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Wavelength Electronics LFI-3751 User Manual

Thermoelectric temperature controller
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LFI-3751 with Autotune PID
Thermoelectric Temperature Controller
The LFI-3751 with Autotune PID is a high performance
temperature controller specifi cally designed for sensitive
applications. Now with Autotune PID capability, the
LFI-3751 automatically optimizes virtually any thermal
load; reduce overshoot or improve temperature stability
with the push of a button.
Key Features . . .
• < 0.002°C temperature stability even at ambient
• Controls temperature with thermistors, RTDs, LM335, or AD590
. . . The Wavelength Advantage
Autotune PID
PID Constants adjustable via front panel
Auto-ranging thermistor & RTD bias current
Bipolar or Unipolar output current operation
High and Low Temperature Limits
Auxiliary temperature sensor input
Analog input allows for external temperature control
(Analog model only)
Addressable RS-232 interface
LFI3751-00400-C Rev D

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Summary of Contents for Wavelength Electronics LFI-3751

  • Page 1 The LFI-3751 with Autotune PID is a high performance temperature controller specifi cally designed for sensitive applications. Now with Autotune PID capability, the LFI-3751 automatically optimizes virtually any thermal load; reduce overshoot or improve temperature stability with the push of a button.
  • Page 2 The Front Panel at a Glance MODEL LFI-3751 Status Section Digi-Pot STATUS Adjust Knob TEMP LIMIT T LIMIT LIMIT I Temp Limit Button REMOTE SENSOR RS-232 ERROR HOLD FOR LOCAL Units of °C Measure 4 Digit Display AMPS VOLTS Display...
  • Page 3 Front Panel Operations at a Glance Operation Legend Limit Current LED Adjusting Limit Current While displayed, Parameter can be changed by rotating Digi-Pot Adjust Knob Positive LIM I Digi-Pot Adjust Knob LIMIT I AMPS is disabled. Monitor ACT T LIMIT I LED fl ashes: SET T TE I parameter only.
  • Page 4 Adjusting RS-232 Address REMOTE SHIFT RS-232 Address RS-232 Displayed while Shift Continuously Button is held. When BEEP BEEP Hold the Shift Button released, new Button address (if changed) is After 3 seconds, REMOTE RS-232 saved and unit beeps. LED lights solid red, unit beeps. Remote RS-232 LED A fl...
  • Page 5 The Front Panel at a Glance Quick Autotune PID Operation Quick Autotune PID Operation decrease Step 1. Adjust the Limit Current below the rated maximum current for your thermoelectric or increase resistive heater. (0.00 to 5.00 Amps) Positive LIM I AMPS ACT T SET T...
  • Page 6 PRESS & sequence varies from load to load. While tuning, RELEASE the ON LED will fl ash. When complete, the LFI-3751 beeps once and the ON LED lights solid. Output Current Autotune Autotune Three audible beeps indicate if the Autotune...
  • Page 7 The Front Panel at a Glance Displaying and Adjusting Values on the Front Panel Display Section SHIFT SHIFT AutS or Autd ACT T °C -199.9°C to +199.9°C (Autotune PID) 0 to 500 k Ω k Ω 1 to 100 Amps / Volt SET T °C OFF (0)
  • Page 8 (5x20mm SLO BLO) provided. Ensure that the via a 16 AWG wire to power source you plug this screw terminal. the LFI-3751 into is properly grounded. LINE: SELECT: 115/230 VAC, 50/60 Hz, 160 VA Wavelength Electronics AC Voltage...
  • Page 9 Specifications. Chapter 5 lists the temperature controller specifi cations. If your LFI-3751 fails within one year of purchase, Wavelength Electronics will repair it free of charge. If you have questions relating to the operation of the LFI-3751, you can contact Technical Support: Call (406) 587-4910 in the U.S.
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  • Page 11: Table Of Contents

    Table of Contents Chapter 1: Quick Start..................13 Preparing the Temperature Controller for Use ..............15 Nine Steps to Operating the LFI-3751 ................17 Chapter 2: Front Panel Operation ..............21 Autotune PID Operation.......................23 Theory of Autotune PID ......................30 Controlling Temperature with Thermistors ................35 Controlling Temperature with RTDs ...................39...
  • Page 12 Standard Command Code Listing ..................82 Calibration Command Code Listing ..................85 Diagnostic Command Code Listing...................86 End Code Listing........................87 Starting RS-232 Communication with the LFI-3751 ............89 Confi guring the Sensor .......................90 Measuring Actual Temperature or Resistance..............94 Setting the Limit Currents ....................95 Setting Temperature Limits ....................96 Autotune PID &...

  • Page 13: Chapter 1: Quick Start

    Chapter 1: Quick Start...
  • Page 14 Chapter 1 - Quick Start Quick Start This chapter shows how to set up an LFI-3751. Become familiar with the temperature controller by following the Nine Steps to Operating the LFI-3751 for a thermoelectric load with a 10 kΩ thermistor temperature sensor. Later chapters expand on this information and offer complete reference information.

  • Page 15: Preparing The Temperature Controller For Use

    Preparing the Temperature Controller for Use The following steps help you verify the temperature controller is ready for use. Verify you have received these items. If anything is missing, contact Wavelength Electronics or your nearest international distributor. One power cord...
  • Page 16 If the controller fails step D or still does not turn on. Call your nearest Wavelength Electronics sales office for instructions on returning the temperature controller to Wavelength for service. In North America, call the factory directly at (406) 587-4910,...

  • Page 17: Nine Steps To Operating The Lfi-3751

    Nine Steps to Operating the LFI-3751 Nine Steps to Operating the LFI-3751 These nine basic steps will familiarize you with the LFI-3751 temperature controller. This example controls a thermoelectric load to 25°C using a 10 kΩ thermistor. Complete details are included in later chapters.
  • Page 18 Chapter 1 - Quick Start Nine Steps to Operating the LFI-3751 Positive LIM I Set Limit Current AMPS With the output off, set the limit current below the thermoelectric’s ACT T SET T maximum current. Assume the example thermoelectric’s maximum...
  • Page 19 Autotune optimization sequence. The ON LED indicator will fl ash while Autotune optimization is in progress. Once the Autotune sequence is fi nished, the LFI-3751 will control to the desired operating temperature entered in Step 5. Refer to Chapter 2, Autotune PID operation for more detail.
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  • Page 21: Chapter 2: Front Panel Operation

    Chapter 2: Front Panel Operation...
  • Page 22 Chapter 2 - Front Panel Operation Front Panel Operation By now, you should be familiar with the Autotune PID feature, how to measure temperature, thermoelectric current & voltage, and how to set various operating parameters. If not, we recommend you read Chapter 1, “Quick Start,”...

  • Page 23: Autotune Pid Operation

    P, I, and D . 1. Autotune Process During an Autotune, the LFI-3751 measures the load’s thermal lag time, L, TE Current the maximum Temperature versus Time slope, R , and the load’s thermal...
  • Page 24 If you are in an electrically noisy environment, don’t use the D term. Use only the P & I terms. • Generally, it is best to choose PID control and let the LFI-3751 determine your control loop method. • For slow thermal loads that cycle around the setpoint even after PI or PID Autotune, select P or PD for the control loop.
  • Page 25 Before Setpoint Response Autotune Setpoint Response Tuning is valuable when continuously stepping the Temp LFI-3751 from one temperature to another. Your system will go to temperature quickly and settle in with little or no overshoot. After Setpoint Response Autotune Time...
  • Page 26 Chapter 2 - Front Panel Operation Autotune PID Operation 4. Confi gure LFI-3751 for Autotune decrease Setpoint Response Tuning • increase Rotate the Display Select Switch to P (Shift Button ON). • While the output current is disabled, rotate the Digi-Pot Adjust Knob Proportional Gain counter-clockwise to change the value displayed to AutS.
  • Page 27 Chapter 2 - Front Panel Operation Autotune PID Operation decrease Disturbance Rejection Tuning increase • Rotate the Display Select Switch to P (Shift Button ON). • While the output current is disabled, rotate the Digi-Pot Adjust Knob Proportional Gain counter-clockwise to change the value displayed to Autd. Wait about two seconds before starting an Autotune sequence.
  • Page 28 Chapter 2 - Front Panel Operation Autotune PID Operation 5. Start Autotune Optimization • Prior to enabling current, the thermoelectric and sensor must be wired to the LFI-3751 output connector, and the current and temperature Output Current limits must be set. Disabled •...
  • Page 29 Correction: Set the limit to something other than zero. E002 – Error 2: Current Limit Cannot Reach SET T • The LFI-3751 determined the current limit is not high enough to reach the desired operating temperature entered in SET T. •...

  • Page 30: Theory Of Autotune Pid

    1. Proportional Gain – “P” and Autotune Optimization TE Current The proportional gain, P, is measured in Amps Output Current per Volt Error Voltage. The Error Voltage is the difference between the LFI-3751’s Setpoint Time When started, D to A and the measured sensor voltage feedback. When a difference exists...
  • Page 31 Chapter 2 - Front Panel Operation Theory of Autotune PID The sensor temperature eventually overshoots the setpoint temperature, forcing the integrator to charge in the opposite direction, reversing the output current. The thermal load’s lag causes an overshoot in this direction also and the cycle simply repeats itself.
  • Page 32 The gears in our car are like the current limit function of the LFI-3751, a lower gear limits our acceleration rate towards the STOP sign and a lower current limit setting decreases how much “gas” we can apply and determines how fast we can approach the stop sign.
  • Page 33 Depending on the size of your load, you may fi nd it good practice to perform a PID Autotune each time the LFI-3751 is powered on to compensate for changes in the thermal load.
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  • Page 35: Controlling Temperature With Thermistors

    = 10.00°C provide this information in a table of Resistance vs. Temperature data. With [A2] = 19.90 kΩ the Steinhart-Hart equation and coeffi cients, the LFI-3751 can calculate [B1] = 25.00°C temperature from thermistor resistance and properly calculate the setpoint [B2] = 10.00 kΩ...
  • Page 36 R = Resistance (Ohms) χ , χ , and χ Typical Thermistor To calculate the Steinhart-Hart coeffi cients, the LFI-3751 needs R vs. T response three (Temperature, Resistance) data pairs. Enter A: (T Resistance kΩ B: (T ), and C: (T ) through the front panel or [A1], [A2], [B1], [B2], [C1], and [C2] via the RS-232 interface.
  • Page 37 Chapter 2 - Front Panel Operation Controlling Temperature with Thermistors decrease increase 5. Entering Data Pair - B Adjust B Enter T [B1] • Rotate the Display Select Switch to B (Shift Button ON) to display the second data pair. °...
  • Page 38 199.9°C Display Actual 8. Displaying Actual Thermistor Resistance Thermistor Resistance • Enter [0.000, 0.000] for A to have the LFI-3751 display thermistor Ω resistance (kΩ) when the Display Select Switch is rotated to ACT T Display Resolution (Shift Button OFF).

  • Page 39: Controlling Temperature With Rtds

    LFI-3751 requires two data pairs B = (T ), C = (T [A2] = 1.000 With the appropriate equation and coeffi cients, the LFI-3751 can calculate [B1] = 0.00°C temperature from RTD resistance and properly calculate the setpoint [B2] = 0.100 kΩ...
  • Page 40 3. RTD Temperature vs. Resistance R vs. T response The LFI-3751 uses three data pairs to confi gure an RTD- A, B, and C. To Resistance (Ω) indicate you’re using an RTD, the fi rst data pair A must be (1.000, 1.000).
  • Page 41 -4.0 x 10 1.41 To use these coeffi cients, rather than the linear confi guration, certain values must be entered for B and C. The LFI-3751 will use the Callendar Van-Dusen coeffi cients if T = 0°C, T = 100°C, = Φ...
  • Page 42 Rotate the Display Select Switch to A (Shift Button ON). The fi rst two data pairs alternate on the display. (1.000, 1.000) °C indicates to the LFI-3751 that you’re using an RTD. • Rotate the Digi-Pot Adjust Knob to change the value ACT T displayed.
  • Page 43 Display Actual RTD Resistance • Enter (1.000, 1.000) for A and (0.000, 0.000) for B to have Ω the LFI-3751 display RTD resistance (kΩ) when the Display Select Switch is rotated to ACT T (Shift Button OFF). • RS-232 Command: [ACT R]...
  • Page 44 Chapter 2 - Front Panel Operation Controlling Temperature with RTDs 9. Adjusting RTD Temperature Setpoint Adjusting RTD Temperature Setpoint decrease • Rotate the Display Select Switch to SET T (Shift Button OFF). Temperature will be displayed. increase • To adjust the setpoint, rotate the Digi-Pot Adjust Knob. While the knob is rotating, the display will change, but the instrument will not °C control to the new setpoint until the knob stops moving.

  • Page 45: Controlling Temperature With An Ad590

    AUX T an output current that varies linearly with temperature. To indicate to the Default AD590 Confi guration LFI-3751 that the sensor is an AD590, A = (2.000, 2.000). To characterize [A1] = 2.000 the linear response, the LFI-3751 requires a Slope and Offset. For the [A2] = 2.000...
  • Page 46 Rotate the Display Select Switch to A (Shift Button ON). Enter [A1] The fi rst two data pairs alternate on the display. (2.000, 2.000) indicates to the LFI-3751 that you’re using an AD590. °C • Rotate the Digi-Pot Adjust Knob to change the value displayed.
  • Page 47 Chapter 2 - Front Panel Operation Controlling Temperature with an AD590 decrease 5. Entering Data Point - C increase Adjust C • Rotate the Display Select Switch to C (Shift Button ON) to Enter Offset [C1] display the AD590 Offset in µA. •...

  • Page 48: Controlling Temperature With An Lm335

    LFI-3751 requires a Slope and Offset. For the LM335, = 3.000 [A1] B = Slope and C = Offset. With this information, the LFI-3751 can calculate [A2] = 3.000 temperature from LM335 voltage and properly calculate the setpoint voltage Slope = 10.00 mV / K...
  • Page 49 • Rotate the Display Select Switch to A (Shift Button ON). Enter [A1] The fi rst two data pairs alternate on the display. (3.000, 3.000) indicates to the LFI-3751 that you’re using an ° C LM335. • Rotate the Digi-Pot Adjust Knob to change the value ACT T displayed.
  • Page 50 Chapter 2 - Front Panel Operation Controlling Temperature with an LM335 decrease 5. Entering Data Point - C increase • Adjust C Rotate the Display Select Switch to C (Shift Button ON) to display the Offset in mV. For the LM335, Offset is 0 mV. Enter Offset [C1] •...

  • Page 51: Controlling Temperature With An Lm35

    LFI-3751 requires a Slope and Offset. For the LM35, = 4.000 [A1] B = Slope and C = Offset. With this information, the LFI-3751 can calculate = 4.000 [A2] temperature from LM35 voltage and properly calculate the setpoint voltage Slope = 10.00 mV /°C...
  • Page 52 Rotate the Display Select Switch to A (Shift Button ON). increase The fi rst two data pairs alternate on the display. (4.000, 4.000) Adjust A indicates to the LFI-3751 that you’re using an LM35. • Enter [A1] Rotate the Digi-Pot Adjust Knob to change the value displayed.
  • Page 53 Chapter 2 - Front Panel Operation Controlling Temperature with an LM35 decrease 5. Entering Data Point - C • Rotate the Display Select Switch to C (Shift Button ON) increase Adjust C to display the Offset in mV. For the LM35, Offset is 0 mV.
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  • Page 55: Sensor Error Condition

    Chapter 2 - Front Panel Operation Sensor Error Condition Sensor Error Condition Sensor Error Process SENSOR ERROR • The Sensor Error LED fl ashes red and the unit beeps whenever the BEEP sensor error condition occurs. The output is forced OFF. •...

  • Page 56: Setting Limit Currents

    TE I TE V • LIM I When the setpoint and actual temperature are different, the LFI-3751 AUX T drives current to the thermoelectric or resistive heater until the load Negative LIM I approaches the setpoint temperature. Sometimes the output current is driven up to the limit current settings (indicated by the LIM I LED fl...

  • Page 57: Setting Temperature Limits

    SENSOR increase RS-232 ERROR HOLD FOR LOCAL • The LFI-3751 uses the lowest number as the Low Temperature LIMIT °C and the highest number as the High Temperature LIMIT. ACT T • HOLD SHIFT FOR The temperature limits will not be updated until the Digi-Pot stops...

  • Page 58: Manually Setting The P, I, And D Constants

    Default P, I, & D Constants PID. Refer to Autotune PID operation on page 23 for a detailed description of the Autotune feature. The LFI-3751 can be confi gured to operate as a P, PI, = 30 PD, or PID temperature controller.
  • Page 59 Chapter 2 - Front Panel Operation Setting the P, I, and D Constants 2. Adjusting the I Term Display Integral • Rotate the Display Select Switch to I (Shift Button ON). Time Constant • Rotate the Digi-Pot Adjust Knob to change the displayed value. •...

  • Page 60: Setting Operating Temperature Or Resistance

    Chapter 2 - Front Panel Operation Setting Operating Temperature or Resistance ACT T SET T Setting Operating Temperature or Resistance TE I TE V LIM I AUX T • Rotate the Display Select Switch to SET T (Shift Button Default Setpoints OFF).

  • Page 61: Enabling Output Current

    Chapter 2 - Front Panel Operation Enabling Output Current Enabling Output Current Thermoelectric 1. Wiring the Output Connector • Wire the thermoelectric or resistive heater to the Output Connector on the rear panel with at least 20 gauge wire. Shielded cables are available (Wavelength part number CAT-220).

  • Page 62: Measuring Thermoelectric Current And Voltage

    Chapter 2 - Front Panel Operation Measuring Thermoelectric Current and Voltage Measuring Thermoelectric Current and Voltage Measuring Thermoelectric Current Display Thermoelectric Current • Rotate the Display Select Switch to TE I (Shift Button OFF). • AMPS Current (in Amps) will be displayed with 10 mA resolution. ACT T SET T •...

  • Page 63: Measuring Auxiliary Thermistor Temperature

    Chapter 2 - Front Panel Operation Measuring Auxiliary Thermistor Temperature Measuring Auxiliary Thermistor Temperature This sensor input is available to monitor the temperature of an auxiliary zone (e.g. heatsink or ambient). It is calibrated to the TCS-610 10 kΩ thermistor and uses a 100 µA bias current.
  • Page 64 Chapter 2 - Front Panel Operation Measuring Auxiliary Thermistor Temperature TCS-610 Temperature vs. Resistance Chart Temperature, Resistance, Temperature, Resistance, °C kΩ kΩ °C 49.67 7.402 47.08 7.098 44.64 6.808 42.34 6.531 40.17 6.267 38.12 6.015 36.20 5.774 34.38 5.545 32.66 5.326 31.04 5.116...
  • Page 65 Chapter 2 - Front Panel Operation Measuring Auxiliary Thermistor Temperature Temperature, Resistance, Temperature, Resistance, °C kΩ °C kΩ 1.638 0.4835 1.584 0.4704 1.532 0.4577 1.482 0.4454 1.433 0.4335 1.387 0.4219 1.342 0.4108 1.299 0.3999 1.258 0.3894 1.218 0.3793 1.179 0.3694 1.142 0.3598 1.106...

  • Page 66: Setting The Rs-232 Address

    Chapter 2 - Front Panel Operation Setting the RS-232 Address Setting the RS-232 Address Default Address RS-232 address: 01 Display RS-232 Address • Press and hold the Shift Button. After three seconds, the RS-232 decrease STATUS address will be displayed. TEMP LIMIT T LIMIT LIMIT I...

  • Page 67: Operating With Resistive Heaters

    The LFI-3751 can be confi gured to deliver only heating current by adjusting the Positive Current Limit to 0.00 Amps. • Since the LFI-3751 has a limited output voltage of 8 Volts at 5 Amps, select a low value resistive heater to use the maximum power from the LFI-3751.
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  • Page 69: Chapter 3: Rear Panel Operation

    Chapter 3: Rear Panel Operation...
  • Page 70 Chapter 3 - Rear Panel Operation Rear Panel Operation This chapter details the sections of the rear panel and provides pinouts for all connectors.

  • Page 71: Connector Pinouts

    Chapter 3 - Rear Panel Operation Connector Pinouts Connector Pinouts 1. Output Connector (9 pin male D-sub plug) • The thermoelectric or resistive heater is wired between pins 1 & 2. Output Connector Regardless of your sensor type, always attach the positive lead of 9 pin male D-sub plug the thermoelectric to pin 1.
  • Page 72 Peripheral Transmit Peripheral Receive Signal Ground RS-232 Output The RS-232 output connects to another Wavelength Electronics RS-232 Input instrument with addressable RS-232 interface. The RS-232 OUTPUT (25 pin female D-sub receptacle) always connects to the other instrument’s RS-232 INPUT connector.

  • Page 73: Bnc Connector

    Chapter 3 - Rear Panel Operation BNC Connector BNC Connector [Used with Analog Version only] Analog Input BNC Analog Input BNC Input a 0 to ±10 V analog signal to adjust the setpoint remotely. The sum of the front panel SET T setting and analog input determine the control temperature.

  • Page 74: Ac Power

    Chapter 3 - Rear Panel Operation AC Power AC Power 1. AC Power Entry Module The AC Power Entry Module on the rear panel is designed to accept input voltages from 98 to 133 and 196 to 265 VAC. Ensure that the power source you plug the temperature controller into is properly grounded.

  • Page 75: Chapter 4: Remote Interface Reference

    Chapter 4: Remote Interface Reference...
  • Page 76 Chapter 4 - Remote Interface Reference Remote Interface Reference This chapter details the RS-232 hardware, command and response packet structure, and how to use each command. Command codes and error codes are also listed. All example command strings assume the instrument’s RS-232 address is 01.

  • Page 77: Rs-232 Interface Confi Guration

    RS-232 Interface Confi guration RS-232 Interface Confi guration You connect an LFI-3751 to the RS-232 interface using the 25-pin D-sub serial connector (DB-25) on the rear panel (RS-232 Input Connector). You can add up to 98 more LFI-3751s by connecting the RS-232 Output Connector on the rear panel of the fi...
  • Page 78 1. Connections to a Computer • Pins 5, 6, 8, and 20 on the LFI-3751 RS-232 Input Connector are shorted at the connector to ensure that the computer serial port is properly confi gured to transmit and receive data. Pin 4 on the 9 pin D-Sub male plug (Data Terminal Ready Out) provides the appropriate handshaking to the computer’s Data Carrier Detect In (pin 1), Data Set Ready In (pin 6),...
  • Page 79 DB-25 DB-25 DB-25 Male Female Male Female D-Sub Shell on LFI-3751 is connected to chassis. Always properly earth ground the LFI-3751 chassis through your AC power system. 3. Controlling Multiple Instruments via RS-232 DB-9 To Host Computer or DB-25 4. RS-232 Connector Pinouts...

  • Page 80: Rs-232 Command And Response Packet Formats

    Chapter 4 - Remote Interface Reference RS-232 Command and Response Packet Formats RS-232 Command and Response Packet Formats • The host computer sends a Command Packet to the instrument and the temperature controller returns a Reponse Packet to the host computer. A Response Packet always returns after each Command Packet is sent.
  • Page 81 Chapter 4 - Remote Interface Reference RS-232 Command and Response Packet Formats Command Packet Command Unit Command Command Start Type Unit # Type Code Data ± X X X 7 6 5 4 3 2 1 0 Data Field Characters Response Packet Response Unit...

  • Page 82: Standard Command Code Listing

    Chapter 4 - Remote Interface Reference Standard Command Code Listing Standard Command Code Listing Command Command Command Type Code Description and Data Field Range ACT T Actual Temperature Measurement ACT R Actual Sensor Resistance Measurement 1 or 2 SET T Temperature Setpoint: -199.900 to +199.900°C 1 or 2 SET R...
  • Page 83 Chapter 4 - Remote Interface Reference Standard Command Code Listing Command Command Command Type Code Description and Data Field Range Alarm Status Char 7 = Sign Char [+ always] Char 6 = Sensor Open Error [0 = OK, 1 = Error] Char 5 = Sensor Short Error [0 = OK, 1 = Error] Char 4 = Low Temperature Limit [0 = OK, 1 = Error] Char 3 = Decimal Point...
  • Page 84 Chapter 4 - Remote Interface Reference Standard Command Code Listing Command Command Command Type Code Description and Data Field Range HALT Turns all lamps off, disables interrupts, and shuts off all timers, PROCESSOR clocks, and watchdog then freezes the CPU. Remove power to reset unit.

  • Page 85: Calibration Command Code Listing

    Chapter 4 - Remote Interface Reference Calibration Command Code Listing Calibration Command Code Listing • All WRITE Command Packets are PASSWORD protected. Command Command Command Type Code Description & Data Field Range 10 µA BIAS CAL Enter actual 10 µA sensor bias current in µA 1 or 2 Enter actual 100 µA sensor bias current µA 100 µA BIAS CAL...

  • Page 86: Diagnostic Command Code Listing

    Chapter 4 - Remote Interface Reference Diagnostic Command Code Listing Diagnostic Command Code Listing Command Command Command Type Code Description and Data Field Range LAMP CONTROL Turns Front Panel Lamps on and off. Char 7: Sign Char [+ = manual, - = automatic] Char 6: Sequence Lamps [0 = OFF, 1 = Lamp ON] To check the lamps, Char 5: All Lamps ON [0 = OFF, 1 = Lamp ON]...

  • Page 87: End Code Listing

    Chapter 4 - Remote Interface Reference End Code Listing End Code Listing End Code Description Normal Ending - No errors Command Type not supported (Valid values are ‘1’ or ‘2’) Illegal ASCII digit contained in Command Code or FCS fi eld Data fi...
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  • Page 89: Starting Rs-232 Communication With The Lfi-3751

    Chapter 4 - Remote Interface Reference Starting RS-232 Communication with the LFI-3751 Starting RS-232 Communication with the LFI-3751 Once you have connected a computer and at least one LFI-3751, set the unit’s RS-232 address from the front panel. 1. Set RS-232 address...

  • Page 90: Confi Guring The Sensor

    (Sets [C2]) • The table on the next page details the Command Codes and expected data for all the sensors supported by the LFI-3751. • To read the current sensor confi guration, the Command Type changes from a WRITE (2) to a READ (1): Read !101121+000.00026...
  • Page 91 Chapter 4 - Remote Interface Reference Confi guring the Sensor Command Codes and Expected Data to Confi gure Supported Sensors Sensor Type RS-232 Command Command Code Data Description Data Range Thermistor [A1] Temperature 1 -199.900 to +199.900°C [A2] Resistance 1 +000.000 to +499.900 kΩ...
  • Page 92 Chapter 4 - Remote Interface Reference Confi guring the Sensor 2. Selecting Automatic or Manual Sensor Bias • Each sensor type needs a different bias. The following table details the typical settings for each type of sensor. See Chapter 2 for a thorough RS-232 discussion of each sensor type.
  • Page 93 Chapter 4 - Remote Interface Reference Confi guring the Sensor • When writing the [Sensor Bias Confi guration] command, Character 7 (+ or -) confi gures the instrument to manual or automatic mode. A ‘+’ puts the sensor confi guration under manual control. A ‘-’...

  • Page 94: Measuring Actual Temperature Or Resistance

    Chapter 4 - Remote Interface Reference Measuring Actual Temperature or Resistance Measuring Actual Temperature or Resistance RS-232 • To measure actual sensor temperature from an instrument, send the Commands Discussed: following Command Packet. [ACT T] [ACT R] Read (Reads [ACT T] in °C) !101101+000.00024 •...

  • Page 95: Setting The Limit Currents

    Chapter 4 - Remote Interface Reference Setting the Limit Currents Setting the Limit Currents For complete detail about setting the Limit Current, see Chapter 2. RS-232 Commands Discussed: • Separate positive and negative current limits are available: [LIM I POSITIVE] [LIM I POSITIVE] and [LIM I NEGATIVE].

  • Page 96: Setting Temperature Limits

    Chapter 4 - Remote Interface Reference Setting Temperature Limits Setting Temperature Limits RS-232 For complete detail about setting the Temperature Limits, see Chapter Commands Discussed: 2, page 59. [T LIM HIGH] [T LIM LOW] • Separate high and low temperature limits are available to protect your load: [T LIM HIGH] and [T LIM LOW].

  • Page 97: Autotune Pid & Setting The P, I, And D Constants

    Setpoint Response Autotuning or to reject thermal transient effects on temperature stability by using Disturbance Rejection Autotuning. The LFI-3751 can be configured to operate as a P, PI, PD, or PID temperature controller. •...
  • Page 98 Chapter 4 - Remote Interface Reference Setting the P, I, and D Constants • To configure the instrument as a PD controller with P = 30 and D = 1 second, send the following Command Packets. Write !101210+030.00024 (Sets [P] to 30) !101211+000.00026 (Sets [I] to OFF) !101212+001.00024...

  • Page 99: Setting Temperature Setpoint

    Chapter 4 - Remote Interface Reference Setting Temperature Setpoint Setting Temperature Setpoint For complete detail about setting the Operating Temperature, see RS-232 Commands Discussed: Chapter 2. [SET T] • To confi gure the instrument with a temperature setpoint of 35°C, send the following Command Packet.

  • Page 100: Setting Resistance Setpoint

    Chapter 4 - Remote Interface Reference Setting Resistance Setpoint Setting Resistance Setpoint • RS-232 To use resistance as the setpoint, you must be using a resistive sensor: Commands Discussed: thermistor or RTD. The following table shows the confi guration settings and Command Packets to set the confi...

  • Page 101: Enabling And Disabling The Output Current

    Chapter 4 - Remote Interface Reference Enabling and Disabling the Output Current Enabling and Disabling the Output Current For complete detail about Enabling the Output Current, see Chapter 2. RS-232 Commands Discussed: 1. Enable Current [RUN / STOP] • To enable the instrument’s output current send the following Command Packet.

  • Page 102: Measuring Thermoelectric Current And Voltage

    Chapter 4 - Remote Interface Reference Measuring Thermoelectric Current and Voltage Measuring Thermoelectric Current and Voltage RS-232 For complete detail about measuring thermoelectric current and voltage, Commands Discussed: see Chapter 2. [TE I] • To measure the thermoelectric current out of the instrument, send the [TE V] following Command Packet.

  • Page 103: Measuring Auxiliary Sensor Temperature

    Chapter 4 - Remote Interface Reference Measuring Auxiliary Sensor Temperature Measuring Auxiliary Sensor Temperature RS-232 For complete detail about measuring temperature with the auxiliary sensor, Commands Discussed: see Chapter 2. [AUX T] • To measure temperature of the auxiliary 10 kΩ thermistor wired to the instrument, send the following Command Packet.

  • Page 104: Setting Gain For Analog Input Signal (Rear Panel Bnc Connector)

    Chapter 4 - Remote Interface Reference Setting Gain for Analog Input Signal (Rear Panel BNC Connector) Setting Gain for Analog Input Signal (Rear Panel BNC Connector) RS-232 • The instrument automatically sets the gain of the Analog Input Connector Commands Discussed: to match your sensor and bias current confi...

  • Page 105: Checking The Alarm Status

    Chapter 4 - Remote Interface Reference Checking the Alarm Status Checking the Alarm Status RS-232 • To monitor the status of the Sensor Error, Temperature Limits, Current Commands Discussed: Limits, and Output Current, use the [Alarm Status] command. To read the Alarm Status of the instrument, send the following Command [Alarm Status] Packet.

  • Page 106: Halting The Processor

    Chapter 4 - Remote Interface Reference Halting the Processor Halting the Processor • RS-232 The [HALT PROCESSOR] command turns all front panel lamps off, Commands Discussed: disables interrupts, shuts off all timers, clocks, and the watchdog then freezes the CPU. To stop the processor on the instrument, send the [HALT PROCESSOR] following Command Packet.

  • Page 107: Reverting To Local Mode

    Chapter 4 - Remote Interface Reference Reverting to LOCAL Mode Reverting to LOCAL Mode • RS-232 To switch from computer to front panel control of the instrument, use Commands Discussed: the [LOCAL] command. To revert to LOCAL mode, send the following Command Packet.

  • Page 108: Entering The Password

    This data fi eld does not follow the standard format. These eight characters are only restricted to ASCII characters. • The PASSWORD can be obtained by calling Wavelength Electronics Technical Support or your local distributor. • To read the status of PASSWORD access, send the following Command Packet.

  • Page 109: Reading Serial & Model Numbers, Firmware Version

    (Reads Serial Number ‘XXXXXXXX’) • To read the instrument’s Firmware Version, send the following Command Packet. Read !101156+000.00026 (Reads Firmware Version ‘XXXXXXXX’) • To read the instrument’s Model Number, send the following Command Packet. Read !101157+000.00027 (Reads Model Number ‘XXXXXXXX’; should return “LFI-3751”)

  • Page 110: Calibration - Sensor Bias Current And Ad590 Sense Resistance

    To change these calibrated values, you must fi rst send [PASSWORD] the [PASSWORD] command. You should not use these commands [10 µA BIAS CAL] without direct supervision from Wavelength Electronics Technical Support [100 µA BIAS CAL] Group. [1 mA BIAS CAL]...
  • Page 111 Chapter 4 - Remote Interface Reference Calibration - Sensor Bias Current and AD590 Sense Resistance RS-232 Calibrating the 10 mA Reference Current Commands Discussed: • If the instrument’s 10 mA reference current is actually 10.262 mA, send [10 mA BIAS CAL] the following Command Packet to properly calibrate the unit.

  • Page 112: Calibration- Act T, Te I, Te V Uncalibrated Voltages

    Chapter 4 - Remote Interface Reference Calibration - ACT T, TE I, TE V uncalibrated voltages Calibration- ACT T, TE I, TE V uncalibrated voltages RS-232 Reading the uncalibrated ACT T voltage Commands Discussed: • This command reads the uncalibrated ACT T voltage from the instrument’s [RAW ACT T VOLT] A/D.

  • Page 113: Calibration - Measurement Slopes & Offsets

    Commands Discussed: calibrated values, you must fi rst send the [PASSWORD] command. You should not use these commands without direct supervision from [PASSWORD] Wavelength Electronics Technical Support Group. [ACT T SLOPE CAL] [ACT T OFFSET CAL] Write [TE I SLOPE CAL]...
  • Page 114 Chapter 4 - Remote Interface Reference Calibration - Measurement Slopes & Offsets Reading the ACT T, TE I, TE V Slopes and Offsets • To read the measurement calibration settings, the Command Type changes from a WRITE (2) to a READ (1) and no [PASSWORD] is required: Read !101174+000.00026 (Reads [ACT T SLOPE CAL])

  • Page 115: Calibration - Set T Slopes & Offsets

    Commands Discussed: these calibrated values, you must fi rst send the [PASSWORD] command. You should not use these commands without direct supervision from [PASSWORD] Wavelength Electronics Technical Support Group. [POS SET T SLOPE CAL] [POS SET T OFFSET CAL] Write...

  • Page 116: Calibration - Te Limit Current Slopes & Offsets

    fi rst send the [PASSWORD] command. You should not use these commands without direct supervision from [PASSWORD] Wavelength Electronics Technical Support Group. [T POS LIM I SLOPE CAL] [T POS LIM I OFFSET CAL] Write...

  • Page 117: Restore Calibration Defaults

    To issue this command you must fi rst send the [PASSWORD] command. Commands Discussed: You should not use this command without direct supervision from Wavelength Electronics Technical Support Group. To revert this [PASSWORD] instrument back to the default settings, send the following Command [RESTORE FACTORY Packets.

  • Page 118: Diagnostic - Lamp Control

    Chapter 4 - Remote Interface Reference Diagnostic - Lamp Control Diagnostic - Lamp Control • RS-232 The [LAMP CONTROL] command tests whether the LEDs or 7 segment Commands Discussed: displays are properly operating. [LAMP CONTROL] • Six test states are provided. The following table details the structure of the characters in the data field.

  • Page 119: Diagnostic - Switch Status

    Chapter 4 - Remote Interface Reference Diagnostic - Switch Status Diagnostic - Switch Status Output, Shift, and Temp Limit Pushbutton Status RS-232 Commands Discussed: • The following table details the structure of the characters in the data fi eld [PUSHBUTTON SWITCH for the [PUSHBUTTON SWITCH STATUS] command.

  • Page 120: Diagnostic - Digi-Pot Status

    Chapter 4 - Remote Interface Reference Diagnostic - Digi-Pot Status Diagnostic - Digi-Pot Status • RS-232 The [DIGIPOT STATUS] command reads whether the Digi-Pot is moving Commands Discussed: clockwise or counterclockwise and quantifi es how far it has rotated since it was last cleared. [DIGIPOT STATUS] •...

  • Page 121: End Code Reference

    Chapter 4 - Remote Interface Reference End Code Reference End Code Reference 00 - Normal Ending Command in the Command Packet has been processed correctly and Response Packet contains valid data. Data is not valid if any other End Code is returned. 01 - Command Type Not Supported Fifth character of the Command Packet (Command Type) contains a character other than ‘1’...
  • Page 122 ASCII value was transmitted. 26 - Query Calculation Error The LFI-3751 was unable to calculate the requested measurement. Data in the Response Packet is ‘+999.999’. This occurs when the sensor is open or shorted. This also occurs when the sensor is improperly confi gured or out of the temperature range.

  • Page 123: Calculating Fcs

    Chapter 4 - Remote Interface Reference Calculating FCS Calculating FCS • FCS (Frame Check Sum) is used to assure that the RS-232 transmission was not corrupted. • The following BASIC routine calculates the FCS for a Command or Response Packet. 1110 ‘Copy either Command$ or Response$ into Packet$ BASIC Routine for...

  • Page 124: Example Basic Control Program For Ibm Pc Compatible Machines

    Example BASIC Control Program for IBM PC Compatible Machines Example BASIC Control Program for IBM PC Compatible Machines 1000 ‘ LFI-3751 RS-232 Control Program for IBM PC Compatible Machines 1001 ‘ 1002 ‘ Confi gure the COM Port #1 for RS-232 communications with the following settings 1003 ‘...
  • Page 125 Chapter 4 - Remote Interface Reference Example BASIC Control Program for IBM PC Compatible Machines 1032 ‘ Calculate the Frame Check Sum (FCS) for the entered command 1033 ‘ 1034 FCS=0 1035 FOR IFCS=1 TO LEN(COMMAND$) 1036 FCS=FCS XOR ASC(MID$(COMMAND$,IFCS,1)) 1037 NEXT 1038 FSC$=RIGHT$(“0”+HEX$(FCS),2) 1039 ‘...
  • Page 126 Chapter 4 - Remote Interface Reference Example BASIC Control Program for IBM PC Compatible Machines 1063 ‘ The following loop sums the COM port buffer to create a response packet. 1064 ‘ If 21 characters are detected in the COM port buffer, then the response packet is 1065 ‘...

  • Page 127: Chapter 5: Specifi Cations

    Chapter 5: Specifi cations...
  • Page 128 Chapter 5 - Specifi cations Specifi cations This chapter details the General, Electrical, and Mechanical Specifi cations of the LFI-3751 Temperature Controller.

  • Page 129: General Specifi Cations

    Chapter 5 - Specifi cations General and Electrical Specifi cations General Specifi cations 115 / 230 ±15% VAC Power Supply: Acoustic Noise: 26 dBa (Switch Selectable) Warm-Up Time: 1 hour Power-Line Frequency: 60/50 Hz Warranty: 1 year standard Power Consumption: 160 VA peak 25 Watt average (Output Off) Remote Interface:...

  • Page 130: Mechanical Specifi Cations

    Chapter 5 - Specifi cations Mechanical Specifi cations Mechanical Specifi cations 12.00" [305mm] MODEL LFI-3751 STATUS 6.50" [165mm] ACT T SET T TE I 7.10" [180mm] TE V LIM I AUX T SENSOR OUTPUT 5 Amp - 40 Watt Temperature Controller Wavelength Electronics 12.65"...

  • Page 131: Appendix

    Appendix: CAT-220 Cable Accessory Diagram...

  • Page 132: Appendix Cat-220 Cable Accessory Diagram

    Appendix CAT-220 Cable Accessory Diagram CAT-220 Cable Accessory Diagram CAT-220 Description Wire color TEC + TEC - BLACK Aux Sensor + BROWN Sensor - GREEN Main Sensor + WHITE AD590 Voltage ORANGE Fan - YELLOW Fan+ (+12 V) BLUE -12 V PURPLE SHELL SLATE...

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