor (ohms) For all standard Vue-TECs, this box should say 10000 (10kOhm). Reference Voltage For all standard Vue-TECs this box should say 3.0.
Data Log Window This window records various system data into a comma delimited file. Start Starts the data recording process Pause Pause the data recording process Stop Stops the data recording process Data Interval The length of time to pause in between data recordings. Service Window This window displays a number of parameters that are intended for debugging uses only. It may be referred to during tech support sessions. Communications Log Window This window has a single Enable Logging button that shows the communications between WinVue and the TEC Driver. It is intended for use during tech support sessions only. Utility Window This window is intended for firmware upgrade and for programmers who will be writing specialized software to command the TEC driver. Firmware version The official firmware for standard products starts at 1. If the version is greater than 1000, then it s a custom or trial firmware. System serial number Serial number of the TEC driver Type a command and Reply from controller For example, the sn? command returns the current serial number, which is 12. List commands lists all of the commands implemented on the TEC driver. For a fuller explanation of each command, see the web site. The list in WinVue is always the most up-to-date. Run macro You can store a list of commands, like sn?, in a text file, and run them using the Run macro button.
Upgrade firmware Use this to load a different version of the driver firmware. Connection Settings Window All previously mentioned windows are accessed via the View menu. The Connection Settings window is accessed via the Connection menu. Disconnect Close the port currently being used by WinVue. This allows another program to use the serial port. Reset USB devices Rescan the USB bus looking for a TEC driver. This button is used when a TEC driver is attached after WinVue has started. Reset serial devices Rescan the COM ports looking for a TEC driver. Programming and Customization Information Communicating with the Vuemetrix TEC Driver RS232 Communication The RS232 connector uses just three lines: ground, transmit, and receive. There is no flow control or hardware handshake. To open a COM port to the TEC driver, use the following RS232 settings: Baud rate = 115200 Parity = None Data bits = 8 Stop bit = 1 All communications are in ASCII text. Each command to the controller should be terminated by either a > character, a carriage return or a new line (hex character values 0D and 0A).
All responses are in ASCII text as well. So if the computer asks for the serial number sn?>, and if the serial number is 12, the response will be a character 1 and a character 2. The response will not be a single byte that represents the numeric 12. USB Communication A DLL file is available to simplify the task of communicating with Vue-TEC via the USB. Details are in the support website at http://www.vuemetrix.com/support/. Command List The full list of commands supported by the TEC driver, go the Utility Window and click on the List Commands button. These commands can be tried out in the utility window s Type a command textbox. Further Information For a detail description of the commands and communicating to Vumetrix products, visit the support website at http://www.vuemetrix.com/support/, scroll down to the section that says Programmer s documentation. Fault Codes The command f? returns the operating fault. Here are the fault codes: 0 No Fault 1 Flash memory fault 2 Temperature servo fault 3 Input voltage fault 4 Output voltage fault 5 Over current fault More details can be obtained with the fdesc? command. Suppose that f? results in fault code 3, the input voltage fault. The fdesc? then will result in something like: Input voltage low (13.03). If f? returns a 2, meaning temperature servo fault, more information can be obtained using the t0s? (get servo state) command. The servo state codes are: 0 Off 1 Seeking 2 Locked 3 Manual Drive at upper rail too long The TEC drive has been at the upper rail (100%) 101 for too long, and the temperature is not increasing. Drive at lower rail too long The TEC drive has been at the lower rail (0%) for 102 too long, and the temperature is not decreasing.
103 Lost lock The servo was previously locked but has lost the set point and is unable to reacquire it. 104 No convergence to set point The servo was unable to acquire lock. 105 Temperature measurement out of bounds The microprocessor detects a thermistor voltage that is too high, indicating a bad connection to the thermistor. 106 TEC drive hardware fault The circuit that drives the TEC reported a hardware fault. For more information, visit the Fault code page at: http://www.vuemetrix.com/support/tech/faults.html
RS232 Pass Through Feature The RS232 pass through feature allows the TEC Driver to pass messages to another downstream RS232 device. The connection diagram is shown below: The command being passed to the TEC Driver is wrapped inside an! character and a # character. For example, if!sn?># is sent to the TEC driver, the command will be passed to the downstream device as sn?>. The pass through works with USB You can pass the!sn?># command using either the RS232 IN port or the USB port. The pass through expects a reply The downstream device is expected to send some sort of reply immediately. If there is a reply, it will be relayed to the host PC. If there is no reply within a certain amount of time, a passthrough timed out error message will be send to the host PC. Normal RS232 extension cable is to be used between TEC Driver and the RS232 downstream device The RS232 OUT port transmit and receive signals are already reversed compared to the RS232 IN port. This is shown in the Rear Panel Connectors section at the start of this manual. This means that the cable connecting the RS232 OUT port and the downstream device should be a normal extension cable. The null modem cables, where the transmit and receive lines cross over, are not to be used. Do not type the # character in the WinVue Utility Window The pass through feature can be tested in the WinVue Utility window, but do not type the #. Instead, simply type!sn?>. When the WinVue Utility window sees a command starting with the! character, it will attach the # character at the end automatically.
Revision History 1.1.1 Changed connector pin diagrams on page 5 and 6. Re-indexed document. Date 1/19/2010.