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Ametek 7124 Instruction Manual

Precision lock-in amplifier
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Model 7124
Precision
Lock-in Amplifier
Instruction Manual
197776-A-MNL-F
Copyright © 2017 AMETEK ADVANCED MEASUREMENT TECHNOLOGY, INC

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Summary of Contents for Ametek 7124

  • Page 1 Model 7124 Precision Lock-in Amplifier Instruction Manual 197776-A-MNL-F Copyright © 2017 AMETEK ADVANCED MEASUREMENT TECHNOLOGY, INC...
  • Page 2 Firmware Version The instructions in this manual apply to operation of a Model 7124 Precision Lock-in Amplifier that is fitted with Version 2.20 or later operating firmware. Users of instruments that are fitted with earlier firmware versions can update them to the current version free of charge by downloading an Update Pack from our website at www.signalrecovery.com The pack includes full instructions for use.

  • Page 3: Table Of Contents

    3.2.06 Virtual Reference Mode .......................... 3-2 3.3 Principles of Operation ............................. 3-2 3.3.01 Block Diagram ............................3-2 3.3.02 Signal Channel Inputs - 7124 RCU ......................3-4 3.3.03 Line Frequency Rejection Filter ......................3-5 3.3.04 AC Gain and Dynamic Reserve....................... 3-5 3.3.05 Anti-Aliasing Filter ..........................
  • Page 4 4.2.12 TTL REF IN Connector ...........................4-7 4.2.13 TRIG IN Connector ..........................4-8 4.2.14 TRIG OUT Connector ..........................4-8 4.2.15 DAC 1, DAC 2, DAC 3, and DAC 2 Connectors ..................4-8 4.2.16 FIBER LINKS Connectors ........................4-8 4.3 Front Panel - 7124 RCU ............................4-8...
  • Page 5 4.3.02 REF IN Connector ........................... 4-9 4.3.03 OSC OUT Connector ..........................4-9 4.3.04 STATUS LED ............................4-9 4.4 Rear Panel - 7124 RCU ............................ 4-9 4.4.01 Line Power Switch ..........................4-9 4.4.02 Line Power Input Assembly ........................4-9 4.4.03 DIGITAL OUTPUT Connector....................... 4-9 4.4.04 TTL REF IN Connector.........................
  • Page 6 TABLE OF CONTENTS 5.3.33 Digital Port Menu ...........................5-55 5.3.34 RCU Digital Port Menu..........................5-56 5.3.35 Fiber Calibration Menu ..........................5-56 5.4 Menu Descriptions - Virtual Reference Mode ....................5-57 5.4.01 Virtual Reference Menus ........................5-57 5.4.02 Virtual Reference Main Display ......................5-60 5.4.03 Virtual Reference Configuration Menu ....................5-61 5.5 Menu Descriptions - Dual Reference Mode ....................5-61 5.5.01 Dual Reference Setup Menu ........................5-61 5.5.02 Dual Reference Main Display ........................5-62...
  • Page 7 TABLE OF CONTENTS 6.4 USB Operation ..............................6-5 6.4.01 Introduction ............................. 6-5 6.4.02 General Features ............................6-5 6.4.03 Terminator, Status Byte, and Overload Byte ..................6-5 6.4.04 Delimiters ..............................6-6 6.5 Ethernet Operation ............................6-7 6.5.01 Introduction ............................. 6-7 6.5.02 IP Address ............................... 6-7 6.5.03 Home Page ...............................
  • Page 8 TABLE OF CONTENTS Appendix E, 7124/99 DC Power Option for 7124 RCU E.1 Introduction ............................... E1 E.2 7124 RCU POWER Connector ......................... E1 E.3 7124/99 DC Power Input Cable ........................E1 E.4 Operation ................................E2 E.5 DC Power Over- and Under- Voltage Protection ..................... E2 E.6 Line Power/DC Input Power Switching ......................

  • Page 9: General Safety Precautions

    TABLE OF CONTENTS GENERAL SAFETY PRECAUTIONS The equipment described in this manual has been designed in accordance with EN61010 "Safety requirements for electrical equipment for measurement, control and laboratory use", and has been supplied in a safe condition. To avoid injury to an operator or service technician the safety precautions given below, and throughout the manual, must be strictly adhered to, whenever the equipment is operated, serviced or repaired.
  • Page 10 TABLE OF CONTENTS Avoid Unsafe Equipment The equipment may be unsafe if any of the following statements apply:  Equipment shows visible damage.  Equipment has failed to perform an intended operation.  Equipment has been stored in unfavorable conditions. ...
  • Page 11 89/336/EEC Electromagnetic Compatibility Directive, amended by 92/31/EEC & 93/68/EEC Product(s) Model 7124 Precision Lock-in Amplifier Basis on which conformity is being declared The product(s) identified above comply with the requirements of the EU directives by meeting the following standards: BS EN61326:1998 Electrical equipment for measurement control and laboratory use - EMC requirements;...
  • Page 12 TABLE OF CONTENTS...

  • Page 13: Chapter One, Introduction

    Appendix D Provides a listing of the instrument settings produced by using the Auto-Default functions. Appendix E Describes how to use the 7124/99 option that allows the 7124 RCU unit to be powered from external DC power supplied (e.g. batteries).

  • Page 14: What Is A Lock-In Amplifier

    (the 7124 RCU), to which the experiment is connected, and a main instrument console. In normal operation there are no digital clock signals within the 7124 RCU, and so it can emit no switching noise.

  • Page 15: Key Specifications And Benefits

    1.3 Key Specifications and Benefits In addition to its unique fiber optic link to isolate the experiment from digital switching noise, the SIGNAL RECOVERY Model 7124 represents a further significant advance in the application of DSP technology in the design of a lock-in amplifier.
  • Page 16 Chapter 1, INTRODUCTION  Standard USB, Ethernet, and RS232 interfaces with RS232 daisy-chain capability for up to 16 instruments.  Large high-resolution color LCD display panel with menus for control and display of instrument outputs in both digital and graphical formats ...

  • Page 17: Installation

    2" (5 cm) between these panels and any adjacent surface. The 7124 RCU does not use cooling fans and therefore simply needs to be located so that there is a free flow of air around the unit.
  • Page 18 Position the barrel selector such that the required number (see table 2-1) will be visible when the barrel selector is inserted and the door closed. Figure 2-1, Line Input Assemblies (Left - Main Console; Right - 7124 RCU) VISIBLE #...

  • Page 19: Initial Checks

    SIGNAL RECOVERY or the nearest authorized representative for assistance. 2.2.02 Procedure 1) Ensure that both the 7124 main console and the 7124 RCU are set to the line voltage of the power source to be used, as described in section 2.1.05.
  • Page 20 Such contamination is not covered under the instrument warranty. Retain the connector covers from the 7124 main console and the 7124 RCU for use when needed. 10) With both rear-panel mounted power switches set to 0 (off), plug in the line cords to an appropriate line power source.
  • Page 21 Chapter 2, INSTALLATION AND INITIAL CHECKS Figure 2-3, Main Menu 1 15) Press one of the keys adjacent to the Auto functions menu item to enter the Auto Functions menu, shown below in figure 2-4. Figure 2-4, Auto Functions Menu 16) Press one of the keys adjacent to the Auto Default menu item.
  • Page 22 Figure 2-5, Main Display 17) Connect a BNC cable between the OSC OUT and A input connectors on the front panel of the 7124 RCU. 18) Press the Menu key to return to Main Menu 1 and then press one of the keys adjacent to the Main menu 2 item to enter Main Menu 2, shown below in figure 2-6.

  • Page 23: Line Frequency Filter Adjustment

    2.3.02 Procedure 1) Turn the model 7124 RCU power switch to the I (on) position. 2) Turn the 7124 main console power switch to the I (on) position. 3) The instrument's front panel display will now briefly display the following:-...
  • Page 24 Chapter 2, INSTALLATION AND INITIAL CHECKS Figure 2-6, Opening Display 4) Wait until the opening display has changed to the Main Display and then press the key under the bottom right hand corner of the display identified by the legend MENU on the display once.
  • Page 25 Chapter 2, INSTALLATION AND INITIAL CHECKS Figure 2-8, Configuration Menu 5) Press one of the keys adjacent to the Configuration menu item to enter the Configuration Menu 2, shown below in figure 2-9. Figure 2-9, Configuration Menu 2 6) The present line frequency setting is shown under the LINE FREQUENCY label and is either 50 or 60 Hz.
  • Page 26 Chapter 2, INSTALLATION AND INITIAL CHECKS 2-10...

  • Page 27: Introduction

    3.2.02 Single Reference / Dual Reference Conventionally, a lock-in amplifier makes measurements such as signal magnitude, phase, etc. on the applied signal at a single reference frequency. In the model 7124 this is referred to as the single reference mode.

  • Page 28: Single Harmonic / Dual Harmonic

    The model 7124 allows this multiple to be set to any value between 2 (i.e. the second harmonic) and 127, as well as unity, which is the normal mode.
  • Page 29 Main Console are shown in figures3-1 and 3-2, and the sections that follow describe how each functional block operates and the effect it has on the instrument's performance. Figure 3-1, Model 7124 RCU - Block Diagram Figure 3-2, Model 7124 Main Console - Block Diagram...

  • Page 30: Signal Channel Inputs - 7124 Rcu

    Chapter 3, TECHNICAL DESCRIPTION 3.3.02 Signal Channel Inputs - 7124 RCU The signal input amplifier can be set for either single-ended or differential voltage mode operation, or single-ended current mode operation. In voltage mode a choice of AC or DC coupling is available using an FET input device. In current mode a choice of two conversion gains is available to give optimum matching to the applied signal.

  • Page 31: Line Frequency Rejection Filter

    Chapter 3, TECHNICAL DESCRIPTION 3.3.03 Line Frequency Rejection Filter Following the signal input amplifier there is an option to pass the signal through a line frequency rejection filter, which is designed to give greater than 40 dB of attenuation at the power line frequencies of 50 Hz or 60 Hz and their second harmonics at 100 Hz and 120 Hz.

  • Page 32: Anti-Aliasing Filter

    For the benefit of users who prefer to have the AC Gain value expressed in decibels, the model 7124 displays the current value of Dynamic Reserve (DR) in this form, on the input full-scale sensitivity control, for values up to 100 dB. Above 100 dB the legend changes to “DR>100”.

  • Page 33: Analog Fiber Links

    A buffered version of the analog signal just prior to transmission via the fiber link is available at the signal monitor (SIG MON) connector on the rear panel of the 7124 RCU; it may be viewed on an oscilloscope to monitor the effect of the line frequency rejection and anti-aliasing filters and signal-channel amplifiers.

  • Page 34: Main Analog-To-Digital Converter

    3.3.09 Reference Channel Inputs - 7124 RCU The 7124 RCU provides two signal inputs for an external reference signal. The front panel REF IN is a general-purpose input, designed to accept virtually any periodic waveform with a 50:50 mark-space ratio and of suitable amplitude, while the rear- panel TTL REF IN is suitable for TTL-logic level input signals.

  • Page 35: Phase-Shifter

    Chapter 3, TECHNICAL DESCRIPTION external references. External Reference Mode In external reference mode the reference is taken from one of the four possible external reference inputs, two on the RCU and two on the main console. Internal Reference Mode With internal reference operation the reference circuit is free-running at the selected reference frequency and is not dependent on a phase-locked loop (PLL), as is the case in most other lock-in amplifiers.

  • Page 36: Internal Oscillator - General

    When virtual reference mode is in use, the signal at the OSC OUT connector (on the main console or the 7124 RCU) is a sinusoid which is phase-locked to the signal. 3-10...

  • Page 37: Internal Oscillator - Voltage Control

    12 dB per octave. These terms have become part of the accepted terminology relating to lock-in amplifier output filters and are used in the model 7124 to apply to the envelope of the frequency response function of the digital finite impulse response (FIR) output filters. Accordingly the front-panel control which selects the configuration of the output filters is labeled SLOPE and the options are labeled 6, 12, 18, 24 dB/octave.

  • Page 38: Fast Curve Buffer

    1 reference cycle. 3.3.19 Fast Curve Buffer The fast curve buffer is a new feature in the 7124 lock-in amplifier when compared to other SIGNAL RECOVERY instruments. It allows up to 100,000 sets of eight signals to be recorded at rates of up to 1 MSa/s (1 µs per point), and supports a variety of trigger modes.

  • Page 39: Main Output Processor - Vector Magnitude And Phase

    Chapter 3, TECHNICAL DESCRIPTION 3.3.22 Main Output Processor - Vector Magnitude and Phase The processor also implements the magnitude and signal phase calculation, which is useful in many situations. If the input signal V (t) is a reference frequency sinusoid of constant amplitude, and the output filters are set to a sufficiently long time constant, the X and Y channel demodulator outputs are constant levels.

  • Page 40: Main Output Processor - Noise Measurements

    Chapter 3, TECHNICAL DESCRIPTION X-Y mode, with the phase-shifter adjusted to maximize the X output and to bring the mean Y output to zero. (Refer to section 3.3.29 for further information on the correct use of the Auto-Phase function for this purpose.) 3.3.23 Main Output Processor - Noise Measurements The noise measurement facility uses the output processor to perform a noise computation on the X output of the demodulator.

  • Page 41: Main Output Processor - Standard Curve Buffer

    This design has been updated and so the 7124 main console is fitted with four general-purpose DAC outputs, which can be driven from a variety of output signals, as well as the traditional programmable “auxiliary DAC”...

  • Page 42: Main Microprocessor - General

    In some cases it can be useful to determine the spectral power distribution of the input signal. The model 7124 can do this, since when the Spectral Display menu is selected, the output processor performs a discrete Fourier transform on the digitized input signal and displays the resulting spectrum.
  • Page 43 Chapter 3, TECHNICAL DESCRIPTION channel while maximizing the output of the X channel. Any small residual phase can normally be removed by calling Auto-Phase for a second time, after a suitable delay to allow the outputs to settle. The Auto-Phase facility is normally used with a clean signal that is known to be of stable phase.

  • Page 44: Main Microprocessor - User Settings

    Auto-Sensitivity followed by Auto-Phase functions. Auto-Default With an instrument of the design of the model 7124, where there are many controls of which only a few are regularly adjusted, it is very easy to overlook the setting of one of them.

  • Page 45: Front Panel - Main Console

    4.1.02 MON Connector The signal at this connector is that immediately prior to the main analog-to-digital converter, as received from the 7124 RCU via the fiber optic link or the AUX signal input connector. 4.1.03 REF IN Connector This is the general-purpose input connector for an external reference signal when this is applied at the main console as opposed to the 7124 RCU.

  • Page 46: Osc Out Connector

    The model 7124 is a very sophisticated instrument with many features and consequently had the traditional approach of using one button per control been adopted the front panel would have been very large.
  • Page 47 In some cases it is useful to be able to quickly adjust a control in equal increments, for example when monitoring the effect of changing the oscillator frequency about a given value. This is easily done in the model 7124 using a control setting feature known as Active Cursor operation.
  • Page 48 Chapter 4, FRONT AND REAR PANELS Step 3 Press the key to change the digit to the required value. Figure 4-3, Active Cursor Activation As an example of this operation, suppose that the oscillator frequency is 1000.000 Hz and it is required to change it to 1001.000 Hz. Simultaneously press both keys adjacent to the oscillator frequency display.

  • Page 49: Help Key

    To exit the help system and return to normal operation press the EXIT HELP key. 4.1.07 MENU Key The model 7124 is controlled by a series of on-screen menus. When the Main Display is shown the MENU key is used to access Main Menu 1, from which other menus may be accessed.

  • Page 50: Rear Panel - Main Console

    4.2.01 Line Power Switch CAUTION: The model 7124 may be damaged if the line voltage is set for 110 V AC operation and it is turned on with 220 V AC applied to the power input connector.

  • Page 51: Lan Connector

    Chapter 4, FRONT AND REAR PANELS a Windows operating system via the USB bus. The instrument supports connection at both Full Speed and Hi-Speed (USB 2.0) protocols. 4.2.05 LAN Connector This connector allows the instrument to be connected to a 100-BaseT or 10-BaseT network for remote control.

  • Page 52: Trig In Connector

    4.3 Front Panel - 7124 RCU Figure 4-6, Model 7124 RCU Front Panel Layout As shown in figure 4-6, the model 7124 RCU has four BNC connectors and an LED on its front panel. The following sections describe the function and location of these items.

  • Page 53: Ref In Connector

    This is the output connector for the internal oscillator when this signal is to be output at the 7124 RCU. Note that this output must be set active using the Oscillator Menu on the main console in order to work.

  • Page 54: Ttl Ref In Connector

    4.4.05 POWER IN/OUT Connector When the 7124 RCU is line powered, this connector supplies ±15 V at up to 100 mA and can be used for powering optional remote preamplifiers available from SIGNAL RECOVERY. When the model 7124/99 option is fitted, it is used to connect external DC ±24 V power supplies.

  • Page 55: Introduction

    Chapter 5.1 Introduction This chapter describes how to operate the model 7124 using the front panel controls, and discusses its capabilities when used in this way. Chapter 6 provides similar information for when the unit is operated remotely using one of the computer interfaces.

  • Page 56: Menu Structure

    Chapter 5, FRONT PANEL OPERATION channel output from the first, allows the 7124 to make this measurement in a single instrument. Dual Harmonic Dual harmonic mode allows the simultaneous measurement of two different harmonics of the input signal. The sections that follow describe the menus as they appear when the unit is being used in single reference mode.

  • Page 57: Menu Descriptions - Single Reference Mode

    Chapter 5, FRONT PANEL OPERATION followed by the Signal Channel key shown in Main Menu 1; to return to Main Menu 1 press the Previous Menu key on the Signal Channel menu. Note that all menus provide a Previous Menu key allowing the user to return one step up the menu "tree".
  • Page 58 Chapter 5, FRONT PANEL OPERATION Output Description Numeric Displays only: Resultant (Magnitude) output as a percentage of full-scale sensitivity Noise output as a percentage of full-scale sensitivity ° Phase output in degrees X channel output as a percentage of full-scale sensitivity Y channel output as a percentage of full-scale sensitivity Resultant (Magnitude) output in volts or amps Numeric and Bar-Graph Displays:...

  • Page 59: Control Selection Menu

    Chapter 5, FRONT PANEL OPERATION Gain. To obtain the best accuracy, use the highest value of AC Gain that is possible without causing signal input overload, indicated by the words Input Overload in the top left-hand corner of the screen flashing on and off. The Input Limit value, displayed immediately under the AC Gain control, is the largest value of rms signal that may be applied without causing signal overload.
  • Page 60 2.000 kHz. RELOCK EXT. REFERENCE The 7124 includes frequency-dependent calibration parameters. When operating in Internal reference mode the correct parameters can be chosen because the reference frequency is equal to the specified oscillator frequency. In External reference mode the applied frequency is measured, and the measured value is used to select the correct parameters.

  • Page 61: Signal Channel Menu 1

    Keypad or Active Cursor controls - see section 4.1.04. RCU OSC AMPLITUDE This control sets the amplitude of the signal at the 7124 RCU’s OSC OUT connector to any value between 1 mV and 5 V rms. Adjustment is faster using the Keypad or Active Cursor controls - see section 4.1.04.
  • Page 62 The Signal Channel Menu 1 has four controls affecting the instrument's signal input channel at the 7124 RCU console, and a key for accessing Signal Channel Menu 2. Changes to the setting of these controls can be made by using the adjacent keys, with the currently active selection being shown in highlighted text.
  • Page 63 The shells of the A and B/I connectors at the 7124 RCU are connected directly to chassis ground. FLOAT The shells of the A and B/I connectors at the 7124 RCU are connected to chassis ground via a 1 k resistor. INPUT MODE This control sets the preamplifier input configuration to either voltage or current mode, and also changes the function of the INPUT CONNECTOR control.
  • Page 64 INPUT DEVICE This control selects the type of input device used for the signal channel connections at the 7124 RCU FET (FET input device) Uses a FET as the input device, for which case the input impedance is 10 M.

  • Page 65: Reference Channel Menu

    (at the 7124 RCU or the AUX input on the main console) and share a common path through the main ADC.
  • Page 66 7124 RCU front panel REF IN input connector EXTr In this setting the reference channel is configured to accept a suitable external reference source applied to the 7124 main console rear panel TTL REF IN input connector EXTf...

  • Page 67: Output Filters Menu

    Chapter 5, FRONT PANEL OPERATION 5.3.06 Output Filters Menu When Main Menu 1 is displayed, pressing a key adjacent to the Output Filters item accesses the Output Filters menu, which is shown in figure 5-9. Figure 5-9, Output Filters Menu The Output Filters menu has four controls affecting the instrument's main X and Y channel output filters.

  • Page 68: Output Offset & Expand Menu

    Chapter 5, FRONT PANEL OPERATION settings are available. FAST In this setting, the analog outputs are derived directly from the core FPGA running the demodulator algorithms. The update rate is increased to 1.0 MHz when the time constant is set to any value from 10 µs to 500 ms but remains at 1 kHz for longer time constants.

  • Page 69: Output Equations Menu

    Chapter 5, FRONT PANEL OPERATION The X channel output offset is switched on. The Y channel output offset is switched on. X&Y Both X channel and Y channel output offsets are switched on. OUTPUT EXPAND This control allows a ×10 output expansion to be applied to the X, Y or both output channels, or to be switched off:- NONE Output expansion is turned off.

  • Page 70: Oscillator Menu

    Chapter 5, FRONT PANEL OPERATION where the operator "±" may be set to either addition or subtraction, and the variables A, B, C and D can be chosen from the following list:- Variable Range ±30000 ±30000 0 to +30000 PHA (Phase) ±18000 ADC1 ±10000...
  • Page 71 Chapter 5, FRONT PANEL OPERATION Figure 5-12, Oscillator Menu The Oscillator menu has five controls affecting the instrument's internal oscillator, and is also used for accessing sub-menus that control oscillator frequency and amplitude sweeps, and frequency and amplitude modulation. The relationship of these menus to Main Menu 1 is shown in figure 5-13.

  • Page 72: Frequency Sweep Menu

    RCU OSCILLATOR This control selects whether the calibrated internal oscillator output signal will appear at the 7124 main console or the 7124 RCU OSC OUT connector. it has two settings, as follows: The 7124 main console OSC OUT connector is active.
  • Page 73 Chapter 5, FRONT PANEL OPERATION Figure 5-14, Frequency Sweep Menu The Frequency Sweep menu has nine controls affecting the instrument's internal oscillator, and a link to the Curve Buffer menu (see section 5.3.24). Changes to the setting of the controls can be made by using the adjacent keys.
  • Page 74 Chapter 5, FRONT PANEL OPERATION see section 5.3.11, although the minimum time per point for such sweeps is 1 s when the RCU oscillator output is being used. ARMED When this control is set to YES, the frequency sweep is armed. The sweep can then be started in one of two ways: a) If the LINK TO CURVE BUFFER control is set to YES then the sweep will be started at the same time as a curve buffer acquisition starts (see section 5.3.24).

  • Page 75: Amplitude Sweep Menu

    Chapter 5, FRONT PANEL OPERATION 1000.000 Hz 1610.510 Hz 1100.000 Hz 1771.561 Hz 1210.000 Hz 1948.717 Hz 1331.000 Hz 2000.000 Hz 1464.100 Hz LINEAR Selects a linear relationship. Pressing the Curve Buffer key accesses the Curve Buffer menu, described in section 5.3.24, while pressing the Previous Menu key returns control to the Oscillator Menu.
  • Page 76 Chapter 5, FRONT PANEL OPERATION is faster using the Keypad or Active Cursor controls - see section 4.1.04. STEP AMPLITUDE This control defines the amount by which the oscillator amplitude is changed at each step. It may be set to any value between 0.000 V rms and 5.000V rms with a 1 mV resolution.

  • Page 77: Amplitude Modulation Menu

    Chapter 5, FRONT PANEL OPERATION Note that if the oscillator frequency sweep (see section 5.3.10) is also armed then the controls that start, pause, continue and stop on the Amplitude Sweep menu will also control the frequency sweep. Similarly, if the amplitude sweep is linked to the curve buffer then the frequency sweep will be as well.

  • Page 78: Frequency Modulation (Vco) Menu

    The control signal should be applied to the external reference channel (either TTL or analog inputs on either the main console or the 7124 RCU). Because the reference channel internally generates a fixed signal amplitude that is used as the control signal for the amplitude modulation, the CENTER VOLTAGE and VOLTAGE SPAN controls are inactive.

  • Page 79: Auto Functions Menu

    Chapter 5, FRONT PANEL OPERATION follows:- CENTER FREQUENCY This control may be set to any value between 0.5 Hz and 150.00 kHz. Adjustment is faster using the Keypad or Active Cursor controls - see section 4.1.04. FREQUENCY SPAN This control defines the maximum frequency span that will be applied to the oscillator signal.
  • Page 80 Chapter 5, FRONT PANEL OPERATION AUTO SENSITIVITY This function only operates when the reference frequency is above 1 Hz. A single Auto-Sensitivity operation consists of increasing the full-scale sensitivity range if the magnitude output is greater than 90% of full-scale, or reducing the range if the magnitude output is less than 30% of full-scale.

  • Page 81: Configuration Menu

    Offset function should be executed before any execution of Auto-Phase. AUTO DEFAULT With an instrument of the design of the model 7124, where there are many controls of which only a few are regularly adjusted, it is very easy to overlook the setting of one of them.
  • Page 82 Chapter 5, FRONT PANEL OPERATION Figure 5-19, Configuration Menu, Single Reference Mode The Configuration menu has four controls used to set the instrument’s basic operating mode and controls to adjust the noise measurement mode. Changes to the setting of these controls can be made by using the adjacent keys.

  • Page 83: Communications Menu

    Chapter 5, FRONT PANEL OPERATION turned ON, the Main Display output displays (see section 5.3.01) are set as follows: Display Position Displayed Output Noise expressed in V/Hz in large digits Noise expressed in V/Hz as a bar-graph X output in expressed as a percentage of the full-scale sensitivity as a bar-graph Magnitude output (R) output in expressed as a percentage of the full-scale sensitivity in large digits.

  • Page 84: Rs232 Settings Menu

    Chapter 5, FRONT PANEL OPERATION Figure 5-21, Communications Menu The Communications menu has keys to access four sub-menus. The elapsed time indicator in the bottom right hand corner reports the total time for which the instrument has been powered up. Pressing the Previous Menu key returns control to the Configuration Menu.
  • Page 85 ECHO This control, when switched on, causes the model 7124 to echo each character received over the RS232 interface back to the controlling computer. The computer should wait until the echoed character is returned before it sends the next character.

  • Page 86: Ethernet Settings Menu

    Chapter 5, FRONT PANEL OPERATION PARITY This control sets the parity check polarity when the Data Bits control specifies that a parity bit should be used. It should be set to match the setting of the controlling computer. Pressing the Previous Menu key returns control to the Configuration Menu, and pressing the Communications Monitor key accesses the Communications Monitor display.
  • Page 87 Chapter 5, FRONT PANEL OPERATION When the IP Address Assignment control is set to Automatic, they function simply as indicators showing the settings allocated by the DHCP server. Figure 5-24, IP Address Setup Menu Computer IP Address In normal use, the instrument will accept connections from any IP address, and hence can be operated from any computer on the network.

  • Page 88: Usb Status Menu

    Chapter 5, FRONT PANEL OPERATION 5.3.19 USB Status Menu When the Configuration menu is displayed, pressing a key adjacent to the USB status item accesses the USB Status menu, which is shown in figure 5-25. Figure 5-25, USB Status Menu This menu has five indicators reporting the USB computer interface status and a key for accessing the Communications Monitor display, as follows:- Manufact.

  • Page 89: Communications Monitor

    Chapter 5, FRONT PANEL OPERATION 5.3.20 Communications Monitor When the Communications Menu is displayed, pressing the Communications monitor key accesses the Communications monitor display, shown in figure 5-26. It may also be accessed via the RS232 Settings and USB Status menus. Figure 5-26, Communications Monitor The monitor is useful when attempting to establish communications via the computer interfaces for the first time, or if a problem is suspected.

  • Page 90: Configuration Menu 2

    Chapter 5, FRONT PANEL OPERATION Figure 5-27, Options Menu The options menu is used to install additional firmware options and shows which options are already fitted (note that currently there are no options available, but the screen is provided to allow for future developments). If an option is purchased at the same time as the instrument, then the factory will install it and no further action is required.

  • Page 91: Spectral Display

    Positive operation is the same as earlier SIGNAL RECOVERY lock-in amplifiers, such as the models 7220, 7225, 7265, 7265, 7280, 5209 and 5210. When set to Negative it is the same as earlier versions of firmware in the models 7270, 7124 and 7230.
  • Page 92 2 kHz, the nominal range is 0 kHz to 458.0 kHz, although frequencies above 150 kHz are not usually of interest since they lie outside the frequency range of signals that the 7124 can measure. With the finest resolution of 0.2 kHz, the display range is nominally 45.8 kHz.

  • Page 93: Main Menu 2

    Chapter 5, FRONT PANEL OPERATION be updated. LIVE FFT When the key adjacent to the Live FFT control is pressed, the instrument acquires data repeatedly, performs an FFT on it and displays the resulting spectrum until the Stop key is pressed. NOTE: Live data acquisition is not available at 0.2 kHz and 0.4 kHz measurement resolutions.
  • Page 94 Chapter 5, FRONT PANEL OPERATION Figure 5-30, Main Menu 2 Main Menu 2 has keys used to access the extended features found in the model 7124, via a series of sub-menus. The relationship of these sub-menus to Main Menu 2 is shown in figure 5-31.

  • Page 95: Curve Buffer Menu

    FPGA memory, with the fastest time per point being reduced to 1 µs. Fast mode is a new mode in the model 7124 but in some ways can be considered as an extension to the Transient Recorder mode found in earlier SIGNAL RECOVERY DSP lock-in amplifiers.

  • Page 96: Curve Trigger Menu

    Chapter 5, FRONT PANEL OPERATION RISING EDGE EXTERNAL Acquisition starts on receipt of the rising edge of TTL trigger signal at the TRIG IN connector on the rear panel of the main console. FALLING EDGE EXTERNAL Acquisition starts on receipt of a falling edge of TTL trigger signal at the TRIG IN connector on the rear panel of the main console.
  • Page 97 Chapter 5, FRONT PANEL OPERATION Figure 5-33, Curve Trigger Menu The Curve Trigger menu is used to control how trigger inputs affect the curve buffer, and the position and polarity of the trigger output. ACQUISITION TRIGGER The acquisition trigger is a "per curve" (start) or "per point" (sample) trigger detecting the signal at the TRIG IN connector on the rear panel of the main console, as follows: INTERNAL...

  • Page 98: Curve Select Menu

    Chapter 5, FRONT PANEL OPERATION CURVE BUFFER FULL The curve buffer acquisition continues until the number of points acquired equals the curve length setting. ON TRIG IN The curve buffer acquisition continues until detection of a falling edge on the TTL trigger signal.
  • Page 99 Chapter 5, FRONT PANEL OPERATION Figure 5-34, Curve Select Menu - Standard Mode Figure 5-35, Curve Select Menu - Fast Mode For the standard mode, this menu is used to select the instrument outputs that will be stored when data acquisition to the curve buffer is initiated. The possible data types (outputs) that can be stored to the curve buffer are shown on the upper part of the screen.

  • Page 100: Single Graph Menu

    Chapter 5, FRONT PANEL OPERATION 5.3.28 Single Graph Menu When Main Menu 2 is displayed, pressing a key adjacent to the Single Graph item accesses the Single Graph menu, which is shown in figure 5-36. Figure 5-36, Single Graph Menu The Single Graph menu plots the data of one curve stored in the curve buffer.

  • Page 101: Double Graph Menu

    Chapter 5, FRONT PANEL OPERATION START/STOP keys In the single graph display mode, acquisition to the curve buffer, and hence display of data, can be controlled using the Start and Stop keys. CURSOR keys The bottom right-hand keys and the cursor-movement keys move the displayed cursor, which is only active when data is not being stored, from side to side.

  • Page 102: User Settings Menu

    Chapter 5, FRONT PANEL OPERATION SCALE keys The keys to the left-hand side of the display are used to set the upper and lower limits of the vertical axis in 1% increments, with the top and upper-middle keys being used for the upper curve (Curve 1) and the lower-middle and bottom keys for the lower curve (Curve 2).

  • Page 103: Adc Menu

    Chapter 5, FRONT PANEL OPERATION Figure 5-38, User Settings Menu - Save Settings To use the user settings feature, proceed as follows: Saving an Instrument Setting Press the Save settings key, which will cause the Memory keys to appear. Press either side of the key next to the Memory number in which the settings are to be stored.
  • Page 104 Chapter 5, FRONT PANEL OPERATION Figure 5-39, ADC Menu The ADC menu has a control to set the auxiliary ADC inputs trigger mode, an indicator showing the effecting time per point, four displays to show the voltages at the main console rear-panel ADC1 to ADC4 inputs and a key to access the Curve Buffer menu.

  • Page 105: Dac Menu

    Chapter 5, FRONT PANEL OPERATION TIME PER POINT This indicator shows the effective ADC sampling rate. Pressing the Curve buffer menu item access the Curve Buffer Menu, while pressing the Previous Menu key returns control to Main Menu 2. 5.3.32 DAC Menu When the Main Menu 2 is displayed, pressing a key adjacent to the DAC Menu item accesses the DAC Menu, shown in figure 5-40.
  • Page 106 Chapter 5, FRONT PANEL OPERATION DAC Voltage +300 7.5 V +100 2.5 V 0.0 V -100 -2.5 V -300 -7.5 V Y% (2.5V fs) When set to Y1% the corresponding DAC connector on the rear panel of the main console outputs a voltage related to the Y%fs front panel display as follows:- DAC Voltage +300...
  • Page 107 Chapter 5, FRONT PANEL OPERATION RATIO (2.5V fs) When set to RATIO the corresponding DAC connector on the rear panel of the main console outputs a voltage related to the result of the RATIO calculation, which is defined as follows:- ...
  • Page 108 Chapter 5, FRONT PANEL OPERATION value is defined as follows:- LOG RATIO DAC Voltage +2.000 2.000 V 0.0 V -3.000 -3.000 V Note: If RATIO < 0 then LOG RATIO = -3.000 EQUATION #1 When set to EQUATION #1 the corresponding DAC connector on the rear panel of the main console outputs a voltage related to Equation 1, which is defined using the Output Equations menu (see section 5.3.08), as follows:- EQUATION #1...

  • Page 109: Digital Port Menu

    Chapter 5, FRONT PANEL OPERATION 5.3.33 Digital Port Menu When Main Menu 2 is displayed, pressing a key adjacent to the Digital Port menu item accesses the Digital Port menu, shown in figure 5-41. Figure 5-41, Digital Port Menu The Digital Port menu allows the operating mode of each of the eight pins of the DIGITAL I/O connector on the rear panel of the main console to be set and its logic status to be set and read.

  • Page 110: Rcu Digital Port Menu

    The Digital Port menu allows the logic status of each of the eight pins of the DIGITAL I/O connector on the rear panel of the 7124 RCU to be set. This port may be used for controlling or reading the status of external equipment, for example the switching of heaters or attenuators, via a suitable user-supplied external interface circuit.

  • Page 111: Menu Descriptions - Virtual Reference Mode

    Chapter 5, FRONT PANEL OPERATION Figure 5-43, Fiber Calibration Menu The analog fiber links between the 7124 RCU and the main console are subject to change in transmission each time the fiber connectors are detached and reattached. The Fiber Calibration menu allows these changes to be calibrated out of the system Press one of the keys adjacent to the Start item to start the calibration.
  • Page 112 Chapter 5, FRONT PANEL OPERATION Figure 5-44, Virtual Reference Menu Structure When the Configuration menu is displayed and the Virtual Reference key is pressed, the Virtual Reference menu, shown in figure 5-45, will appear. Figure 5-45, Virtual Reference Menu This menu has six controls affecting the virtual reference mode, a single display, and two keys to establish virtual lock.
  • Page 113 Chapter 5, FRONT PANEL OPERATION TIME/STEP This control defines the time per point within the automatic search. Note that it should only be adjusted after a search has begun if it is taking a long time to find the signal. START AUTO SEARCH Pressing the Start Auto Search key starts the internal oscillator at the defined start frequency and increases it at a rate of 1 Hz per second.

  • Page 114: Virtual Reference Main Display

    The signals at the OSC OUT connector on the front panel of the main console or at the 7124 RCU (depending on which output is activated) and the REF MON connector on the rear panel are at the virtual reference frequency.

  • Page 115: Virtual Reference Configuration Menu

    5.5 Menu Descriptions - Dual Reference Mode 5.5.01 Dual Reference Setup Menu The dual reference mode allows the model 7124 to simultaneously measure signals applied to the signal input at two different reference frequencies. The source of these reference signals is two from the five available options of Internal, External Front Panel (main console), External Rear Panel (main console), External Front Panel (RCU), and External Rear Panel (RCU).

  • Page 116: Dual Reference Main Display

    Chapter 5, FRONT PANEL OPERATION Figure 5-48, Dual reference Setup Menu 5.5.02 Dual Reference Main Display Once dual reference has been activated, the Main Display - Dual reference Mode is displayed, as shown in figure 5-49. Figure 5-49, Main Display - Dual Reference Mode In dual reference mode, controls and displays relating to the reference channel 1 signal carry the suffix "1"...
  • Page 117 127 th. RELOCK EXT. REFERENCE The 7124 includes frequency-dependent calibration parameters. In Dual reference mode the correct parameters can be chosen for the internal reference channel because its frequency is equal to the specified oscillator frequency. The parameters for the...
  • Page 118 Keypad or Active Cursor controls - see section 4.1.04. RCU OSC AMPLITUDE This control sets the amplitude of the signal at the 7124 RCU’s OSC OUT connector to any value between 1 mV and 5 V rms. Adjustment is faster using the Keypad or Active Cursor controls - see section 4.1.04.
  • Page 119 DAC connectors on the rear panel of the main console as an analog voltage. Note: Unless both the 7124 Main Console AUX input and one of the 7124 RCU’s inputs are being used as signal inputs, the signals at the two frequencies that are...

  • Page 120: Dual Reference Channel Menu

    Chapter 5, FRONT PANEL OPERATION being measured share a common signal path and hence controls affecting the signal channel, such as signal source, AC Gain and the line filter controls, apply to both reference frequencies. Although the full-scale sensitivity setting can be independently set for both references, the maximum AC Gain that is possible is defined by the least sensitive setting of the two.
  • Page 121 EXTr RCU In this setting the reference 1 channel is configured to accept a suitable external reference source applied to the 7124 RCU rear panel TTL REF IN input connector. EXTf RCU In this setting the reference 1 channel is configured to accept a suitable external reference source applied to the 7124 RCU front panel REF IN input connector.

  • Page 122: Dual Reference Channel Menu 2

    Chapter 5, FRONT PANEL OPERATION Pressing the Previous Menu key returns control to Main Menu 1. 5.5.04 Dual Reference Channel Menu 2 Figure 5-52, Dual Reference Channel Menu 2 The Dual Reference Channel Menu 2, shown above in figure 5-52, has four controls affecting the instrument's reference channel, and a key to access Dual Reference Channel Menu 1.
  • Page 123 Chapter 5, FRONT PANEL OPERATION Figure 5-53, Dual Reference Output Filters Menu 1 The Dual Reference Output Filters Menu 1 has four controls affecting the instrument's output low-pass filters, and a key to access Output Filters Menu 2. Changes to the setting of these controls can be made by using the adjacent keys.

  • Page 124: Dual Reference Output Filters Menu 2

    Chapter 5, FRONT PANEL OPERATION FAST In this setting, the analog outputs are derived directly from the core FPGA running the demodulator algorithms. The update rate is increased to 1.0 MHz when the time constant is set to any value from 10 µs to 500 ms but reverts to 1 kHz for longer time constants.
  • Page 125 Chapter 5, FRONT PANEL OPERATION Figure 5-55, Output Offset Ref 1 Menu The Output Offset Ref 1 menu has three controls affecting the instrument's X1 channel and Y1 channel outputs and a key to access a further sub-menu which has corresponding controls for the X2 channel and Y2 channel. Changes to the setting of these controls can be made by using the adjacent keys, with the currently active selection being highlighted.

  • Page 126: Dual Reference Output Offset Ref 2 Menu

    Chapter 5, FRONT PANEL OPERATION settle. Pressing the Output Offset Ref 2 key accesses the Output Offset Ref 2 menu, and pressing the Previous Menu key returns control to Main Menu 1. 5.5.08 Dual Reference Output Offset Ref 2 Menu In dual reference mode, when Output Offset Ref 1 Menu is displayed, pressing the Output Offset Ref 2 Menu key accesses the Output Offset Ref 2 menu, which is shown in figure 5-56.

  • Page 127: Dual Reference Auto Functions Menus

    Chapter 5, FRONT PANEL OPERATION The Y2 channel output offset is switched on. X&Y2 Both X2 channel and Y2 channel output offsets are switched on. AUTO OFFSET2 This control adjusts the X2 offset and Y2 offset values so that the X2 channel and Y2 channel outputs are zero.

  • Page 128: Dual Reference Configuration Menu

    Chapter 5, FRONT PANEL OPERATION 5.5.10 Dual Reference Configuration Menu Figure 5-58, Configuration Menu - Dual reference Mode In dual reference mode, the Configuration menu appears as above. To leave dual reference mode and return to single reference mode press the Single Reference key, to switch to dual harmonic mode, press the Dual Harmonic key.

  • Page 129: Dual Reference And Dual Harmonic Modes Dac Menu

    Chapter 5, FRONT PANEL OPERATION Figure 5-60, Curve Select Menu - Fast Mode For the standard mode, this menu is used to select the instrument outputs that will be stored when data acquisition to the curve buffer is initiated. The possible data types (outputs) that can be stored to the curve buffer are shown on the upper part of the screen.
  • Page 130 Chapter 5, FRONT PANEL OPERATION Figure 5-61, DAC Menu - Dual Reference and Dual Harmonic Modes The DAC menu is used to configure the signal that will appear on the four DAC connectors on the rear panel of the main console. On the left hand side of the panel four controls are used to set the DC voltages of the auxiliary DAC outputs, while on the right hand side four controls are used to select the signal that will actually be applied to the DAC 1 to DAC 4 connectors.
  • Page 131 Chapter 5, FRONT PANEL OPERATION DAC Voltage +300 7.5 V +100 2.5 V 0.0 V -100 -2.5 V -300 -7.5 V MAG1% (2.5V fs) When set to MAG1% the corresponding DAC connector on the rear panel of the main console outputs a voltage related to the MAG1%fs or R % front panel displays as follows:- MAG1%fs...
  • Page 132 Chapter 5, FRONT PANEL OPERATION instrument were measuring a 100 mV signal when set to the 500 mV sensitivity setting, the X1 channel output were maximized and a 1 V signal were applied to the ADC1 input, then the value of RATIO would be:- ...

  • Page 133: Menu Descriptions - Dual Harmonic Mode

    5.6 Menu Descriptions - Dual Harmonic Mode 5.6.01 Dual Harmonic Setup Menu The dual harmonic mode allows the model 7124 to simultaneously measure signals applied to the signal input at two different harmonics of the reference frequency. The reference may be either externally supplied or derived from the internal oscillator.

  • Page 134: Dual Harmonic Main Display

    Chapter 5, FRONT PANEL OPERATION sections. The remaining menus operate in the same way as in single reference mode, as already described in section 5.3. When the Configuration menu is displayed, pressing the Dual Harmonic key activates the dual harmonic mode. While the instrument switches to this mode, the Dual Harmonic Setup menu is displayed, as shown in figure 5-62.
  • Page 135 Chapter 5, FRONT PANEL OPERATION using the Select Control key is therefore extended to include those relating to both harmonics of the reference, as follows:- SENSITIVITY 1 and SENSITIVITY 2 When set to voltage input mode, using the Signal Channel menu, the instrument's full-scale voltage sensitivity may be set to any value between 10 nV and 1 V in a 1-2-5 sequence.
  • Page 136 Keypad or Active Cursor controls - see section 4.1.04. RCU OSC AMPLITUDE This control sets the amplitude of the signal at the 7124 RCU’s OSC OUT connector to any value between 1 mV and 5 V rms. Adjustment is faster using the Keypad or Active Cursor controls - see section 4.1.04.
  • Page 137 DAC connectors on the rear panel of the main console as an analog voltage. Note: Unless both the 7124 Main Console AUX input and one of the 7124 RCU’s inputs are being used as signal inputs, the signals at the two harmonics that are...

  • Page 138: Dual Harmonic Reference Channel Menu

    Chapter 5, FRONT PANEL OPERATION to both harmonics. Although the full-scale sensitivity setting can be independently set for both harmonics, the maximum AC Gain that is possible is defined by the least sensitive setting of the two. 5.6.03 Dual Harmonic Reference Channel Menu In dual harmonic mode, the reference channel is controlled by the Dual Harmonic Reference menu, which differs from the Reference Channel menu used in the other three modes.
  • Page 139 7124 RCU front panel REF IN input connector EXTr In this setting the reference channel is configured to accept a suitable external reference source applied to the 7124 main console rear panel TTL REF IN input connector EXTf...

  • Page 140: Dual Harmonic Output Filters Menu

    Chapter 5, FRONT PANEL OPERATION and 127th. Adjustment is faster using the Keypad or Active Cursor controls - see section 4.1.04. HARMONIC 1 PHASE and HARMONIC 2 PHASE These two controls allow the reference phase of harmonic and harmonic to be independently adjusted over the range -180°...

  • Page 141: Dual Harmonic Output Filters Menu 2

    Chapter 5, FRONT PANEL OPERATION In this setting, the actual time constant used is chosen to be some multiple of the reference frequency period, giving a much more stable output at low frequencies than would otherwise be the case. Note that, depending on the reference frequency, output time constants shorter than 100 ms cannot be used.

  • Page 142: Dual Harmonic Output Offset Harm 1 Menu

    Chapter 5, FRONT PANEL OPERATION set the time constant of each of the output filters. SLOPE 2 The roll-off of the outputs filters can be set, using this control, to either 6 dB or 12 dB per octave (Fast time constant mode) or 6 dB, 12 dB, 18 dB or 24 dB per octave (Normal time constant mode).

  • Page 143: Dual Harmonic Output Offset Harm 2 Menu

    Chapter 5, FRONT PANEL OPERATION NONE Both X1 channel and Y1 channel output offsets are switched off. The X1 channel output offset is switched on. The Y1 channel output offset is switched on. X1&Y1 Both X1 channel and Y1 channel output offsets are switched on. AUTO OFFSET1 This control adjusts the X1 offset and Y1 offset values so that the X1 channel and Y1 channel outputs are zero.

  • Page 144: Dual Harmonic Auto Functions Menus

    Chapter 5, FRONT PANEL OPERATION The values are set automatically by the Auto-Offset 2 function, which also switches on both X2 channel and Y2 channel output offsets. OFFSET 2 STATUS This control allows the X2 channel and Y2 channel output offsets, set by the above level controls, to be switched on to either or both outputs, or to be switched off.

  • Page 145: Dual Harmonic Configuration Menu

    This completes the description of the dual harmonic mode menus. 5.7 Typical Lock-in Amplifier Experiment The model 7124 is a complex instrument that has many controls and the following basic checklist may be helpful in setting up the instrument for manual operation in single reference mode.
  • Page 146 Chapter 5, FRONT PANEL OPERATION If using external reference mode, use the Reference Channel menu to select one of the four external inputs, and connect the reference signal to the correct connector. Auto-Measure Use the Auto-Measure function on the Auto Functions menu to set the instrument so that it is correctly displaying the signal.

  • Page 147: Introduction

    Chapter 6.1 Introduction The model 7124 includes RS232, USB and Ethernet interface ports, designed to allow it to be completely controlled from a remote computer. Virtually all of the instrument's controls may be operated, and all of the outputs can be read, via these interfaces.

  • Page 148: General Features

    In the model 7124 the baud rate can be set to a range of different values up to 38,400, corresponding to a minimum time of less than 0.25 ms for a single character.

  • Page 149: Choice Of Parity Check Option

    Therefore no software is provided in the model 7124 for dealing with parity errors. Where long cables are in use, it may be advisable to make use of a lower baud rate. The result is that any of the parity check options may be used, but the no-parity option will result in slightly faster communication.

  • Page 150: Terminators

    Chapter 6, COMPUTER OPERATION faster than the lock-in amplifier and bytes can easily be lost if the command is sent from a program. (Note that because of the limited speed of human typing, there is no problem in the terminal mode.) To overcome the problem an echo handshake should be used.

  • Page 151: Usb Operation

    VISA software driver is the need to download and install the complete VISA environment in order to use the driver. Readers should refer to the document “USB Drivers for the Model 7124 and 7270 Lock-in Amplifiers”, available from the www.signalrecovery.com website, for further information about installing these drivers.

  • Page 152: Delimiters

    Chapter 6, COMPUTER OPERATION Responses from the instrument consist of a string that is terminated with one or three bytes depending on the setting of the Output Terminator control on the USB Status Menu – see section 5.3.19 – as follows: Output Terminator = NULL 1) A null character (ASCII 0) Output Terminator = STATUS...

  • Page 153: Ethernet Operation

    Chapter 6, COMPUTER OPERATION 6.5 Ethernet Operation 6.5.01 Introduction The Ethernet interface in the instrument supports operation on 10-BaseT and 100- BaseT networks via straight through or crossover RJ45 patch cables. The instrument includes a built-in web server allowing any browser to communicate with it using http protocol, as well as socket support for direct communication via TCP/IP.

  • Page 154: Sockets

    Chapter 6, COMPUTER OPERATION Figure 6-1, Built-in Home Page 6.5.04 Sockets The instrument normally accepts commands sent to socket 50000 or socket 50001 on its IP address. Any response is sent back to the IP address from which the initiating command was sent.

  • Page 155: Delimiters

    Chapter 6, COMPUTER OPERATION 1) A carriage return character (CR - ASCII 13) In the case of commands that generate a single response, the controlling program should send the null-terminated command string to the instrument and then read the response bytes sent back from it. If using port 50000, read until the null is detected. Two further bytes (the status and overload bytes) should then be read to complete the transfer.

  • Page 156: Command Descriptions

    Chapter 6, COMPUTER OPERATION appending a . (full stop) character to the end of the command and before the parameters. This allows some parameters to be entered or read in floating point format. The floating point output format is given below. ±1.234E±01 The number of digits between the decimal point and the exponent varies depending on the number but is a minimum of one and a maximum of eight.
  • Page 157 Float (connected to ground via a 1 k resistor) FET [n] ] FET input selection The value of n control the input device used at the signal input on the 7124 RCU according to the following table: Input device Bipolar SEN [n] SEN.

  • Page 158: Reference Channel

    Chapter 6, COMPUTER OPERATION Floating point mode can only be used for reading the sensitivity, which is reported in volts or amps. For example, if IMODE = 0 and the sensitivity is 1 mV the command SEN would report 18 and the command SEN. would report +1.0E-03. If IMODE was changed to 1, SEN would still report 18 but SEN.
  • Page 159 EXT (external rear panel TTLREF IN input on Main Console) EXT (external front panel analog REF input on Main Console) EXT (external rear panel TTLREF IN input on 7124 RCU) EXT (external front panel analog REF input on 7124 RCU)

  • Page 160: Signal Channel Output Filters

    Chapter 6, COMPUTER OPERATION FRQ[.] Reference frequency meter If the lock-in amplifier is in the external reference source modes, the FRQ command causes the lock-in amplifier to respond with 0 if the reference channel is unlocked, or with the reference input frequency if it is locked. If the lock-in amplifier is in the internal reference source mode, it responds with the frequency of the internal oscillator.

  • Page 161: Signal Channel Output Amplifiers

    Chapter 6, COMPUTER OPERATION 100 µs 20 s 200 µs 50 s 500 µs 500 µs 100 s 1 ms 1 ms 200 s 2 ms 2 ms 500 s 5 ms 5 ms 1 ks 10 ms 10 ms 2 ks 20 ms 5 ks...
  • Page 162 Chapter 6, COMPUTER OPERATION Selection Disables offset facility Enables offset facility The range of n is ±30000 corresponding to ±300% full-scale. Auto-Offset The X and Y channel output offsets are turned on and set to levels giving zero X and Y channel outputs.

  • Page 163: Instrument Outputs

    Chapter 6, COMPUTER OPERATION FASTMODE [n] Output Filter Mode Control The value of n sets the output filter mode control according to the following table: Function Fast mode off Fast mode on When the fast analog output mode is turned off, the available output filter time constant is restricted to 5 ms or greater, but all four filter slopes are available (i.e.
  • Page 164 Chapter 6, COMPUTER OPERATION and ADC1 is the value that would be returned by the ADC1 command. The response range is -3000 to +2079 In floating point mode, the LR. command reports a number equivalent to log(X/ADC1). The response range is -3.000 to +2.079 NHZ.

  • Page 165: Internal Oscillator

    Mode Oscillator at main console OSC OUT connector Oscillator at 7124 RCU OSC OUT connector OA[.] [n] Oscillator amplitude control In fixed point mode n sets the oscillator amplitude in mV. The range of n is 0 to 5000 representing 0 V to 5 V rms.
  • Page 166 Chapter 6, COMPUTER OPERATION in the range 0 to 5.000 V In fixed point mode, n is in millivolts rms, and in floating point mode n is in volts ASTOP[.] [n] Oscillator amplitude sweep stop amplitude Sets the stop amplitude for a subsequent sweep of the internal oscillator amplitude, in the range 0 to 5.000 V In fixed point mode, n is in millivolts rms and in floating point mode n is in volts rms ASTEP[.] [n]...
  • Page 167 Chapter 6, COMPUTER OPERATION SWEEP [n] Oscillator frequency and amplitude sweep control Sweep status Stop Start/continue frequency sweep Start/continue amplitude sweep Start/continue frequency sweep and amplitude sweep Pause frequency sweep Pause amplitude sweep Pause frequency sweep and amplitude sweep Link frequency sweep to curve buffer acquisition 10 Link amplitude sweep to curve buffer acquisition 11 Link frequency and amplitude sweep to curve buffer acquisition This command is used to start or stop the internal oscillator frequency or amplitude...
  • Page 168 Chapter 6, COMPUTER OPERATION AMFILTER [n] Oscillator amplitude modulation filter control command The value of n sets the oscillator amplitude modulation voltage low-pass filter control in the range 0 to 10. The value of 0 gives the widest bandwidth for this filter, with the value of 10 the lowest.

  • Page 169: Analog Outputs

    Chapter 6, COMPUTER OPERATION 6.7.07 Analog Outputs CH n DAC analog output control Defines what outputs appear on the DAC1, DAC2, DAC3 and DAC4 connectors on the rear panel. Signal (DAC1) X % (2.5 V FS) Noise % (2.5 V FS) Ratio: (10 ×...

  • Page 170: Digital I/O

    RCUBYTE [n] 7124 RCU Digital port output control The value of n, in the range 0 to 255, determines the bits to be output at the 7124 RCU rear panel digital port. 6.7.09 Auxiliary Inputs ADC[.] n...

  • Page 171: Output Data Curve Buffer

    Chapter 6, COMPUTER OPERATION TADC [n] Auxiliary analog-to-digital input trigger mode The value of n sets the trigger modes for the auxiliary ADC inputs according to the following table: Trigger Mode Internal (1 kHz) External - apply trigger to ADC TRIG IN connector Burst ADC1 (5 µs per point, only ADC1 is converted) Burst ADC1 &...
  • Page 172 Chapter 6, COMPUTER OPERATION Dual modes only:- Bit Decimal value Output and range 131072 Output (±10000 FS) 262144 Output (±10000 FS) 524288 Magnitude2 Output (0 to +10000 FS) 1048576 Phase Output (±18000 = ±180°) 2097152 Sensitivity setting (3 to 27) + IMODE (0, 1, 2 = 0, 32, 64) 100,000 points are available for data storage in the standard curve buffer mode,, shared equally between the specified curves.
  • Page 173 Chapter 6, COMPUTER OPERATION oscillator frequency and/or amplitude sweep has been defined and linked to the curve buffer using the SWEEP command with a parameter of 9, 10 or 100, then this sweep will be started as well. TDT n Take data triggered Sets the instrument so that data acquisition is initiated on receipt of various trigger conditions at the TRIG connector on the rear panel.
  • Page 174 Chapter 6, COMPUTER OPERATION TRIGOUT [n] Curve buffer trigger output The value of n defines the type of trigger output generated when a buffer acquisition is run in accordance with the following table: Trigger Trigger generated once per curve, at start of curve Trigger generated once per point TRIGOUTPOL [n] Curve buffer trigger output polarity...
  • Page 175 Chapter 6, COMPUTER OPERATION Fourth value, Number of Points Acquired: This number is incremented each time a point is taken. It is zeroed by the NC command and whenever CBD or LEN is applied without parameters. DC[.] n Dump acquired curve(s) to computer The operation of this command depends on whether data has been stored into the Standard or Fast Mode curve buffers.
  • Page 176 Chapter 6, COMPUTER OPERATION DCCOUPLE [n] Input coupling control The value of n sets the input coupling mode according to the following table: Coupling mode AC coupled DC coupled DCB n Dump acquired curve(s) to computer in binary format The operation of this command depends on whether data has been stored into the Standard or Fast Mode curve buffers.
  • Page 177 Chapter 6, COMPUTER OPERATION Output and range X Output (±10000 FS) Y Output (±10000 FS) Main signal channel ADC output (digital signal monitor 1 ADC1 (±10000 = ±10.0 V) ADC2 (±10000 = ±10.0 V) Dual modes only:- Output (±10000 FS) Output (±10000 FS) Input to second demodulator (digital signal monitor 2) The computer program's subroutine which reads the responses to the DC command...

  • Page 178: Computer Interfaces

    Byte (table 6-1) \N n Address command When the model 7124 is daisy-chained with other compatible instruments this command will change which instrument is addressed. All daisy-chained instruments receive commands but only the currently addressed instrument will implement or respond to the commands. The exception is the \N n command. If n matches the...
  • Page 179 Chapter 6, COMPUTER OPERATION address set from the front panel the instrument will switch into addressed mode. If n does not match the address set from the front panel the instrument will switch into unaddressed mode. Note that the \N n command does not change the address of an instrument but which instrument is addressed.

  • Page 180: Instrument Identification

    The value of n controls the front panel LCD display according to the following table: Selection Display off Normal operation LTSRCU [n] RCU LED on/off control The value of n controls the LED on the front panel of the 7124 RCU according to the following table: Selection LED always off Normal operation PAGE [n] Front panel display page number This command sets or reads the “page number”...

  • Page 181: Dual Mode Commands

    Chapter 6, COMPUTER OPERATION 6.7.15 Dual Mode Commands When either dual reference or dual harmonic modes are selected, some commands change so that both channels can be controlled independently, as listed in the following table: Single Reference or Dual Reference or Virtual Reference mode command Dual Harmonic mode command not available...

  • Page 182: Programming Examples

    Chapter 6, COMPUTER OPERATION 6.5 Programming Examples 6.5.01 Introduction This section gives some examples of the commands that need to be sent to the lock- in amplifier for typical experimental situations. 6.5.02 Basic Signal Recovery In a typical simple experiment, the computer is used to set the instrument controls and then to record the chosen outputs, perhaps as a function of time.

  • Page 183: And Y Output Curve Storage Measurement

    Chapter 6, COMPUTER OPERATION Auto-Phase The frequency sweep would be performed and the outputs recorded by sending the following commands from a FOR...NEXT program loop: OF. XX Set oscillator frequency to new value XX hertz Software delay of 200 ms (4 × 50 ms) allowing output to stabilize MAG.
  • Page 184 Chapter 6, COMPUTER OPERATION 6-38...

  • Page 185: Appendix A, Specifications

    Specifications Appendix Measurement Modes X In-phase Y Quadrature The unit can simultaneously show any R Magnitude four of these outputs on the front panel  Phase Angle display Noise nF, n  127 Harmonic Dual Harmonic Simultaneously measures the signal at two different harmonics F and F of the reference frequency...
  • Page 186 Appendix A, SPECIFICATIONS Signal Channel - Remote Connection Unit Voltage Inputs Modes A only, -B only or Differential (A-B) 0.5 Hz  F  150 kHz (–3 dB) Frequency Response Full-scale Sensitivity 10 nV to 1 V in a 1-2-5 sequence (e.g. 2 nV, 5 nV, 10 nV) Input Impedance FET Input...
  • Page 187 Appendix A, SPECIFICATIONS Signal Monitor Amplitude ±1 V FS. This is the signal received from the Remote Connection Unit immediately prior to conversion by the main ADC Output Impedance 1 k Reference Input - Remote Connection Unit or Main Console TTL Input (rear panel) Frequency Range 0.5 Hz to 150 kHz (3.0 kHz in Dual...
  • Page 188 Appendix A, SPECIFICATIONS Oscillator - General Frequency Range 0.5 Hz to 150 kHz Setting Resolution 1 mHz Absolute Accuracy ± 50 ppm Amplitude Range 1 mV to 5 V Setting Resolution 1 mV 50  Output Impedance Sweep Frequency Output Range 0.5 Hz to 150 kHz Linear or Logarithmic Step Rate...
  • Page 189 Appendix A, SPECIFICATIONS Output Functions Noise, Ratio, Log Ratio and User Equations 1 & 2. Amplitude X(1), Y(1), Mag(1), Pha(1) ±2.5 V full-scale; linear to ±300% F.S. User DACs and Output Functions ±11.0 V full-scale Impedance 1 k Update Rate X(1/2), Y(1/2), Mag(1/2), Pha(1/2) @ TC <...
  • Page 190 Voltage 110/120/220/240 VAC 110/120/220/240 VAC Frequency 50/60 Hz 50/60 Hz Power 40 VA max 15 VA max RCU with option 7124/99 Voltage ±24.0 V DC +300 mA / –170 mA Current Dimensions Width 15½" (390 mm) 15½" (390 mm) Depth 7¼"...

  • Page 191: Appendix B, Pinouts

    Pins 4 and 5 are not connected. Shell is shield ground. When the model 7124/99 option is fitted, the connector on the rear panel of the 7124 RCU is also used to power the unit, and has the following pinout: Function –15 V Output...
  • Page 192 If configured as an output, the bit status can be set, and if configured as an input it can be read, from the front panel or via the computer interfaces. On the 7124 RCU each bit can only be used as an output.

  • Page 193: Appendix C, Cable Diagrams

    Appendix C.1 RS232 Cable Diagrams Users who choose to use the RS232 interface to connect the model 7124 lock-in amplifier to a standard serial port on a computer will need to use one of two types of cable. The only difference between them is the number of pins used on the connector which goes to the computer.
  • Page 194 Appendix C, CABLE DIAGRAMS Figure C-2, Interconnecting RS232 Cable Wiring Diagram...

  • Page 195: Appendix D, Default Settings

    Default Settings Appendix Auto Default Function The Auto-Default computer command ADF 1 sets the model 7124's controls and output displays as follows:- Main Display Displays the AC Gain, full-scale sensitivity, reference phase, time constant, reference phase and oscillator frequency controls on the left-hand side. On the right-...
  • Page 196 Appendix D, DEFAULT SETTINGS Output Equations ((X-X)  X)/X = zero Equation #1 ((X-X)  X)/X = zero Equation #2 Equns 1 & 2 C1, C2 Oscillator RCU Oscillator Frequency Sweep Start Frequency 0.000 Hz Stop Frequency 0.000 Hz Step Size 0.000 Hz Time/Step 0.000 s...
  • Page 197 Computer IP Address 000.000.000.000 USB Status Terminator Null, Status & Overload bytes The ADF 2 computer command sets the model 7124's controls and output displays as for the ADF 0 command, except that the oscillator amplitude is set to 0 V rms.
  • Page 198 Appendix D, DEFAULT SETTINGS...

  • Page 199: 7124/99 Dc Power Input Cable

    7124 RCU. Note that although rechargeable batteries can be used for the DC supplies, there is no provision for the 7124 RCU to recharge these batteries when it is connected to line power.

  • Page 200: Operation

    130mA Table E-1, 7124 RCU DC Input Voltage Specifications d) Verify that that the 7124 RCU is disconnected from the line power supply. e) Plug the 5-pin DIN plug on the Power Input Cable into the POWER IN/OUT connector on the rear panel of the 7124 RCU.

  • Page 201: Line Power/Dc Input Power Switching

    As mentioned in the operating procedure at section E.5 above line power should not be applied to the line input socket when the 7124 RCU is powered via the external DC input. Similarly when running the unit from line power, the external battery power cable should not be connected.
  • Page 202 Appendix E, 7124/99 DC POWER OPTION FOR 7124RCU...
  • Page 203 Alphabetical Listing of Commands Appendix Fast Data Transfer command The ? command offers a method of reading a combination of instrument outputs which are sampled at the same time, thereby ensuring that they are correlated. The response to the ? command is the output(s), expressed in floating point mode, specified by the present setting of the Curve Buffer Define (CBD) command (see section 6.7.09) and separated by delimiter character(s) defined by the DD command.

  • Page 204: Appendix F, Alphabetical Listing Of Commands

    Appendix F, ALPHABETICAL LISTING OF COMMANDS AMFILTER [n] Oscillator amplitude modulation filter control command The value of n sets the oscillator amplitude modulation voltage low-pass filter control in the range 0 to 10. The value of 0 gives the widest bandwidth for this filter, with the value of 10 the lowest.
  • Page 205 Appendix F, ALPHABETICAL LISTING OF COMMANDS AUTOMATIC [n] AC Gain automatic control Status AC Gain is under manual control, either using the front panel or the ACGAIN command Automatic AC Gain control is activated, with the gain being adjusted according to the full-scale sensitivity setting Auto-Offset The X and Y channel output offsets are turned on and set to levels giving zero X and...
  • Page 206 Appendix F, ALPHABETICAL LISTING OF COMMANDS Bit Decimal value Output and range 2048 ADC4 (±10000 = ±10.0 V) 4096 DAC1 (±10000 = ±10.0 V) 8192 DAC2 (±10000 = ±10.0 V) 16384 EVENT variable (0 to 32767) 32768 Reference Frequency bits 0 to 15 (millihertz) 65536 Reference frequency bits 16 to 31 (millihertz) Dual modes only:-...
  • Page 207 Appendix F, ALPHABETICAL LISTING OF COMMANDS Signal (DAC1, n = 1) Main signal channel ADC output (digital signal monitor 1) Magnitude2 % (2.5 V FS) (dual mode only) Signal (DAC2, n = 2) Y % (2.5 V FS) Noise % (2.5 V FS) Ratio: (10 ×...
  • Page 208 Appendix F, ALPHABETICAL LISTING OF COMMANDS CP [n] Input connector coupling mode control The value of n sets the input coupling mode according to the following table: Coupling mode Fast Slow DAC[.] n Set user DAC output voltage controls The first parameter n , which specifies the DAC, is compulsory and is either 1, 2, 3 or 4.
  • Page 209 Appendix F, ALPHABETICAL LISTING OF COMMANDS Output and range X Output (±10000 FS) Y Output (±10000 FS) Main signal channel ADC output (digital signal monitor 1 ADC1 (±10000 = ±10.0 V) ADC2 (±10000 = ±10.0 V) Dual modes only:- Output (±10000 FS) Output (±10000 FS) Input to second demodulator (digital signal monitor 2) The computer program's subroutine which reads the responses to the DC command...
  • Page 210 Appendix F, ALPHABETICAL LISTING OF COMMANDS Reference Frequency = (65536 × value in Curve 16) + (value in Curve 15) The computer program's subroutine which reads the responses to the DCB command needs to be able to handle the potentially very large data blocks (200 k bytes in the case of one 100 k curve) that can be generated.
  • Page 211 Appendix F, ALPHABETICAL LISTING OF COMMANDS Bit Decimal value Output and range Ratio (±10000 FS) Log ratio (-3000 to +2000) ADC1 (±10000 = ±10.0 V) ADC2 (±10000 = ±10.0 V) 1024 ADC3 (±10000 = ±10.0 V) 2048 ADC4 (±10000 = ±10.0 V) 4096 DAC1 (±10000 = ±10.0 V) 8192...
  • Page 212 Appendix F, ALPHABETICAL LISTING OF COMMANDS Variable Range X or X1 ±30000 Y or Y1 ±30000 MAG or MAG1 0 to 30000 PHA or PHA1 ±18000 ADC1 ±10000 ADC2 ±10000 ADC3 ±10000 ADC4 ±10000 0 to 100000 0 to 100000 10 0 zero 11 1...
  • Page 213 10 µs can be selected, but the slope is limited to either 6 or 12 dB/octave. FET [n] ] FET input selection The value of n control the input device used at the signal input on the 7124 RCU according to the following table: Input device...
  • Page 214 Appendix F, ALPHABETICAL LISTING OF COMMANDS FMFILTER [n] Oscillator frequency modulation filter control command The value of n sets the oscillator frequency modulation voltage low-pass filter control in the range 0 to 10. The value of 0 gives the widest bandwidth for this filter, with the value of 10 the lowest.
  • Page 215 SWEEP command with a parameter of 9, 10 or 100, then this sweep will be stopped as well. Identification Causes the lock-in amplifier to respond with the number 7124. IE [n] Reference channel source control (Internal/External)
  • Page 216 Appendix F, ALPHABETICAL LISTING OF COMMANDS IMODE [n] Current/Voltage mode input selector The value of n sets the input mode according to the following table Input mode Current mode off - voltage mode input enabled High bandwidth current mode enabled - connect signal to B/I input connector Low noise current mode enabled - connect signal to B/I input connector If n = 0 then the input configuration is determined by the VMODE command.
  • Page 217 Selection Display off Normal operation LTSRCU [n] RCU LED on/off control The value of n controls the LED on the front panel of the 7124 RCU according to the following table: Selection LED always off Normal operation Curve acquisition status monitor...
  • Page 218 Equivalent to the compound command MAG[.];PHA[.] \N n Address command When the model 7124 is daisy-chained with other compatible instruments this command will change which instrument is addressed. All daisy-chained instruments receive commands but only the currently addressed instrument will implement or respond to the commands.
  • Page 219 Appendix F, ALPHABETICAL LISTING OF COMMANDS and 255, which is the decimal equivalent of a binary number with the following bit- significance: Bit 0 X channel output overload (> ±300 %FS) Bit 1 Y channel output overload (> ±300 %FS) Bit 2 X2 channel output overload (>...
  • Page 220 All lines configured as inputs RCUBYTE [n] 7124 RCU Digital port output control The value of n, in the range 0 to 255, determines the bits to be output at the 7124 RCU rear panel digital port. RCUOSC [n] RCU oscillator selection control...
  • Page 221 Appendix F, ALPHABETICAL LISTING OF COMMANDS port. Hence, for example, if PORTDIR = 255 and the response to READBYTE is 255, then all lines are high, and if the response to READBYTE is 0, then all lines are low. Note that because the command does not differentiate between whether a line is configured as an input or output, it can be used as a single command to determine the present status of all eight lines, both inputs and outputs, of the port.
  • Page 222 Appendix F, ALPHABETICAL LISTING OF COMMANDS RSADDR [n] Set/read RS232 address The value of n sets the RS232 address in the range 0 to 15. This is relevant only when using more than one instrument connected via the RS232 “daisy-chain” method.
  • Page 223 Appendix F, ALPHABETICAL LISTING OF COMMANDS table: Slope 6 dB/octave 12 dB/octave 18 dB/octave 24 dB/octave When: a) The fast output filter mode is turned on, or b) Noise measurement mode is turned ON (NOISEMODE 1) the selection is according to the following table: Slope 6 dB/octave 12 dB/octave...
  • Page 224 Appendix F, ALPHABETICAL LISTING OF COMMANDS Sweep status 10 Link amplitude sweep to curve buffer acquisition 11 Link frequency and amplitude sweep to curve buffer acquisition This command is used to start or stop the internal oscillator frequency or amplitude sweep, or to specify that the sweep should be linked to the curve buffer data acquisition.
  • Page 225 Appendix F, ALPHABETICAL LISTING OF COMMANDS NOISEMODE NOISEMODE NOISEMODE NOISEMODE 500 µs 500 µs 100 s 1 ms 1 ms 200 s 2 ms 2 ms 500 s 5 ms 5 ms 1 ks 10 ms 10 ms 2 ks 20 ms 5 ks 50 ms...
  • Page 226 Appendix F, ALPHABETICAL LISTING OF COMMANDS is simply when the number of points specified by the LEN command parameter have been acquired, but it is also possible to leave acquisition running until an HC command is sent or until either a rising or falling edge occurs at the trigger input. The trigger modes, set by the value of n, are as follows: Start condition Sample condition...
  • Page 227 Appendix F, ALPHABETICAL LISTING OF COMMANDS Input configuration Both inputs grounded (test mode) A input only (remote connection unit) -B input only (remote connection unit) A-B differential mode (remote connection unit) AUX input (main console) Note that the IMODE command takes precedence over the VMODE command. VRLOCK [n] Virtual reference mode lock The Seek option of the frequency sweep mode must be used before issuing this...
  • Page 228 Appendix F, ALPHABETICAL LISTING OF COMMANDS F-26...
  • Page 229 Index ? command 6-18, F-1 AMCENTERV command 6-20, F-1 \N n command 6-31, F-15 AMDEPTH command 6-20, F-1 7124 RCU Front Panel AMFILTER command 6-21, F-2 layout 4-8 AMSOURCE command 6-21, F-2 7124 RCU Rear Panel AMVSPAN command 6-21, F-2...
  • Page 230 INDEX alphabetical listing of F-1 DAC2 compound commands 6-1 connector 4-8 delimiters 6-4, 6-6, 6-9 control 5-51, 5-76 floating point mode 6-9 DAC3 for analog outputs 6-22 connector 4-8 for Auto-Default function and calibration 6-33 control 5-51, 5-76 for auxiliary inputs 6-23 DAC4 for computer interfaces 6-31 connector 4-8...
  • Page 231 INDEX output display choices 5-65 line 2-1 Output Filters Menu 1 5-68 ratings 2-2 Output Filters Menu 2 5-70, 5-87 Graphical display adjusting Y-axis scale 5-46 Output Offset Ref 1 Menu 5-70 Output Offset Ref 2 Menu 5-72 Auto-Scale 5-46 Reference Channel Menu 5-66, 5-68 cursor keys 5-47 reference channel restrictions 3-1...
  • Page 232 REF OUT connector 4-10 modulation depth control 5-23 Reference channel described 3-8 Oscillator Menu 5-16 Reference channel inputs - 7124 RCU 3-8 output amplitude sweeps - general 3-10 Reference channel inputs - Main Console 3-8 output update rate 3-10 Reference harmonic control 5-6, 5-12, 5-63, 5-64, 5-...
  • Page 233 A-1 choice of number of data bits 6-2 for internal oscillator A-4 choice of parity check option 6-3 for internal oscillator - 7124 RCU A-4 connector 4-7 for internal oscillator - main console A-4 general features 6-2 for measurement modes A-1...
  • Page 234 INDEX TRIG OUT connector 4-8 User setttings 3-18 TRIGOUT [n] command 6-27, F-23 Vector magnitude 3-13 TRIGOUTPOL [n] command 6-27, F-23 VER command 6-33, F-23 TTL REF IN connector 4-7, 4-10 Virtual reference mode Typical Lock-in Amplifier Experiment 5-91 automatic setup 5-58 USB connector 4-6 Configuration Menu 5-61 USB interface...
  • Page 235 This Warranty shall not apply to any instrument or component not manufactured by AMETEK Advanced Measurement Technology, Inc. When products manufactured by others are included AMETEK Advanced Measurement Technology, Inc equipment, the original manufacturers Warranty is extended to AMETEK Advanced Measurement Technology, Inc customers.

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