RMT Ltd. Thermoelectric Cooler Controller DX5100 Quick Start Instruction RMT Ltd. Moscow, 2013 Version 1.02 RMT Ltd. Controller DX5100. Quick Start. Table of Contents How to Get Connected ........................................................................................................................ 3 DX5100 Vision .................................................................................................................................... 4 Thermistor Setting ............................................................................................................................... 4 Procedure Description ..................................................................................................................... 5 Choose the type of thermistor ......................................................................................................... 6 Calibration of Temperature Measurement Channel ............................................................................ 7 Controller Firmware Version <= 333. .............................................................................................. 7 Controller Firmware Version >= 334 .............................................................................................10 Viewing Current Settings of Thermistor. Checking Measurements ..............................................11 Verification of the function of temperature calculation ..................................................................14 Checking Temperature Measurement Channel ............................................................................15 PID Tuning ........................................................................................................................................16 AUTO-PID FUNCTION ..................................................................................................................16 Introduction ................................................................................................................................16 Ziegler-Nichols Algorithm ..............................................................................................................16 PID TUNING TIPS .........................................................................................................................17 SETTING ALARM LIMITS.................................................................................................................20 Setting Limits of TEC Voltage .......................................................................................................20 Setting Temperature Limit Values .................................................................................................21 Version 1.02 / 2013 Page 2 / 21 RMT Ltd. Controller DX5100. Quick Start. How to Get Connected Assemble the module of the Controller according to the functional scheme and connecting procedure described in ”Technical Manual”, Sections 3, 4. Since the Controller is two-channel, if the Boards of Converters DX5102 are available, be careful matching appropriate Boards and channels. Connect the Thermoelectric Cooler (TEC), observing polarity. The positive polarity corresponds to the cooling mode. Note: The connector for TEC connection is XP4 of the Power Board DX5102 or one of the connectors XP4 or XP2 of the double-channel Board DX5105. Connection is made by the cable given in the delivery set of the Power Board in conformity with the connector description (see the Technical Manual). Mind the polarity. Important! For a proper functioning of an object of regulation it is necessary to provide effective heat rejection from the TEC hot side. It is achieved by a heat sink (probably with induced cooling) with good thermal contact of the TEC hot side and the heat sink surface. Important! It is necessary to provide a good thermal contact of the thermistor with the regulation object (TEC). The place of the thermistor should be chosen as close as possible to the cooled surface of the TEC to provide the minimal transport delay. The transport delay is the time after the moment of the voltage change to the moment of reception of the feedback signal - the change of temperature caused by this voltage change. By default the Command interface is RS-232. Connect the Device to a COM-port of your PC by the cable RS-232 given in the Standard Kit of the Digital Control Board. The connection should be made to the connector XP8 of the Digital Control Board. In case you have got an interface Converter USB-RS485 DX5106 and want to use the interface RS-485 as the Command one, make connection of the Digital Control Board DX5101 to DX5106 by a twisted pair and the cable RS-485. It is necessary to observe polarity. Connectors XP7 and XP8 DX5101 - RS-485 interface Pin 1 2 Description Signal A of the interface RS-485 Signal B of the interface RS-485 Connectors XP1 and XP2 DX5106 - RS-485 interface Pin 1 2 3 4 Description Signal A of the interface RS-485 Signal B of the interface RS-485 Supply voltage of the galvanic isolation is 12 V. Polarity does not matter. At zero voltage the operation is possible. Connect a Power Supply. It should provide voltage 12±10% V. Note: The Power Supply is connected to the connector XP1 of each Power Board DX5102, or to the connector XP5 of the Power Board DX5105. Important! Power source should be chosen based on the total power of the Power Boards of the Controller and additional power consumption if the Controller is idling (Specification). If the maximal power required for a given TEC (I max and Umax) are lower than the maximal characteristics of the Power Boards of the Controller, the the power source can be chosen with a smaller total power. Version 1.02 / 2013 Page 3 / 21 RMT Ltd. Controller DX5100. Quick Start. Important! For correct operation of the board DX5102 and DX5105 should provide them with proper cooling, possibly forced (with fans). Hardware current limit allows briefly slightly exceed the maximum allowed under current specifications . However, you should absolutely avoid long-term operation of the board at a current exceeding the allowable specification . In the case of passive cooling when the board is located without cover, with the orientation of elements - up, at ambient temperature isn't more than 25C - electric power (per channel ) mustn't exceed half of the maximum capacity. Under the conditions that impair the natural convection - this power is reduced. DX5100 Vision Install the DX5100 Vision program supplied or downloaded from the manufacturer's website http://rmtltd.ru/downloads/. 1 By default, the controller has a rate setting 19200 kbps . When you run the program, it scans the serial ports of the system and determines the connected devices DX5100. Select the device to work with, press the button "Open". Pay attention to the version of the controller firmware. The algorithm of thermistor setting depends on the version number. Thermistor Setting Attention! It is strongly recommended to back up the parameters of the controller before adjusting the thermistor. See "Backup/restore of parameters". 1 If you want to change the connection speed, see item 1.3. Parameters of Controller DX5100. User's Guide. Version 1.02 / 2013 Setting Communication Page 4 / 21 RMT Ltd. Controller DX5100. Quick Start. Procedure Description The thermistor setting means finding and storing parameters of the ADC channels for each thermistor in the non-volatile memory. The procedure for setting a thermistor can be divided into several stages: Determination of input data: o thermistor type, o nominal, o choice of function type to calculate temperature o calculation (or entering) coefficients, o storage of coefficients in controller. 2 ( ), Calibration of temperature measurement channel: o o Controller firmware version <= 333 3 calibrating resistors supplied should be used, cable of four-wire resistance measurement circuit. Controller firmware version >= 334 You can choose "automatic" calibration; You can calibrate in the manual mode, as in the version 333; Verification of measurement results. 2 The controller allows using 2 types of functions for calculating temperature versus resistance: • Polynomial 5th order function: ( ) Steinhart-Hart equation: ( ) 3 During calibrating, the program will inform you on the required nominal values (depending on thermistor type). You can also use other resistors of similar resistance values. Version 1.02 / 2013 Page 5 / 21 RMT Ltd. Controller DX5100. Quick Start. Choose the type of thermistor To ease the setup procedure, the program offers a choice of predefined characteristics of thermistors. The list includes the parameters for 4 platinum thermistors and 47 NTC thermistors with different alpha and beta coefficients. If you have chosen a thermistor from the list, you can go to the next section, "Calibration of temperature measurement channel". You may check the results of calculations by using the button "Calc". . If necessary, if your thermistor is not listed, you can use the point "User defined". The program will prompt you to choose a type of function for calculating temperature and operating temperature 4 range . 4 The ambient temperature must fall within the operating temperature range, but if you are sure it does, you can disable the checking of this condition. Version 1.02 / 2013 Page 6 / 21 RMT Ltd. Controller DX5100. Quick Start. When you select the Steinhart-Hart equation, you will be asked to enter 3 points of the dependence of temperature on resistance. This information is usually provided by a thermistor manufacturer. The extreme points should be at the edges of the working range, while the average - in the middle. The distance between points must be at least 10 degrees. When choosing a polynomial function of temperature calculation you are supposed to enter the coefficients. That's enough to start the calibration of temperature measurement channel. You may check the results of calculations of the function of calculating temperature by pressing "Calc". Calibration of Temperature Measurement Channel Controller Firmware Version <= 333. Connect the cable of four-wire resistance measurement circuit to the XP4 connector of the board DX5101-200. At the end of the cable there should be a connector that allows changing quickly the calibration resistors. calibration resistor XP3 or XP4 1 2 3 4 Sensor connection cable (for DX5101-200) Version 1.02 / 2013 From contacts 1 and 2 From contacts 3 and 4 Page 7 / 21 RMT Ltd. Controller DX5100. Quick Start. Now we can proceed with the calibration. For example, consider a commonly used platinum thermistor Pt 1000 (3.75E-03). Click the button "Calibrate". The program will ask for the confirmation. After the positive answer the calibration procedure is started. The program asks to connect the jumper in the place of the thermistor (the connector of the cable of the four-wire resistance measurement circuit). Version 1.02 / 2013 Page 8 / 21 RMT Ltd. Controller DX5100. Quick Start. Set the jumper, click "Ok". The program will do the zero calibration and ask you to connect the calibration resistance of the closest nominal, but not greater than the value calculated. Connect the resistance 1500 Ohm (supplied). Click "Ok". The program will ask for the nominal value of the resistor connected (Ohm). Write 1500 and click "Ok". The program prompts you to connect another resistor of a smaller value. Connect the resistor 750 Ohm. Click "Ok". The program will ask for the nominal value of the resistor connected again (Ohm). Write 750. Click "Ok". Version 1.02 / 2013 Page 9 / 21 RMT Ltd. Controller DX5100. Quick Start. The procedure of setting the thermistor parameters and calibrating temperature measurement channel is 5 completed . Controller Firmware Version >= 334 Since the calibration procedure of the measurement channel has been carried out by the manufacturer, you need only select your thermistor type and value: After clicking the "Calibrate' button and confirming the start of the calibration procedure: 5 If you failed to do something, you can always carry out the calibration procedure again, or reset the controller parameters from the backup file, see Chapter "Procedure of Restoring from Backup". Version 1.02 / 2013 Page 10 / 21 RMT Ltd. Controller DX5100. Quick Start. You will be prompted to select a mode: The manual mode is described above; In the automatic mode, the parameters set in the controller will match your thermistor. Viewing Current Settings of Thermistor. Checking Measurements If necessary, you can get the current thermistor settings and assess the accuracy of measurements. Click the button "Show current Thermistor settings". Version 1.02 / 2013 Page 11 / 21 RMT Ltd. Controller DX5100. Quick Start. The program will read from the controller a type of the function used and its coefficients, and try to identify a thermistor connected. In the case of coincidence of the coefficients with those predefined, on the following information will be displayed the screen: If the coefficients are not identical (an unknown thermistor), the program will build a graph of temperature versus resistance, and determine the thermistor nominal by the obtained coefficients (for platinum thermistors at Т = 0 °С, for NTC thermistors at Т = 25°С). Version 1.02 / 2013 Page 12 / 21 RMT Ltd. Version 1.02 / 2013 Controller DX5100. Quick Start. Page 13 / 21 RMT Ltd. Controller DX5100. Quick Start. Verification of the function of temperature calculation Using the input field for temperature or resistance in the block "Check function of approximation" you can verify if the calculated values agree with the experimental ones. For example, the temperature dependence of an NTC Thermistor -10kOhm is given by a table. For the temperature range 273K…328K by the table lines of 273K, 298K and 328K we find the factors A, B, and C of the Steinhart and Hart equation, as the law describing NTC thermistors most accurately. T (K) R (Ohm) 273 278 283 288 293 298 303 308 313 318 323 328 35670 27230 20960 16260 12710 10000 7920 6320 5070 4090 3320 2710 A B C 1.305550E-03 2.147652E-04 9.227314E-08 Choose item "User defined → "Steinhart and Hart equation", set the nominal value 10,000 Ohm. Enter three points from the table: In the field "R[Ohm]:" enter the resistance values from the table, click the button "Calc". Repeat the calculation for each point of the original table. Obtain the results of temperature calculation: Initial Data R[Ohm] 35670 27230 20960 16260 12710 10000 7920 6320 5070 4090 3320 2710 T[K] 273 278 283 288 293 298 303 308 313 318 323 328 → Calculation T = f(R) R[Ohm] T[K] 273 35670 278,01 27230 283,01 20960 288,01 16260 293 12710 298 10000 303 7920 307,99 6320 312,99 5070 318 4090 323 3320 328 2710 It is also possible to carry out a reverse calculation: enter temperature, and calculate resistance. Version 1.02 / 2013 Page 14 / 21 RMT Ltd. Controller DX5100. Quick Start. In the field "T[K]:" enter the temperature from the table, click the button "Calc". Repeat the calculation for each point of the original table. Initial Data R[Ohm] T[K] 35670 273 27230 278 20960 283 16260 288 12710 293 10000 298 7920 303 6320 308 5070 313 4090 318 3320 323 2710 328 → Inverse calculation of R R[Ohm] T[K] 35670 273 27242 278 20970 283 16266 288 12709 293 10000 298 7922 308 6316 308 5067 313 4090 318 3320 323 2710 328 Checking Temperature Measurement Channel The block "Measurement of the resistance of the thermistor" allows checking the temperature measurement channel. Connect the resistor with which the calibration was done. Click "Measurement", as a result we obtain the current values for checking. The main field here is "ADC [hex]". The controller applies a 24-bit ADC. Hence, the full scale (the nominal value of the resistance, which we entered in the calibration) corresponds to the value FFFFFFh. It should be close to this value, but not equal, otherwise it will be perceived as an overflow. For checking, we carry out the measurements about 10 times and observe this parameter. Version 1.02 / 2013 Page 15 / 21 RMT Ltd. Controller DX5100. Quick Start. PID Tuning To fine-tune the PID controller there is a tab: Here you can set the PID controller coefficients, plot the setpoint attaining curve at different values of the coefficients. The controller has a built-in function "AUTO-PID". When using it, you may get the initial values of the coefficients. AUTO-PID FUNCTION INTRODUCTION The finding of optimum parameters of regulation of the given object is quite a delicate and long procedure. It is a consecutive experimental choice of parameters. At the same time the quality of regulation of temperature depends on the optimality of the set parameters. Attention! The parameters preset at the device delivery are formal and do not concern a real controlled object. With the purpose of simplification of the PID controller optimum parameters choice in the ТЕС Controller DX5100 the function auto-PID is realized. This function realizes the known Ziegler-Nichols algorithm. The user applying this function can use the obtained PID controller parameters for the subsequent accurate adjustment or apply the given parameters directly to the control of the object. Attention! Before starting the auto-PID function it is necessary to set thermoelectric module maximal allowable voltage. Attention! Nevertheless the manufacturer regards the parameters obtained with the help of the built-in auto-PID function as estimated and not quite optimum. It is recommended to check up the obtained parameters and if necessary to carry out a more accurate tuning of the PID parameters depending on the required quality of the thermal regulation. Ziegler-Nichols Algorithm In the Controller DX5100 one of the known algorithms of an automatic finding of the PID parameters is realized. When the object of regulation is exposed to voltage (current) of a certain value the dynamic characteristic of the object of regulation is obtained as the parameters of its transition into a stationary condition at a given influence. The figure below illustrates the dynamics of the process and the required parameters. Version 1.02 / 2013 Page 16 / 21 Controller DX5100. Quick Start. dP RMT Ltd. dU t D t The required parameters are: D - Deadtime - Process gain K dU D dP The found values of the specified parameters by the Ziegler-Nichols method enable to estimate the PID parameters as: Proportional coefficient 1,2 х K Integral coefficient 2x Differential coefficient 0,5 x D D PID TUNING TIPS The tuning quality can be estimated by different criteria: by the rate of achieving the setpoint, by the minimal overshot, by accuracy of setpoint maintenance. The tuning quality can also be estimation by the transient process of achieving the setpoint. Recommendations for PID tuning by the form of the starting curve are given below. 1. Set values of integrated and differential components equal to zero: Ki=0; Kd=0 Modify the value of the proportional component factor so that the form of the transitive characteristic correspond that of curve 2 or 3. Version 1.02 / 2013 Page 17 / 21 RMT Ltd. Controller DX5100. Quick Start. Kp1>Kp2>Kp3>Kp4>Kp5 Ttarget T0 2. Modify the value of the differential component factor so that the form of the transitive characteristic correspond that of curve 2. Ttarget T0 3. The integrated component is intended to remove a residual mismatch between the temperature value achieved in the system and the setpoint. Modify the value of the proportional component factor so that the form of the transitive characteristic correspond that of curve 3. Ttarget T0 Version 1.02 / 2013 Page 18 / 21 RMT Ltd. Version 1.02 / 2013 Controller DX5100. Quick Start. Page 19 / 21 RMT Ltd. Controller DX5100. Quick Start. SETTING ALARM LIMITS Setting Limits of TEC Voltage Important! To prevent a thermoelectric cooler (TEC) failure, it is necessary to set correct limit values of TEC voltage. Refer to the TEC specifications. Version 1.02 / 2013 Page 20 / 21 RMT Ltd. Controller DX5100. Quick Start. Setting Temperature Limit Values The tab "Limiting temperatures" allows you to specify the maximum and minimum temperatures. If temperature is beyond these limits within the time specified, a corresponding alarm is on and PID control is off, - the alarm conditions. The meaning of the parameters to be set is explained by the following picture. Version 1.02 / 2013 Page 21 / 21