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Lake Shore 372 User Manual

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User's Manual
Model 372
AC Resistance Bridge and
Temperature Controller
Lake Shore Cryotronics, Inc.
sales@lakeshore.com
575 McCorkle Blvd.
service@lakeshore.com
Fax: (614) 891-1392
Westerville, Ohio 43082-8888 USA
www.lakeshore.com
Telephone: (614) 891-2243
Methods and apparatus disclosed and described herein have been developed solely on company funds of
Lake Shore Cryotronics, Inc. No government or other contractual support or relationship whatsoever has existed
which in any way affects or mitigates proprietary rights of Lake Shore Cryotronics, Inc. in these developments.
Methods and apparatus disclosed herein may be subject to U.S. Patents existing or applied for.
Lake Shore Cryotronics, Inc. reserves the right to add, improve, modify, or withdraw functions, design modifications,
or products at any time without notice. Lake Shore shall not be liable for errors contained herein or for incidental or
consequential damages in connection with furnishing, performance, or use of this material.
Rev. 1.9
P/N 119-372
12 March 2019
|
www.lakeshore.com

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  • Page 1 Lake Shore Cryotronics, Inc. reserves the right to add, improve, modify, or withdraw functions, design modifications, or products at any time without notice. Lake Shore shall not be liable for errors contained herein or for incidental or consequential damages in connection with furnishing, performance, or use of this material.
  • Page 2 (b) the Product is fit for any particular purpose expressly or 2.Lake Shore warrants the Product only if the Product has been sold impliedly made known to Lake Shore at the time of the conclusion of by an authorized Lake Shore employee, sales representative, dealer or the contract.
  • Page 3 WinZip™ is a registered trademark of Nico Mak of Connecticut. changes made to the firmware. Copyright 2014-2019 Lake Shore Cryotronics, Inc. All rights reserved. No portion of this manual may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the express written permission of Lake Shore.
  • Page 4 Overvoltage Category II Pollution Degree 2 EN 61326-1:2013 Class A Controlled Electromagnetic Environment EN 50581:2012 Signed for and on behalf of: Place, Date: Westerville, OH USA Scott Ayer 29-SEP-2016 Director of Quality & Compliance Model 372 AC Resistance Bridge and Temperature Controller...
  • Page 5 Scott Ayer 29-SEP-2016 Although the Model 372 itself does not contain any of the restricted materials listed in the RoHS directive, the Director of Quality & Compliance Model 3708 does. This causes the model numbers listed on this page to be not RoHS compliant.
  • Page 6 To qualify for the CE Mark, the Model 372 meets or exceeds the requirements of the European EMC Directive 89/372/EEC as a CLASS A product. A Class A product is allowed to radiate more RF than a Class B product and must include the follow- ing warning: WARNING:This is a Class A product.

  • Page 7: Table Of Contents

    1.7.9 Lake Shore CX-1010-SD with 0.01 to 325 K Calibration....13 1.7.10 372/3726 Performance Specification Table....... 14 1.7.11 372/3708 Performance Specification Table.
  • Page 8 2.5.1 Why is the Model 372 Called a Bridge? ....... .
  • Page 9 3.5.3 Sensor Lead Cable ............59 3.5.4 Driven Guards .
  • Page 10 6.5.2 Ethernet Firmware Updater ..........144 Model 372 AC Resistance Bridge and Temperature Controller...
  • Page 11 8.14.1 Contacting Lake Shore ........
  • Page 12 Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 13: Chapter 1: Introduction

    1.1 Model 372 Features Chapter 1: Introduction FIGURE 1-1 Model 372 front view 1.1 Model 372 Patented noise rejection technology Highly versatile and reliable measurement input Features Ability to increase the number of measurement channels to a maximum of 16...

  • Page 14: Introduction

    The measurement signal cables use a driven guard that reduces parasitic capaci- tance in the cables that connect a scanner to the Model 372. This helps to further balance the measurement network and bolster the integrity of the noise rejec- tion circuitry.

  • Page 15: Temperature Measurement

    3726 scanner, up to 17 sensors can be connected simultaneously, each with their own curve. 1.3.6 Measure a Wide With up to 21 different current (I) excitation levels available, the Model 372 is able to perform accurate impedance measurements from several microohms(10 )) to...

  • Page 16: Expandability

    3726 scanner, preserving the signal-to-noise ratio between the sensor and measurement circuitry of the Model 372. This allows connection cables of up to 10 m to be used between the Model 372 and the 3726.

  • Page 17: Dilution Refrigerator Temperature Control

    1.4 Dilution Refrigerator Temperature Control 1.4 Dilution Accurate measurement at ultra-low temperatures are no easy feat, especially when working in the ranges seen by modern dilution refrigerators. The Model 372 has Refrigerator many features specifically developed for dilution refrigerator applications.

  • Page 18: Multiple Heater Options

    1.4.3 Stable When operating at ultra-low temperatures, even small amounts of added energy can cause unwanted spikes in system temperature. The Model 372 heater outputs imple- Temperature Control ment several protection mechanisms to reduce or eliminate this potential: The circuitry for the sample and still heaters are electrically isolated from other...

  • Page 19: Heater Fail-Safes

    1.4.5 Heater Fail-Safes 1.4.5 Heater Fail-Safes The Model 372 has several features that will protect your system and experiment from accidental deviations in planned temperature settings: Temperature thresholds can be set for all heater outputs, meaning the heaters will automatically shut down if it is detected that the system is being overheated.

  • Page 20: Low-Power Impedance Characterization: The 3708 Scanner

    To accomplish this, the 3708 produces higher levels of DC bias current than both the Model 372 and the 3726 scanner and preamp. This means the 3708 would cause self- heating in a temperature sensor used at ultra-low temperatures. The new dedicated control input resolves this issue by providing the ability to make highly-reliable mea- surements of a temperature control sensor.

  • Page 21: Lower Input Voltage Noise

    1.5.1 Lower Input The limiting factor for making extremely low-impedance measurements directly with the Model 372 is the input voltage noise figure of 10 nV/xHz. The preamp in the Voltage Noise 3708 reduces this by a factor of 5 to an impressive 2 nV/xHz. By reducing the amount of input noise, even smaller return signals can be recovered with excellent accuracy.

  • Page 22: Connectivity And Usability-Communication Options

    Emulation mode on the Model 372 is designed to imitate all important commu- nication functions of the Model 370. In most cases, programming that was previ- ously written for the Model 370 can be used to interact with the Model 372. A convenient heater connector adapter (117-071) can also be purchased that...

  • Page 23: Sensor Performance

    Control Catalog for more information. 1.7.5 Interpolation Interpolation errors are due to the linear interpolation method used by the Model 372 to convert resistance values to temperatures when using a temperature errors sensor. These errors are not present when resistance is measured directly.

  • Page 24: Lake Shore Rox™-102B-Cb With 0.02 To 40 K Calibration

    102B-CB with 0.02 to 40 K Calibration FIGURE 1-13 Sensor performance for Lake Shore Rox™-102B-CB with 0.02 to 40 K calibration 1.7.8 Lake Shore GR-50- Values given are for measurement input. If the value is different for the control input, it is shown in blue.

  • Page 25: Lake Shore Cx-1010-Sd With 0.01 To 325 K Calibration

    Values given are for measurement input. If the value is different for the control input, it is shown in blue. 1010-SD with 0.01 to 325 K Calibration FIGURE 1-15 Sensor performance for Lake Shore CX-1010-SD with 0.01 to 325 K calibration www.lakeshore.com...

  • Page 26: 372/3726 Performance Specification Table

    These cells contain bracketed Performance numbers to indicate the resolution that applies to the control input Specification Table FIGURE 1-16 372/3726 performance specification table Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 27: 372/3708 Performance Specification Table

    1.7.11 372/3708 Performance Specification Table 1.7.11 372/3708 Performance Specification Table FIGURE 1-17 372/3708 performance specification table www.lakeshore.com...

  • Page 28: Specifications

    1: Introduction HAPTER 1.8 Specifications See section 1.8.1 through section 1.8.10 for specifications for the Model 372. 1.8.1 Measurement Input type AC, four-lead differential, resistance Number of inputs Input Maximum channels 16 (with optional scanner) Measurement units ), K (with temperature curve) Resistance ranges 22 ranges from 2 m) to 63.2 M) (excitation depen-...

  • Page 29: Control Input

    1.8.2 Control Input Connectors 6-pin DIN (current out), 6-pin DIN (voltage in), and DA-15 (scanner control) Supported scanners Lake Shore 3726 and 3708 1.8.2 Control Input Input type AC, four-lead differential, resistance Number of inputs Measurement units ), K (with temperature curve)

  • Page 30: Warm-Up Heater Output

    ±2.5 mV <0.003% of range Noise (resolution) Monitor output settings Scale User selected Data source Temperature or sensor units Input, source, top of scale, and bottom of scale Settings Connector Detachable terminal block Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 31: Heater Control

    1.8.7 Heater Control 1.8.7 Heater Control Number of control loops 2 (sample heater, warm-up heater) Update rate Tuning Manual PID, zone PID control settings Proportional (gain) 0.0 to 1,000 Integral (reset) 0 to 10,000 s Derivative (rate) 0 to 2,500 s Manual output 0 to 100% with 0.01% setting resolution Zone control...
  • Page 32 435 mm W × 89 mm H × 368 mm D (17 in × 3.5 in x 14.5 in), full rack Weight 6.8 kg (15 lb) Approval CE mark Scanner size 135 mm W × 66 mm H × 157 mm D (plus connector clear- ance of 125 mm) Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 33: Safety Summary And Symbols

    When installing the instrument in a desktop environment, ensure it is mounted on a flat, level surface. Improper Use If the instrument is used in a manner that is not specified by Lake Shore, the safety protections provided by the instrument are no longer guaranteed, and may be impaired.
  • Page 34 Earth (ground) terminal CAUTION or WARNING: See instrument documentation; background color: yellow; Protective conductor terminal symbol and outline: black Frame or chassis terminal On (supply) Off (supply) FIGURE 1-18 Safety symbols Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 35: General

    With careful installation of a high quality bridge like the Model 372 it is not difficult to achieve 50 mK. Below that, each detail of the overall system has to be optimized to a low end of between 5 and 20 mK.

  • Page 36: Cryogenic Cooling System Terminology

    Terminology below 1 K. This is an attempt to demonstrate how the Model 372 can be integrated into these systems for resistance measurement, temperature measurement and tem- perature control. It is hoped that from these examples, those knowledgeable in cryo- genic techniques will become familiar with the terminology used throughout this manual and the intended operation of many of the instrument features.

  • Page 37: He Cryostat

    2.4.2 3He Cryostat few milliwatts of heat from a resistive heater to sustain evaporation. The Model 372 still output can drive the still heater. This is a good location for a diagnostic temperature sensor. Heat exchangers: one or more heat exchangers serve to cool returning He rich liquid to near the temperature of the mixing chamber.

  • Page 38: Adiabatic Demagnetization Refrigerator (Adr)

    There has recently been growing interest in the tech- Demagnetization nology and it is finding its way into many new applications. The Model 372 has many Refrigerator (ADR) features that can help automate and control these systems in temperature ranges where leaded resistance measurement is practical.

  • Page 39: Model 372 Theory Of Operation

    (cooling). The construction of the switch varies depending on temperature but could be superconducting, exchange gas (gas-gap) or mechanical. Several types of heat switches can be controlled by the Model 372 still heater or analog output. Salt pill: this is a mass of paramagnetic salt that acts as the refrigerant. It is mag- netized while in thermal contact with the precooling stage so the heat of magne- tization is removed and entropy is reduced.

  • Page 40: Resistance Measurement

    “bridge” was retained to reflect the instrument’s heritage of precision resis- tance measurements. 2.5.2 Resistance The Model 372 uses a four lead, AC sine wave measurement technique to achieve the best possible accuracy with the lowest possible excitation. Similar circuits are used Measurement extensively in small signal measurement because they are flexible and can extract small signals from relatively noisy environments.

  • Page 41: Reactance Measurement

    (real) and the capacitive/inductive reactive component (imaginary) is called impedance. The Model 372 uses an on-board digital signal processor to digitally synthesize the excitation current used for measurements. In addition, the Model 372 has the capability to measure both the resistive, in-phase voltage and the reactive, out of phase voltage measured across the load.

  • Page 42: Resistance Ranges

    2.5.5.2 Control Input The Model 372 control input has full-scale resistance ranges from 2 k up to 632 k. Unlike the measurement input, the excitation current is a function of the selected resistance range.

  • Page 43: Measurement Circuit

    Most parts of a good strategy are obvious, some are not and even the best plans do not work all the time. The Model 372 offers several features that help control noise and maintain signal integrity. The ideas and instrument features described in this manual often have to be tried in different combination to get the best results.
  • Page 44 2.5.6.3 Electrical Isolation The precision analog front end of the Model 372 is electrically isolated from digital circuitry and chassis of the instrument by opto-couplers. This can improve measure- ments in two ways. First, isolation makes it more difficult for digital noise from con- trol circuits and computer interfaces to affect the measurement leads.

  • Page 45: Measurement Speed And Filtering

    2.5.6.6 Matched Impedance Current Source The Model 372 takes the idea of a differential input one step further with a unique feature in its current source. The two current source output terminals have the same source impedance, similar to the voltage input terminals of a differential input that have the same input impedance.

  • Page 46: Noise Sources

    More specific installation instructions are given in Chapter 3. The Model 372 offers a diag- nostic monitor voltage output that can be helpful in diagnosing noise related prob- lems.

  • Page 47: Analog Circuit Noise

    2.6.4 Digital Circuit All digitally controlled instruments emit some high-frequency noise both through the air and on their leads. Emission from a Model 372 is very low and will not affect resis- Noise tance measurements or heat measured resistors if the instrument is installed prop- erly.

  • Page 48: Interference Between Two Model 372S

    Error 2.7.1 Warm Up and When the Model 372 is first turned on it should be allowed to warm up for at least 30 min before use to allow its internal temperature to stabilize. Warm up is an exagger- Temperature Drift ated form of temperature drift because the temperature change inside the enclosure is larger and faster than would be experienced in a laboratory setting.

  • Page 49: Lead Resistance

    Low excitation frequencies Capacitance were chosen for the Model 372 to minimize this effect but capacitance can still con- tribute to measurement error when resistance is high. Driven guards should be used when measuring resistance above 100 k), but they often cannot be used inside of the cryostat and are not available for scanner input leads.
  • Page 50 , the following equation can be used: measured measured As an example, if the Model 372 is displaying the a complex impedance reading of: 66.50 – j15.30 k) Because of the large negative reactive component, it is concluded that there is a large parasitic capacitance in the test setup.

  • Page 51: Instrument Operation

    If noise is not suspected as a potential problem, it may be easier to measure the effect of self-heating using the many current ranges available in the Model 372 than to try to calculate thermal resistance.

  • Page 52: Excitation Vs. Signal-To-Noise

    The digital phase sensitive detector (PSD) in the Model 372 is a very narrow band pass filter. The output of the PSD is run through a digital low-pass filter with 200 ms time constant to give an equivalent, sampled DC voltage.

  • Page 53: 3726 And 3708 Scanner

    2.9 3726 and 3708 The 3726 scanner expands the input capability of the Model 372 from 1 to 16 chan- nels. The 3708 expands the input capability of the Model 372 from 1 to 8 channels Scanner and provides an even lower noise, low resistance measurement.

  • Page 54: Scanner Performance

    The channel change settling time of the 3726 and 3708 scanners are virtu- ally the same as the range change settling time of the Model 372. Additional time may be required for the instrument to autorange if that feature is enabled and the resistance on the new channel changes significantly between scans.
  • Page 55 1.7 µK at 50 mK to 83 µK at 1 K. The reason that the drop in resolution is not as severe as the drop in sensitivity is that excitation current is increased approximately 1,000 times by the Model 372 to maintain practical measurement parameters. Sensi- tivity (and therefore resolution) of most sensors changes with temperature so it is important to choose a sensor with high sensitivity in the most critical temperature range.

  • Page 56: Sensor Calibration

    2.10.2 Sensor The Model 372 can convert the resistance of a sensor to temperature, using either lin- ear or cubic spline interpolation methods, if a temperature response curve is loaded Calibration into the instrument.

  • Page 57: Sensor Installation

    Model 372 user curve loca- tions. You can also use it to read curves from the Model 372 and save them to files. There are two versions of the Curve Handler™ application. The fully featured version is a 32-bit Microsoft Windows™...
  • Page 58 The lead wire must be an electrical conductor, but should not be a good thermal conductor, or heat will transfer down the leads and change the temperature reading of the sensor. Model 372 AC Resistance Bridge and Temperature Controller...
  • Page 59 2.10.3 Sensor Installation Small 30 to 40 AWG wire made of an alloy like Manganin or phosphor bronze is much better than copper wire. Super conducting wire is a good choice if wire temperature remains below the transition temperature. Thin wire insulation is preferred for better heat sinking.

  • Page 60: Temperature Control

    2: Cooling System Design and Temperature Control HAPTER 2.11 Temperature The Model 372 includes a dedicated control input to perform closed-loop tempera- ture control in a dilution refrigerator or other low power cryogenic cooling system. Control The load must be equipped with a temperature sensor for feedback and a resistive heater to add heating power into the system.

  • Page 61: Closed Loop Pid Control

    To do this, it uses feedback from the control sensor to calculate and actively adjust the control (heater) output. The Model 372 uses a control algorithm called PID that refers to the three terms used to tune the controller for each unique system.
  • Page 62 2.11.2.4 Manual Output The Model 372 has a control parameter that is not a normal part of a PID control loop. Manual output can be used for open loop control, meaning feedback is ignored and the heater output stays at the user’s manual setting.

  • Page 63: Tuning A Closed Loop Pid Controller

    2.11.3 Tuning a Closed Loop PID Controller FIGURE 2-5 Examples of PID control 2.11.3 Tuning a Closed There has been a lot written about tuning closed loop control systems and specifically PID control loops. This section does not attempt to compete with control theory Loop PID Controller experts.
  • Page 64 It is common for systems to require two or more heater ranges for good control over their full temperature. Lower heater ranges are normally needed for lower temperature. The Model 372 is of no use controlling at or below the temperature reached when the heater was off.
  • Page 65 Use the oscillation period of the load that was measured above in seconds as the integral setting. Enter the integral setting into the Model 372 and watch the load temperature approach the setpoint. If the temperature does not stabilize and begins to oscillate around the setpoint, the integral setting is too low and should be doubled.
  • Page 66 2: Cooling System Design and Temperature Control HAPTER Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 67: Chapter 3: Installation

    Instruments themselves may be shipped as several parts. The items included with the Model 372 are listed below. Contact Lake Shore immediately if there is a shortage of parts or accessories. Lake Shore is not responsible for any miss- ing items if not notified within 60 days of shipment.

  • Page 68: Rear Panel Definition

    FIGURE 3-2 Line input assembly 3.4.1 Line Voltage The Model 372 has four different AC line voltage configurations so that it can be oper- ated from line power anywhere in the world. The nominal voltage and voltage range of each configuration is shown below. (The recommended setting for 230 V operation is 240 V.)

  • Page 69: Line Fuse And Fuse Holder

    3.4.2 Line Fuse and Fuse Holder AC line voltage is set at Lake Shore, but it is good to verify that the AC line voltage indica- tor in the fuse drawer window is appropriate before turning the instrument on. The instrument may be damaged if turned on with the wrong voltage selected.

  • Page 70: Measurement Input Connector Definition

    — Tied to measurement common The Model 372 makes an AC resistance measurement; therefore, the + and – signs are to aid in proper lead arrangement and not indicate signal polarity. TABLE 3-2 Diode/resistor input connector details 3.5.2 Control Input One 6-pin (240°) circular DIN 45322 receptacle is used for the resistive control input.

  • Page 71: Sensor Lead Cable

    The driven guards are only available for the measurement input and are always active. If you do not wish to use guarding, ensure that the guard conductors of the cable are not connected to the Model 372 guard pins. Pin Name...

  • Page 72: Isolation And Grounding

    (Obviously this will not shield noise generated within the Dewar.) In many installations the best noise performance of the Model 372 can be achieved when the cable shield is tied directly to the Dewar or other large conductive mass sur- rounding the experimental space.

  • Page 73: Dressing Cables

    3726 scanner. In the 3708 scanners, these are left open. Please take this into account when installing the Dewar wiring. Model 372 scanner and measurement circuitry is isolated from the earth ground. There- fore, connecting shields at both the scanner and Dewar does not result in a “ground loop.”...

  • Page 74: Temperature Sensors

    One difference is that four lead devices are normally calibrated with a specific Sensors arrangement of current and voltage leads. Follow all manufacturer recommenda- tions on installation, including lead arrangement, or errors in temperature measure- ment will result. Model 372 AC Resistance Bridge ands Temperature Controller...

  • Page 75: Optional Scanner Installation

    3.6 Optional Scanner Installation 3.6 Optional The 3726 and 3708 scanners expand the input capability of the Model 372 and increase the number of input channels to 16 (3726) or 8 (3708). It is an extension of Scanner the isolated measurement circuitry of the Model 372 so its installation should follow Installation the guidelines described in section 3.5 as well as this paragraph.

  • Page 76: Scanner Output Connector Definition

    These are identical to the connectors used on the Connector Definition measurement input of the Model 372. The cables included with the scanner are ade- quate for most installations. In the event that you must make a cable for a special application, connector pin definition on the scanner is identical to the input connec- tor definition given in section 3.5.1.
  • Page 77 3.6.5 Scanner Output Cabling Female Male DB15 DB15 Shield not To scanner To Model 372 attached FIGURE 3-11 Scanner to instrument measurement cable www.lakeshore.com...

  • Page 78: Scanner Control Connector Definition

    The cable must have one connector plug end to mate with the instrument, and one connector receptacle end to mate with the scanner. Model 372 AC Resistance Bridge ands Temperature Controller...

  • Page 79: Using The Scan Control Signals Without A Scanner

    3.6.8 Using the Scan Control Signals without a Scanner 3.6.8 Using the Scan If an optional scanner is not installed, some of the scan control lines are available for other uses. These signals remain part of the isolated measurement circuitry and Control Signals without should be treated like part of the resistance measurement.

  • Page 80: Scanner Mounting Bracket

    4 MM (0.156 IN) DIA THRU-HOLE (9 PLACES) b) 4 MM (0.156 IN) DIA THRU-HOLE; C’SINK 7 MM (0.28 IN) DIA (4 PLACES) Scanner mounting bracket with a sample hole pattern FIGURE 3-14 Model 372 AC Resistance Bridge ands Temperature Controller...

  • Page 81: Heater Output Setup

    PID control algorithm, to balance the continuous cooling power of the refrigera- tion system and maintain steady load temperature. The sample heater on the Model 372 has eight current ranges scaled in approximate one-third steps. Each range will source one-tenth the power of the next largest range with the highest range being 1 W.

  • Page 82: Heater Output Connectors

    3.7.2 Heater Output A 7-pin detachable terminal block is used to connect the sample and warm-up heat- ers to the Model 372. One 7-pin terminal block is included in the connector kit Connectors shipped with the Model 372. This is a common connector, and additional mating con- nectors can be purchased from electronics suppliers, or from Lake Shore as P/N 106- 765.

  • Page 83: Heater Output Isolation

    Dewar at a sin- gle point. 3.7.5 Heater Output The warm-up heater output circuitry in the Model 372 is capable of sourcing 10 W of power. This type of circuitry can generate some electrical noise. The Model 372 is Noise...

  • Page 84: Calculating Still Heater Current

    If the diagnostic monitor output is configured for the control input ADC signal, the reference output will produce the control input reference frequency. Sec- tion 8.12 provides more information on how to configure and use this output. Model 372 AC Resistance Bridge ands Temperature Controller...

  • Page 85: Chapter 4: Operation

    4.1 General This chapter provides instructions for the general operating features of the Model 372 AC resistance bridge and temperature controller. Advanced operation is in Chapter 5. Computer interface instructions are in Chapter 6. FIGURE 4-1 Model 372 front panel 4.1.1 Understanding...

  • Page 86: Front Panel Description

    (FIGURE 4-1). The direct operation keys provide one touch access to the most often used functions of the Model 372. The number pad keys, with the exception of the dec- imal point key, are dual function keys. If the instrument is in the number entry mode, the keys are used to enter numbers.

  • Page 87: Annunciators

    4.2.2 Annunciators Function Refer to section Press this key to navigate menus, and to select parameters.In addition, this key will allow the user  to navigate to a temporary display screen to view scan channels/inputs that aren’t presently dis- 4.2.3 played.

  • Page 88: General Keypad Operation

    The intuitive front panel layout and keypad logic, bright, graphic display, and LED indicators enhance the user-friendly front panel interface of the Model 372. The Model 372 offers a bright, graphic, vacuum fluorescent, (VF) display that can simulta- neously display up to eight readings at once.

  • Page 89: Display Overview

    (section 4.3.3). 4.3.1.3 Temporary Reading Display Mode Independent of the configured display mode, the Model 372 provides the capability to enter into a temporary display mode using the  and  keys. This allows the user to scroll through the latest enabled measurement input channel readings and the control input reading.

  • Page 90: Display Modes

    Interface command: RDGSTL? 4.3.2 Display Modes The Model 372 provides several display modes designed to accommodate different instrument configurations and user preferences. The measurement input display mode provides detailed information about the active measurement input channel sensor. The control input display mode provides detailed information about the con- trol input.
  • Page 91 4.3.2 Display Modes The top half of the display provides information related to the sensor input. The input channel number is displayed, followed by the user-assignable input name. The sensor reading is displayed in large character format, using the units assigned to the respec- tive input’s preferred units parameter.

  • Page 92: Control And Scan Information Display Quadrant

    Information Display independent of display mode. In addition, it can be configured to display the active Quadrant measurement input scan channel. Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 93: Display Brightness

    4.3.4 Display Brightness When this display quadrant is configured to active scan channel mode, the channel designator and channel name are displayed in small characters while the reading is displayed in large characters. The following figure shows the active measurement channel displayed in the lower left quadrant.

  • Page 94: Input Setup

    HAPTER 4.4 Input Setup With no scanner attached, the Model 372 input setup menu will display only the con- trol input (A) and the measurement input (1) as available for configuration. If an optional 8-channel 3708 or 16-channel 3726 scanner is attached, the input setup menu will expand the measurement input to display measurement input channels 1 through 8 or 1 through 16.

  • Page 95: Resistance Range Selection

    4.4.2 Resistance Range Selection To change the current excitation, use the Current Excitation  and  keys. Available ranges are listed in Chapter 1. As the range table indicates, not every combination of current excitation and resistance range is possible. The following messages are dis- played in the excitation display to indicate limits.

  • Page 96: Autorange

    HAPTER 4.4.2.1 Turning Excitation Off The Model 372 offers many excitation levels with the lowest being very low in power. It is still sometimes necessary to turn excitation off. Excitation should be turned off any time the current source leads are open-circuited and then attached to a cold resistor with the instrument turned on.

  • Page 97: Optional Scanner Setup

    Default: Off Interface command: INTYPE 4.4.4 Optional Scanner The Model 372 automatically identifies the 3708 or 3726 scanner when it is powered up with the scanner attached. When the scanner is attached, operation related to the Setup measurement input changes slightly. This section summarizes scanner operation although most of the operation is addressed in the individual feature paragraphs.

  • Page 98: Filter

    This required the filter to re-populate with enough readings to meet the settle time requirement before a settled reading was presented. The Model 372 also contains a new feature that allows the filter settle time to be adjusted without having to reset the filter. For example, if the reading is settled and the settle time is changed from 60 s to 30 s, the newly configured filtered reading is instantly provided.

  • Page 99: Temperature Coefficient

    Interface command: INSET 4.4.9 Input Name To increase usability and reduce confusion, the Model 372 provides a means of assigning a name to each of the inputs as well as each scanner channel if a scanner is attached. The designated input name is used on the front panel display whenever possible to indicate which sensor reading is being displayed.

  • Page 100: Curve Selection

    1 to 20. In order for existing 370 con- trol software to read and write curves from locations 1 to 20, the Model 372 must be placed into emulation mode (section 5.8). When in emulation mode, the firmware will translate the 370 curve locations received over the remote interface to adhere to the new curve location numbering scheme.

  • Page 101: Instrument Setup

    The Model 372 offers four alternate nominal frequencies of 9.8 Hz, 11.6Hz, 16.2 Hz, and 18.2 Hz, with the control input by default being assigned 16.2 Hz. Frequency can be changed through firmware without turning the instrument off;...

  • Page 102: Active Common Mode Reduction

    Default: On Interface command: CMR 4.5.3 Monitor Output The monitor output on the Model 372 is a tool to help the user diagnose measure- ment problems. The output can be set to monitor test voltages from several points Selection inside the instrument. The monitor voltages are often used with the reference output.
  • Page 103 Interface command: HTRSET 4.6.1.2 Warm-up Heater Max Current and Heater Resistance The Model 372 warm-up heater output is designed to work optimally into a 25 ) or 50 ) heater. The Heater Resistance and Max Current parameters work together to limit the maximum available power into the heater.
  • Page 104 The heater output display is a calculated value intended to aid in system setup and tun- ing. It is not a measured value, and may not accurately represent actual power in the heater. Model 372 AC Resistance Bridge and Temperature Controller...
  • Page 105 To do this, it uses feedback from the control input sensor to calculate and actively adjust the control output setting. The Model 372 uses a control algorithm called PID that refers to the three terms used to tune the control. Refer to section 4.6.1.5.1 for details on assigning a control input for the closed loop feedback.
  • Page 106 A control loop consists of a control output for controlling the temperature, and an input for feedback into the control algorithm. Use the Control Input parame- ter to assign the control input sensor to the desired output. Model 372 AC Resistance Bridge and Temperature Controller...
  • Page 107 4.6.1 Heater Outputs In the Monitor Out mode the control input parameter is used to determine the source of the output voltage. A special case exists when a scanner is attached, autoscanning is enabled, and a mea- surement input channel is selected as an output’s control input. Details regarding the change to the control algorithm as a result of this special case are described in section 4.6.1.6.1.
  • Page 108 In addition, when an output is configured for Open Loop mode, the Manual Output setting is available in the Output Setup menu. Menu navigation: Sample Heater or Warm-Up Heater Q PID/Man Out Q Manual Output Q (0% to 100%) Model 372 AC Resistance Bridge and Temperature Controller...
  • Page 109 There are some instances when temperature control in ohms may be desired, for example when a temperature curve is not available. For these applications the Model 372 can control temperature in ohms. To control in ohms, set the preferred units parameter to ohms. When controlling in ohms, the setpoint resolution matches the display resolution for the sensor input type given in the specifications (section 1.6.1).
  • Page 110 HAPTER 4.6.1.5.7 Setpoint Ramping The Model 372 can generate a smooth setpoint ramp when the preferred units are expressed in temperature. You can set a ramp rate in degrees kelvin per minute with a range of 0 to 100 and a resolution of 0.001. Once the ramping feature is turned on, its action is initiated by a setpoint change.
  • Page 111 The Model 372 can be forced to read only the specified measurement input control channel for a period of time after any setpoint change to guarantee settling.
  • Page 112 It is equivalent to setting the heater range parameter of all outputs to Off. This function is always active even if the keypad is locked or when it is in remote mode. Model 372 AC Resistance Bridge and Temperature Controller...
  • Page 113 While use of the dedicated control input is the preferred method of temperature con- trol, the Model 372 and 3726 scanner allow both temperature control and data col- lection at the same time using just the scanner without the dedicated control input.

  • Page 114: Analog Output

    100 ) can drive the output into current limit. This condition will not damage the out- put, but it can result in discontinuous temperature control. 4.6.2.1 Monitor Out Refer to section 5.4 for more information on Monitor Out mode. Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 115: Power Up Enable

    4.6.3 Power Up Enable 4.6.2.2 Still Output Mode The Model 372 can provide the small amount of power required to drive the still heater of a dilution refrigerator with the analog output. None of the analog output hardware changes when it is configured for still operation. Section 3.8.2 describes how to estimate the full scale current sourced to a resistive heater.

  • Page 116: Ethernet

    The advantages of using the Ethernet interface include the ability to communi- cate directly with the Model 372 from any PC on the same local network, and even from around the world via the Internet. Refer to section 6.4.1 for details on Ethernet configuration.

  • Page 117: Chapter 5: Advanced Operation

    5.1 General Chapter 5: Advanced Operation 5.1 General This chapter provides information on the advanced operation of the Model 372 AC resistance bridge and temperature controller. 5.2 Zone Settings The Model 372 allows you to establish up to ten custom contiguous temperature zones where the controller will automatically use pre-programmed values for PID, heater range, manual output, ramp rate, and relay 1 and 2 states.
  • Page 118 Manual output Heater Range Ramp Rate A On A Off Relay 1 (0.0–1,000) (0–10,000) (0–2,500) (0–100%) (0.001–100 K/min) Zone 01 A On A Off Relay 2 FIGURE 5-1 Record of zone settings Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 119: Warm Up Mode

    5.3 Warm Up Mode Menu navigation: Zone Settings Q Sample Heater or Warm-up Heater Q Zones Q (1 to 10) 5.3 Warm Up Mode The warm-up heater comes with a selectable warm-up mode that is designed to drive a heater to rapidly increase the temperature in a controlled system, for example, to bring a system to room temperature in order to change samples.

  • Page 120: Monitor Out

    +10 V in either unipolar or bipolar modes. Input Lowest Middle Highest Bipolar –10 V +10 V Output Input mode Input Lowest Middle Highest Unipolar +5 V +10 V Output FIGURE 5-2 Unipolar and bipolar mode Model 372 AC Resistance Bridge and Temperature Controller...
  • Page 121 5.4.1 Monitor Units For example, if Polarity is set to Bipolar, then setting the Monitor Out –10 V parameter to 0 K and the Monitor Out +10 V parameter to 100 K will cause the analog output to correspond to the input temperature as shown in FIGURE 5-3. In this case if the actual reading was 50 K, then the output would be at 0 V (middle of the scale).

  • Page 122: Alarms And Relays

    The two relays on the Model 372 can also be tied to alarm functions as described in section 5.5.2. You may want to set the Visible parameter to Off if there is no need for showing the alarm state on the front panel, for instance, if you are using the alarm function to trig- ger a relay.
  • Page 123 5.5.1 Alarms non-latching operation. With the high alarm setpoint at 100 K and the dead band at 5 K, the high alarm triggers when sensor input temperature increases to 100 K, and it will not deactivate until temperature drops to 95 K. In addition, the same 5 K dead band is applied to the low alarm setpoint as well.

  • Page 124: Relays

    HAPTER 5.5.2 Relays There are two relays on the Model 372, numbered 1 and 2. They are most commonly thought of as alarm relays, but they may also be manually controlled. Two relays can be used with one sensor input for independent high and low operation, or each can be assigned to a different input.

  • Page 125: Curve Numbers And Storage

    5.6 Curve Numbers and Storage 5.6 Curve The Model 372 has 20 standard curve locations, numbered 1 through 20. At present, not all locations are occupied by curves; the others are reserved for future updates. If Numbers and a standard curve location is in use, the curve can be viewed using the view operation.

  • Page 126: Curve Breakpoints

    Enter the breakpoints with the sensor units value increasing as point number increases. There should not be any breakpoint locations left blank in the middle of a curve. The search routine in the Model 372 interprets a blank breakpoint as the end of the curve.

  • Page 127: Front Panel Curve Entry Operations

    5.7 Front Panel Curve Entry Operations 5.7 Front Panel There are four operations associated with front panel curve entry: Edit curve, View Curve, Erase Curve, and Copy Curve; as detailed below. Curve Entry Operations Operation Description Refer to section: Edit Curve allows you to edit curves at any user curve location. Stan- Edit Curve 5.7.1 dard curves cannot be changed.
  • Page 128 When curve entry is complete, you must assign the new curve to an input. The Model 72 does not automatically assign the new curve to any input. Refer to section 4.4.12 for details on assigning a curve to a sensor input. Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 129: View Curve

    Interface command: CRVDEL 5.7.4 Copy Curve Temperature curves can be copied from one location in the Model 372 to another. This is a good way to make small changes to an existing curve. Curve copy may also be necessary if you need the same curve with two different temperature limits or if you need to extend the range of a standard curve.

  • Page 130: Emulation Mode

    Model 370, the Model 372 can be configured to emulate the remote interface of the Mode Model 370. The emulation mode allows a Model 372 to replace a Model 370 in a soft- ware controlled system with very little effort, and very little downtime.

  • Page 131: Controlling While Scanning Differences

    370 provides a ±10 V voltage source output with 100 mA maximum current, provid- ing 1 W into a 100 ) heater. The Model 372 provides a +630 mA current source, pro- viding up to 10 W into a 25 ) or 50 ) load.
  • Page 132 X = 18.76 ) Series and parallel combinations can be used with standard resistor values to reach the desired equivalent resistance. Menu navigation: Interface Q Emulation Mode (None, Model 370) Interface command: EMUL Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 133: Chapter 6: Computer Interface Operation

    Cable lengths are limited to 2 m (6.6 ft) for each device and 20 m (66 ft) for the entire bus. The Model 372 can drive a bus with up to ten loads. If more instruments or cable length is required, a bus expander must be used.

  • Page 134: Changing Ieee-488 Interface Parameters

    LLO (Local Lockout): prevents the use of instrument front panel controls DCL (Device Clear): clears Model 372 interface activity and puts it into a bus idle state Finally, addressed bus control commands are multiline commands that must include the Model 372 listen address before the instrument responds.
  • Page 135 Most device specific com- mands also work if performed from the front panel. Model 372 device specific com- mands are detailed in section 6.6.1 and summarized in TABLE 6-6.

  • Page 136: Status System Overview

    6: Computer Interface Operation HAPTER 6.2.4 Status System The Model 372 implements a status system compliant with the IEEE-488.2 standard. The status system provides a method of recording and reporting instrument informa- Overview tion and is typically used to control the Service Request (SRQ) interrupt line. A dia- gram of the status system is shown in FIGURE 6-1.
  • Page 137 6.2.4 Status System Overview 6.2.4.3 Status Byte Register The status byte register, typically referred to as the status byte, is a non-latching, read-only register that contains all of the summary bits from the register sets. The status of the summary bits are controlled from the register sets as explained in sec- tion 6.2.4.1 to section 6.2.4.2.

  • Page 138: Status System Detail: Status Register Sets

    Power on instrument — TABLE 6-3 Register clear methods 6.2.5 Status System As shown in FIGURE 6-1, there is one register in the status system of the Model 372: the standard event status register. Detail: Status Register Sets 6.2.5.1 Standard Event Status Register Set...

  • Page 139: Status System Detail: Status Byte Register And Service Request

    6.2.6 Status System Detail: Status Byte Register and Service Request – Bit Standard event – Decimal Status register – Name *ESR? used used used (*ESR? reads and clears the register) To event summary Standard event – Bit bit (ESB) of status Status enable register byte register –...
  • Page 140 (section 6.2.6.4). The programming example in TABLE 6-4 initiates an SRQ when a command error is detected by the instrument. Model 372 AC Resistance Bridge and Temperature Controller...
  • Page 141 6.2.6 Status System Detail: Status Byte Register and Service Request Command or operation Description *ESR? Read and clear the standard event status register *ESE 32 Enable the Command Error (CME) bit in the standard event status register *SRE 32 Enable the Event Summary Bit (ESB) to set the RQS *ABC Send improper command to instrument to generate a command error Monitor bus...

  • Page 142: Usb Interface

    USB peripheral devices, and it allows the common USB A-type to Connection B-type cable to be used to connect the Model 372 to a host PC. The pin assignments for A-type and B-type connectors are shown in section 8.10. The maximum length of a USB cable, as defined by the USB 2.0 standard, is 5 m (16.4 ft).
  • Page 143 If the Found New Hardware wizard is unable to connect to Windows® Update or find the drivers, a message to “Insert the disc that came with your Lake Shore Model 372” will be displayed. Click Cancel and refer to section 6.3.3.3 to install the driver from the web.
  • Page 144 Lake Shore Model 372 should appear indented underneath Other Devices. If it is not displayed as Lake Shore Model 372, it might be displayed as USB Device. If neither are displayed, click Action and then Scan for hardware changes, which may open the Found New Hardware wizard automatically.

  • Page 145: Communication

    + icon. Lake Shore Model 372 should appear indented underneath Ports (COM & LPT). If it is not displayed as Lake Shore Model 372, it might be displayed as USB Device. If neither are displayed, click Action and then select Scan for hardware changes, which may open the Found New Hardware wizard automatically.

  • Page 146: Message Flow Control

    The Ethernet interface of the Model 372 provides the ability to use TCP socket connections (section 6.4.3) to send commands and queries to the instru- ment using the common command set detailed in section 6.6. The Model 372 has an embedded web interface that provides status information and additional utilities (section 6.5).
  • Page 147 Ethernet devices and the Model 372. The IP version used by the Model 372 is IPv4. The IPv6 standard is not supported. All references to the IP protocol from this point forward will be referring to IPv4.
  • Page 148 To use Static-IP to manually config- ure the IP address, subnet mask, and gateway of the Model 372, set the DHCP and the Auto-IP parameters to Off. Refer to the paragraphs above for details on turning off DHCP and Auto-IP.
  • Page 149 A hostname can be assigned by a network administrator, or if the Model 372 is con- nected to a network with Dynamic DNS (DDNS) capability, a DNS entry is automati- cally created for it using the Preferred Hostname and Preferred Domain Name parameters and the assigned IP address.

  • Page 150: Viewing Ethernet Configuration

    Lake Shore web server, located within the internet domain “lakeshore.com.” If the Model 372 is connected to a network with Dynamic DNS (DDNS) capability, a DNS entry is automatically created using the Preferred Hostname and Preferred Domain Name parameters and the assigned IP address.
  • Page 151 Cable Unplugged: the Ethernet cable is either unplugged at one end, or has been damaged Module Error: the Model 372 has lost contact with the Ethernet module; this may indicate a damaged Ethernet module Acquiring Address: the Model 372 is attempting to configure the IP address param- eters using the enabled methods 6.4.2.2 MAC Address...

  • Page 152: Tcp Socket Communication

    Model 372 will fail. 6.4.4 Embedded Web The Model 372 provides a web interface via an embedded web server that runs on the instrument. Once the Model 372 is properly connected, and the IP parameters prop- Interface erly configured, the web interface can be opened using a web browser.
  • Page 153 6.4.4 Embedded Web Interface Home Page: provides a summary of information specific to the Model 372. FIGURE 6-4 Model 372 home page Ethernet Configuration Page: provides a means of reconfiguring the Ethernet config- uration parameters of the Model 372. FIGURE 6-5 Ethernet configuration page Ethernet Status Page: provides status and statistics related to the current Ethernet connection.

  • Page 154: Utilities

    TCP Socket access (section 6.4.3). The website username and password are available from the front panel menu, and there- fore can easily be obtained by anyone with access to the Model 372 front panel. Contact Us: provides information regarding how to contact representatives of Lake Shore Cryotronics, Inc.

  • Page 155: Embedded Curve Handler

    Model 372. The utility is also capable of reading curves from the Curve Handler™ Model 372 and writing them to a file for storage, or manipulation in a third party pro- gram. The Embedded Curve Handler™ supports standard Lake Shore temperature curve files in the “.340”...

  • Page 156: Ethernet Firmware Updater

    At this point the application should check to see if the firmware you are attempting to update to is newer than what is already installed on the Model 372. If it is, then the firmware should immediately begin uploading, and the progress of the firmware update operation should be displayed using the two progress bars in the application window.

  • Page 157: Instrument Configuration Backup Utility

    6.5.3 Instrument The instrument configuration backup utility provides the means to export the current configuration of the Model 372 to a file, or to import a saved configuration from a file Configuration Backup to the Model 372. The utility is useful in situations where the instrument is shared...

  • Page 158: Embedded Chart Recorder

    Model 372. A basic user interface is also provided for changing control parameters on the fly while acquiring data, allowing many basic experiments to be performed without ever having to write any custom software.
  • Page 159 6.5.4 Embedded Chart Recorder 6.5.4.2 Starting Data Acquisition Once the parameters in the configuration panel are set as desired, simply click Start to begin data acquisition. If you are logging data to a file, the Number of Data Points to Log parameter is used to determine how many data points to take before terminat- ing data acquisition.
  • Page 160 (i.e. 522 of 1000). Log File (5)—the file path of the file that is currently being used to log data. Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 161: Command Summary

    6.6 Command Summary 6.6 Command This section provides a listing of the interface commands. A summary of all the com- mands is provided in TABLE 6-6. All the commands are detailed in section 6.6.1, and Summary are presented in alphabetical order. Command name Brief description of command INCRV...
  • Page 162 6: Computer Interface Operation HAPTER Model 372 AC Resistance Bridge and Temperature Controller...
  • Page 163 6.6 Command Summary Command Function Page Command Function Page CLS Clear Interface Cmd INSET Input Channel Parameter Cmd ESE Event Status Enable Register Cmd INSET? Input Channel Parameter Query ESE? Event Status Enable Register Query INTSEL Interface Select Cmd ESR? Standard Event Status Register Query INSTSEL? Interface Select Query...

  • Page 164: Interface Commands

    Refer to section 6.2.5 for a list of event flags. Example To enable event flags 0, 4, and 7, send the command *ESE 145[term]. 145 is the sum of the bit weighting for each bit. Bit weighting Event name Total: Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 165: Ese? Event Status Enable Register Query

    6.6.1 Interface Commands ESE? Event Status Enable Register Query ESE?[term] Input Returned <bit weighting>[term] Format nnn (refer to section 6.2.5 for a list of event flags) ESR? Standard Event Status Register Query ESR?[term] Input Returned <bit weighting> Format Remarks The integer returned represents the sum of the bit weighting of the event flag bits in the Standard Event Status Register.

  • Page 166: Sre Service Request Enable Register Cmd

    Returned <status>[term] Format <status> 0 = no errors found, 1 = errors found Remarks The Model 372 reports status based on test done at power up. WAI Wait-to-Continue Command WAI[term] Input Remarks Causes the IEEE-488 interface to hold off until all pending operations have been com- pleted.

  • Page 167: Alarm Parameter Cmd

    Remarks Configures the alarm parameters for a channel. On a Model 370, the alarm had an independent units setting. The 372 uses preferred units, therefore, the data source/ units field is ignored, but maintained for backwards compatibility. Therefore, pass a zero into this field when sending the command.

  • Page 168: Alarmst? Alarm Status Query

    The 370 analog output 1 has been replaced with the warm-up heater. To maintain backward compatibility, the ANALOG command will also configure the warm-up heater. Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 169: Analog? Analog Output Parameter Query

    6.6.1 Interface Commands ANALOG? Analog Output Parameter Query ANALOG? <analog channel>[term] Input Format <analog channel> Specifies analog output channel: 1 or 2. Returned <polarity>,<mode>,<input/channel>,<source>,<high value>,<low value>,<manual value>[term] Format n,n,nn,n, ±nnn.nnnE±nn, ±nnn.nnnE±nn,±nnnnnn (refer to command for definition) AOUT? Analog Output Data Query AOUT? <output>[term] Input Format...

  • Page 170: Brigt? Display Brightness Query

    It is not recommended to use commas or semi-colons in curve names or serial numbers as these characters are used as delimiters for query responses. Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 171: Curve Header Query

    6.6.1 Interface Commands CRVHDR? Curve Header Query CRVHDR? <curve>[term] Input Format <curve> Valid entries: 1 to 59. Returned <name>,<SN>,<format>,<limit value>,<coefficient>[term] Format s[15],s[10],n,+nnn.nnn,n (refer to command for description) CRVPT Curve Data Point Command CRVPT <curve>,<index>,<units value>,<temp value>, Input (optional)<curvature value>[term] Format nn,nnn,+nnn.nnnE±nn,+nnn.nnnE±nn,+nnn.nnnE±nn <curve>...

  • Page 172: Dispfld Custom Mode Display Field Cmd

    Because of this, the DISPLAY command only accepted one parameter, the num- ber of locations to display. Therefore, if the Model 372 is in emulation mode and the DISPLAY command is sent, the display mode will be forced to custom mode and the...

  • Page 173: Display? Display Number Query

    0 = off, 1 = on Remarks The 370 emulation mode provide a means of using the Model 372 in place of a Model 370 in a software controlled system without updating the software. The emulation mode setting only affects remote operation; front panel operation of the Model 372 is not changed.

  • Page 174: Filter Filter Parameter Cmd

    Specifies which input to query: 0 (measurement input), A (control input) Returned <frequency>[term] Format n (refer to command for description) Remarks If <input> is not specified, 0 (measurement input) is assumed for backwards compatibility. Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 175: Htr? Heater Output Query

    6.6.1 Interface Commands HTR? Heater Output Query HTR?[term] Input Returned <heater value>[term] Format ±nn.nnn <heater value> Sample heater output in percent (%) of current or in actual power depending on the heater output selection. Remarks HTR? applies only to the sample heater. Use AOUT? for the warm-up heater and the analog/still output.

  • Page 176: Ieee Ieee-488 Interface Parameter Cmd

    The terminator and EOI enabled fields are maintained for backwards compatibility with the Model 370. The Model 372 does not allow for configuration of these fields. Command strings must be terminated with a line feed or using the EOI line.

  • Page 177: Inname Sensor Input Name Command

    6.6.1 Interface Commands INNAME Sensor Input Name Command INNAME <input/channel>,<name>[term] Input Format n,s[15] <input/channel> Specifies which input or channel to configure: A (control input), 1 to 16 (measurement input) <name> Specifies the name to associate with the sensor input. Example INNAME 1,“Sample Space”[term] —...

  • Page 178: Intsel Interface Select Cmd

    14: 3.16 µA 15: 10.0 µA 16: 31.6 µA 17: 100 µA 18: 316 µA 19: 1.00 mA 20: 3.16 mA 21: 10.0 mA 22: 31.6 mA *Ranges not available with the 3708 scanner Model 372 AC Resistance Bridge and Temperature Controller...
  • Page 179 6.6.1 Interface Commands Control input current and implied resistance range number: Range Current Resistance 316 pA 632 k) 1 nA 200 k) 3.16 nA 63.2 k) 10 nA 20 k) 31.6 nA 6.32 k) 100 nA 2 k) <autorange> 0 = Autorange off, 1 = Autorange Current, 2 = ROX 102B Autor- ange (only available for control input) <range>...

  • Page 180: Intype? Input Setup Query

    Example LOCK 1,123[term]—enables keypad lock and sets the code to 123. LOCK? Keypad Lock Query LOCK?[term] Input Returned <state>,<code>[term] Format n,nnn (refer to command for description) Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 181: Mdat? Minimum/Maximum Data Query

    IEEE Interface Mode Command MODE <mode>[term] Input Format <mode> 0 = local, 1 = remote, 2 = remote with local lockout. Example MODE 2[term]—places the Model 372 into remote mode with local lockout. MODE? IEEE Interface Mode Query MODE?[term] Input Returned <mode>[term]...

  • Page 182: Mout Manual Heater Output Cmd

    NET? Network Settings Query NET?[term] Input Returned <DHCP>,<AUTO IP>,<IP>,<Sub Mask>,<Gateway>,<Pri DNS>,<Sec DNS>,<Pref Host>,<Pref Domain>,<Description>[term] Format n,n,dd,dd,dd,dd,dd,s[15],s[64],s[32] (refer to command for description) Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 183: Netid? Network Configuration Query

    6.6.1 Interface Commands NETID? Network Configuration Query NETID?[term] Input Returned <lan status>,<IP>,<sub mask>,<gateway>,<pri DNS>,<sec DNS>,<mac addr>,<actual host- name>,<actual domain>[term] Format n,dd,dd,dd,dd,dd,hh:hh:hh:hh:hh:hh,s[15],s[32] <lan status> Current status of Ethernet connection: 0 = Connected Using Static IP, 1 = Connected Using DHCP, 2 = Connected Using Auto IP, 3 = Address Not Acquired Error, 4 = Duplicate Initial IP Address Error, 5 = Duplicate Ongoing IP Address Error, 6 = Cable Unplugged, 7 = Module Error, 8 = Acquiring...

  • Page 184: Outmode? Output Mode Query

    Specifies which measurement input channel to query: 1 to 16 Returned <Quadrature value>[term] Format ±nnn.nnnE±nn Remarks The quadrature reading is only available on the measurement input. The value returned is the reactive (imaginary) reading in ohms for the given channel. Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 185: Ramp Setpoint Ramp Parameter Cmd

    6.6.1 Interface Commands RAMP Setpoint Ramp Parameter Command RAMP <output>,<off/on>,<rate value>[term] Input Format n,n,+nnnnn <output> 0 = sample heater, 1 = output 1 (warm-up heater). <off/on> Specifies whether ramping is on or off: 0 = off or 1 = on. <rate value>...

  • Page 186: Rdgk? Kelvin Reading Query

    Bit Weighting Status Indicator CS OVL VCM OVL VMIX OVL VDIF OVL R. OVER R. UNDER T. OVER T. UNDER Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 187: Rdgstl? Reading Settle Status Query

    6.6.1 Interface Commands RDGSTL? Reading Settle Status Query FILTERST? [term] Input Returned <Control input status>,<Active Measurement input Channel Status>[term] Format <status> 0 = Valid, 1 = Firmware Filter Settling, 2 = Hardware Settling RELAY Relay Parameter Command RELAY <relay number>,<mode>,<channel alarm>,<alarm Input type>[term] Format...

  • Page 188: Setp Temperature Control Setpoint Cmd

    <limit> The temperature limit in kelvin for which to shut down all control outputs when exceeded. A temperature limit of zero turns the temperature limit feature off for the given sensor input. Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 189: Tlimit? Temperature Limit Query

    WEBLOG? Website Login Parameter Query WEBLOG?[term] Input Returned <username>,<password>[term] Format s[15],s[15] (refer to command for description) Remarks Note that all strings returned by the Model 372 will be padded with spaces to main- tain a constant number of characters. www.lakeshore.com...

  • Page 190: Zone Control Loop Zone Table Parameter Cmd

    Specifies which zone in the table to query. Valid entries: 1 to 10. Returned <upper bound>, <P value>, <I value>, <D value>, <mout value>, <range>, <rate>, <relay 1>, <relay 2> [term] Format +nnn.nnnE±nn,+nnnnnn,+nnnnnn,+nnnnnn,±nnnnnn,n,±nnnnnn,n,n (refer to command for description.) Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 191: Chapter 7: Options And Accessories

    AC Resistance Bridge with Scanner. Includes a Lake Shore Model 372 AC Resistance Bridge with 372S a Lake Shore Model 3726 16 channel scanner and 3 m (10 ft) cable. Power is configured as shown inTABLE 7-3. AC Resistance Bridge with Scanner. Includes a Lake Shore Model 372 AC Resistance Bridge with 372S-6 a Lake Shore Model 3726 16 channel scanner and 6 m (20 ft) cable.

  • Page 192: Accessories

    Scanner box mounting bracket; used to mount the 3726 and 3708 †‡ G-112-374 † Cable assembly; connects the Model 372 to the optional scanner, 3 m (10 ft) long; FIGURE 7-1 G-112-375 † Cable assembly; connects the Model 372 to the optional scanner, 6 m (20 ft) long; FIGURE 7-1 G-112-376 †...
  • Page 193 7.3 Accessories FIGURE 7-1 Cable assembly to connect Model 372 to optional scanner Female Male DB15 DB15 Shield not To scanner To Model 372 attached FIGURE 7-2 Scan control www.lakeshore.com...

  • Page 194: Rack Mounting

    HAPTER 7.4 Rack Mounting The Model 372 can be installed into a 483 mm (19 in) rack mount cabinet using the optional Lake Shore Model RM-1 Rack Mount Kit. The kit contains mounting ears, handles and screws that adapt the front of the instrument to fit into a 89 mm (3.5 in) tall, full rack space.

  • Page 195: Chapter 8: Service

    Lockups ment is not being overloaded. 3. Ensure that the USB cable is not unplugged and that the Model 372 is not pow- ered down while the com port is open. The USB driver creates a com port when the USB connection is detected, and removes the com port when the USB connec- tion is no longer detected.

  • Page 196: Ieee Interface Troubleshooting

    8.4 Fuse Drawer The fuse drawer supplied with the Model 372 holds the instrument line fuses and line voltage selection module. The drawer holds two 5 mm × 20 mm (0.2 in × 0.79 in) time delay fuses.

  • Page 197: Fuse Replacement

    8.6 Fuse Replacement FIGURE 8-2 Power fuse access 8.6 Fuse Use this procedure to remove and replace a line fuse. Replacement To avoid potentially lethal shocks, turn off controller and disconnect it from AC power before performing these procedures. For continued protection against fire hazard, replace only with the same fuse type and rating specified for the line voltage selected.
  • Page 198 Measurement input frequency 13.7 Hz Displayed output Sample heater Control input frequency 16.2 Hz Interface setup – general Default Common mode reduction Enabled Monitor output Baud 57,600 Emulation mode None TABLE 8-1 Default values Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 199: Product Information

    The calibration memory is either corrupt, or is at the default, uncalibrated state. This *** Invalid Calibration *** message appears when the Model 372 is first powered on. To clear the message, and continue with instrument start-up, press the Escape and Enter keys simultaneously.

  • Page 200: Rear Panel Connector Definition

    Not used None Not used TABLE 8-3 Measurement input connector details FIGURE 8-4 Control input Symbol Description I– –Current V– –Voltage None Shield +Voltage +Current None Shield TABLE 8-4 Control input connector details Model 372 AC Resistance Bridge and Temperature Controller...
  • Page 201 8.10 Rear Panel Connector Definition FIGURE 8-5 Heater terminal block for relays and Output 3 and 4 Description Sample heater + Sample heater – Analog out (still heater) + Analog out (still heater) – Not used (floating) Warm-up heater + Warm-up heater –...
  • Page 202 FIGURE 8-7 USB pin and connector details Name Description +5 VDC Data – Data + Ground TABLE 8-7 USB pin and connector details FIGURE 8-8 Ethernet pin and connector details Model 372 AC Resistance Bridge and Temperature Controller...

  • Page 203: Ieee-488 Interface Connector

    The total length of cable allowed in a system is 2 m (6.6 ft) for each device on the bus, or 20 m maximum. The Model 372 can drive a bus of up to 10 devices. A connector extender is required to use the IEEE-488 interface and relay terminal block at the same time.

  • Page 204: Scan Control

    The scan control is shown in FIGURE 8-10 and defined in TABLE 8-10. FIGURE 8-10 Scan control Name Description Scan present Signal to Model 372 that a scanner is installed Digital common Common or ground for digital control signals Digital common Unused —...

  • Page 205: Firmware Updates

    Two new excitation frequencies (11.6 Hz and 18.2 Hz) for both inputs TABLE 8-11 Model 372 firmware releases 8.12 Analog Signal It is likely through the course of installation and usage that the Model 372 will meet conditions that cannot yield a valid resistance reading. These conditions can usually Troubleshooting be traced to environmental noise or misapplied measurement parameters.
  • Page 206 (section 3.5.5). Next, verify the integrity of the measurement lead shields. Use of the Common Mode Reduction (CMR) feature of the Model 372 reduces this effect electronically. It is particularly effective at excitation currents above 1 µA.
  • Page 207 8.12.1 Overload Monitoring 8.12.1.4 VMIX OVL (Mixer Overload — Measurement Input Only) Between the instrumentation amplifier section and the ADC sampling and lock-in portion of the DSP phase sensitive detector are several gain stages. If the combination of signal and all differential noise components cause the input to the ADC to exceed 10 V peak, the DSP detects this and informs the main microprocessor to display mixer overload error.

  • Page 208: Signal Level Troubleshooting

    8: Service HAPTER 8.12.2 Signal Level The Model 372 provides user access to all the error monitoring points in the circuit for Troubleshooting troubleshooting convenience. Access to these points is provided through the diagnostic monitor output BNC connector on the back of the instrument. To select the desired monitoring point, refer to section 4.7.4 (Monitor Output Voltages).
  • Page 209 The normal signal level is very small at these points and may not be easily observed when measuring at low excitations. Although the Model 372 largely ignores common-mode noise, there may be a large enough signal to cause a problem. If a “VCM OVL”...
  • Page 210 “R. UNDER” message. 8.12.2.3 Phase Relationship The design of the Model 372 includes a phase sensitive detector algorithm imple- mented inside the DSP that uses a reference signal directly derived from its oscillator to demodulate the voltage signal from the measured resistor. The reference signal is brought out to the back of the instrument next to the monitor jack.

  • Page 211: Summary Of Internal Memory Devices

    8.13 Summary of Internal Memory Devices 8.13 Summary of This section outlines the internal memory devices used inside the Model 372 AC resis- tance bridge and temperature controller, and provides an explanation of the types of Internal Memory data they contain.

  • Page 212: Technical Inquiries

    Questions regarding product applications, price, availability and Inquiries shipments should be directed to sales. Questions regarding instrument calibration or repair should be directed to instrument service. Do not return a product to Lake Shore without a Return Material Authorization (RMA) number (section 8.14.2). 8.14.1 Contacting The Lake Shore Service Department is staffed Monday through Friday between the hours of 8:00 AM and 5:00 PM EST, excluding holidays and company shut down days.

  • Page 213: Shipping Charges

    8.14.4 Shipping Charges 8.14.4 Shipping All shipments to Lake Shore are to be made prepaid by the customer. Equipment serviced under warranty will be returned prepaid by Lake Shore. Equipment serviced Charges out-of-warranty will be returned FOB Lake Shore. 8.14.5 Restocking Fee Lake Shore reserves the right to charge a restocking fee for items returned for exchange or reimbursement.
  • Page 214 8: Service HAPTER Model 372 AC Resistance Bridge and Temperature Controller...

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