SRS Labs Lock-In Amplifier manual SR530 with the RS232 Interface, SR530 with the Gpib Interface

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6)Answers are coming back from the SR530 too slowly due to the W6 default setting for the character interval time. Use the W command to speed up the transmission from the SR530. This can cause problems for the GPIB interface if the echo mode is on (switch 6 of SW1).

The SR530 with the RS232

Interface

The RS232 is a popular serial interface standard for bit serial communication. Despite the existence of the standard there are many permutations of control lines, baud rates, and data formats. If you do not have a lot of experience interfacing RS232 equipment you should read Appendix B for a description of the RS232 and interfacing tips.

Data Communications Equipment (DCE)

The SR530 is configured as DCE so that it may be connected directly to a terminal. If the SR530 is to be interfaced with another DCE device, a special cable (sometimes referred to as a 'modem' cable) is required. To use the RS232 interface you must set the switches in SW2 to match your computer's baud rate, parity, and number of stop bits. Refer to Page 7 for details.

Wait Command

The SR530 normally waits until the RS232 'Clear to Send' control line (CTS) is asserted before sending characters. However, some computers do not set and reset the CTS line, possibly causing the SR530 to send data when the computer is not ready to read it. The SR530 may be 'slowed down' using the W command. Sending 'Wn' causes the unit to wait nx4 mS before sending each character over the RS232 bus. The command W0 sets the wait interval to zero and results in the fastest transmission. The wait interval is set to 6 (24 mS)on power-up.

Termination Sequences

The default RS232 termination characters are sufficient to interface with most computers, however, it will occasionally be necessary to send special terminating sequences to fit the requirements of some computers. This can be done with the J command. The format for the

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command is:

J {n1,n2,n3,n4}

where n1, n2, n3, and n4 are decimal values between 0 and 255 corresponding to the ASCII codes of the desired termination characters. For instance, if the desired termination sequence is an asterisk, (ASCII 42), two carriage returns, (ASCII 13), and a line-feed, (ASCII 10), the appropriate command is:

J 42,13,13,10

If a G command is sent requiring an answer of 24 (sensitivity = 500 mV), the SR530 would respond with the string

24*<cr><cr><lf>

Up to four terminating characters may be specified by the J command. If no arguments are sent with the J command, the terminating sequence returns to the default (echo on: <cr><lf>; echo off: <cr>).

The J command does not affect the terminating character (<cr>) required at the end of commands received by the SR530. It also does not affect the terminating sequence sent with data over the GPIB interface.

The SR530 with the GPIB

Interface

For a brief introduction to the GPIB standard, please read Appendix C at the back of this manual. Before using the GPIB interface you must set the switches in SW1 per the instructions on page 7.

GPIB Capabilities

The GPIB capabilities of the SR530 consistent with IEEE standard 488 (1978) are shown in the table below. Also shown are the responses of the SR530 to some standard commands.

Code

Function

SH1

Source handshake capability

AH1

Acceptor handshake capability

T5

Basic Talker, Serial Poll, Unaddressed to

 

talk if addressed to listen

L4

Basic Listener, Unaddressed to listen if

 

addressed to talk

SR1

Service request capability

PP0

No parallel poll capability

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Contents Model SR530 Page Table of Contents Appendix C Gpib Operating NON-OPERATINGPage SR530 Specification Summary Demodulator GpibFront Panel Summary Enbw Abridged Command List Configuration Switches Status Byte DefinitionSR510 Guide to Operation Front Panel Signal InputsSignal Filters SensitivityDisplay Select Dynamic ReserveStatus Channel 1 DisplayRel Channel OutputOutput Channel Offset ChannelExpand Channel Rcosø OutputChannel 2 Display Auto Phase Rsinø Output Reference InputTrigger Level Reference Display Reference ModePhase Controls Time ConstantPower DefaultsLocal and Remote SR530 Guide to Operation Rear Panel Page Communicating with the SR530 Command SyntaxSR530 Guide to Programming Front Panel Status LEDsRS232 Echo and No Echo Operation Try-Out with an Ascii TerminalSR530 Command List LOW Norm HighN1,n2,n3,n4 Page Errors Status ByteBit Common Hardware Problems include ResetTrouble-Shooting Interface Problems Common Software Problems includeSR530 with the RS232 Interface SR530 with the Gpib InterfaceSerial Polls and Service Requests Gpib with RS232 Echo ModeSR530 with Both Interfaces Lock-in Technique Measurement ExampleUnderstanding the Specifications Shielding and Ground LoopsPage Page SR530 Block Diagram Reference Channel Signal ChannelPhase Sensitive Detectors DC Amplifiers and System GainCircuit Description Reference Oscillator Demodulator and Low Pass AmplifierFront Panel Analog Output and ControlExpand Microprocessor ControlPower Supplies RS232 InterfaceGpib Interface Multiplier Adjustments Amplifier and Filter AdjustmentsCalibration and Repair Notch Filters Replacing the Front-End TransistorsAppendix a Noise Sources and Cures Non-Essential Noise SourcesPage Page Baud Rate Case 1 The Simplest ConfigurationAppendix B Introduction to the RS232 Case 2 RS232 with Control LinesVoltage Levels Stop BitsParity Final TipAppendix C Introduction to the Gpib Bus DescriptionAppendix D Program Examples Program Example IBM PC, Basic, via RS232Program Example IBM PC, Microsoft Fortran v3.3, via RS232 Page Program Example IBM PC, Microsoft C v3.0, via RS232 #include stdio.hPage Program Example 4 IBM PC,Microsoft Basic, via Gpib ′INCREMENT X6 Output by 2.5 MV Program Example HP85 via Gpib Documentation SW1 Oscillator Board Parts ListPC1 DpdtBR2 Main Board Parts ListBR1 BT1SR530 Component Parts List SR530 Component Parts List Gpib Shielded 22U MINPIN D CX1CY1 FU1MPSA18 SR530 Component Parts List SR530 Component Parts List SR530 Component Parts List SR530 Component Parts List SR530 Component Parts List SPSTX8 4PDTSR513 Assy SR530 Component Parts List Z80A-CPU Static RAM, I.CMica TIE AnchorTranscover #4 FlatFront Panel Board Parts List RED LD1 LD2LD3 Quad Board Parts List SR530 Component Parts List PC1 SR530 Component Parts List Miscellaneous Parts List SR530 Component Parts List

SR530, Lock-In Amplifier specifications

The SRS Labs Lock-In Amplifier, model SR530, is a powerful tool designed for high-precision measurements in the realm of scientific research and industrial applications. This state-of-the-art instrument excels in extracting small signals from noisy environments, making it an invaluable asset for experiments in fields such as physics, engineering, and materials science.

One of the main features of the SR530 is its ability to perform synchronous detection, which is key to improving signal-to-noise ratios. By utilizing a reference signal, the device correlates the incoming signal with the reference to effectively filter out noise, allowing for the accurate measurement of weak signals that might otherwise be obscured. This process of phase-sensitive detection is fundamental to the operation of the Lock-In Amplifier.

The SR530 offers a wide frequency range, covering from 0.1 Hz to 100 kHz. This broad frequency response allows it to handle a diverse array of signals, making it suitable for various applications including optical detection, capacitance measurements, and in many cases, voltammetry. The device is also equipped with multiple inputs and outputs, facilitating the integration with other laboratory equipment and enabling complex experimental setups.

Precision is further enhanced with its adjustable time constant, which allows users to optimize the response time based on experimental needs. The user can choose time constants from 10 microseconds to 10 seconds, accommodating fast dynamic measurements as well as those requiring stability over longer durations.

Another remarkable characteristic of the SR530 is its digital processing capabilities. The device features a highly accurate digital voltage measurement system, minimizing drift and ensuring long-term stability. Additionally, the use of microprocessors enhances data handling and allows for features such as programmable settings, facilitating automated measurements.

Moreover, the SR530 includes a range of output options, including analog outputs, which can be used for direct signal processing, as well as digital interfaces for integration with computers. This ensures that users can not only capture high-fidelity data but also analyze and display it efficiently.

In conclusion, the SRS Labs SR530 Lock-In Amplifier stands out due to its sophisticated technology, versatile features, and robust performance. Its precision, flexibility, and ease of use make it an ideal choice for researchers and engineers looking to unlock the potential of weak signal measurement in complex environments.
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