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SRS Labs SIM980 Operation And Service Manual

Analog summing amplifier
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Operation and Service Manual
Analog Summing Amplifier
SIM980
Stanford Research Systems
Revision 1.9
August 28, 2006

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  • Page 1 Operation and Service Manual Analog Summing Amplifier SIM980 Stanford Research Systems Revision 1.9 August 28, 2006...
  • Page 2 Copyright c Stanford Research Systems, Inc., 2005, 2006. All rights reserved. Stanford Research Systems, Inc. 1290–D Reamwood Avenue Sunnyvale, CA 94089 USA Phone: (408) 744-9040 Fax: (408) 744-9049 www.thinkSRS.com e-mail: info@thinkSRS.com Printed in U.S.A. Document number 9-01591-903 SIM980 Analog Summing Amplifier...

  • Page 3: Table Of Contents

    Other tests and adjustments ....3 – 6 SIM980 Performance Test Record ... . 3 – 7 4 Circuitry 4 –...
  • Page 4 Contents SIM980 Analog Summing Amplifier...

  • Page 5: General Information

    Do not install substitute parts or perform any unauthorized modifi- cations to this instrument. The SIM980 is a single-wide module designed to be used inside the SIM900 Mainframe. Do not turn on the power until the module is completely inserted into the mainframe and locked in place.

  • Page 6: Symbols

    Symbols you may Find on SRS Products Symbol Description Alternating current Caution - risk of electric shock Frame or chassis terminal Caution - refer to accompanying documents Earth (ground) terminal Battery Fuse On (supply) Off (supply) SIM980 Analog Summing Amplifier...

  • Page 7: Notation

    Literal text other than command names is set as OFF. Remote command examples will all be set in monospaced font. In these examples, data sent by the host computer to the SIM980 are set as straight teletype font, while responses received by the host computer from the SIM980 are set as slanted teletype font.

  • Page 8: Specifications

    5 V (100 mA) 15 V (300 mA) General Characteristics Interface Serial (RS-232) through SIM interface Connectors BNC (5 front, 1 rear) DB–15 (male) SIM interface Weight 1.5 lbs Dimensions 1 5 W 3 6 H 7 0 D SIM980 Analog Summing Amplifier...

  • Page 9: Getting Started

    1 Getting Started This chapter gives you the necessary information to get started quickly with the SIM980 Summing Amplifier. In This Chapter 1.1 Introduction to the Instrument ... . 1 – 2 1.1.1...

  • Page 10: Introduction To The Instrument

    DC to 1 MHz. 1.1.1 Overview The basic function of the SIM980 is to add or subtract up to four analog signals. Each input channel can be separately configured for inverting or non-inverting operation, or switched o . Each input is and DC-coupled, and accepts signals between 10 V.

  • Page 11: Inputs

    1.2 Front-Panel Operation 1 – 3 1.2.1 Inputs Each of the four input channels of the SIM980 has a front-panel block consisting of the BNC input connector, a control button, and several LED indicators. 1.2.1.1 Polarity toggle Each input can be switched between inverting or non-inverting po- larity by briefly pressing that channel’s control button.

  • Page 12: Sim Interface

    SIM900 Mainframe via this connection, either through one of the internal Mainframe slots, or the remote cable interface. It is also possible to operate the SIM980 directly, without using the SIM900 Mainframe. This section provides details on the interface.
  • Page 13 RS-232 serial port of a personal computer. Connect RXD from the SIM980 directly to RD on the PC, TXD directly to TD, and similarly RTS RTS and CTS CTS. In other words, a null-modem style cable is not needed.
  • Page 14 DB–15 F to SIM980 Name DB–9 F Computer Ground to P S 15 VDC 5 VDC 15 VDC Ground (P S return current) Signal Ground (separate wire to Ground) Table 1.2: SIM980 Direct Interface Cable Pin Assignments SIM980 Analog Summing Amplifier...

  • Page 15: Remote Operation

    2 Remote Operation This chapter describes operating the SIM980 over the serial interface. In This Chapter 2.1 Index of Common Commands ... . 2 – 2 Alphabetic List of Commands ... . 2 – 4 Introduction .

  • Page 16: Index Of Common Commands

    Interface *RST 2 – 13 Reset *IDN? 2 – 14 Identify *OPC(?) 2 – 14 Operation Complete CONS(?) z 2 – 14 Console Mode LEXE? 2 – 14 Execution Error LCME? 2 – 15 Command Error SIM980 Analog Summing Amplifier...
  • Page 17 2.1 Index of Common Commands 2 – 3 LBTN? 2 – 15 Button TOKN(?) z 2 – 15 Token Mode TERM(?) z 2 – 16 Response Termination SIM980 Analog Summing Amplifier...

  • Page 18: Alphabetic List Of Commands

    2 – 13 Overload Status Enable OVSR? [i] 2 – 13 Overload Status PARI(?) z 2 – 11 Parity PSTA(?) z 2 – 13 Pulse STATUS Mode READ? [i] 2 – 9 Read O set Voltage SIM980 Analog Summing Amplifier...
  • Page 19 2.2 Alphabetic List of Commands 2 – 5 TERM(?) z 2 – 16 Response Termination TOKN(?) z 2 – 15 Token Mode SIM980 Analog Summing Amplifier...

  • Page 20: Introduction

    2 – 6 Remote Operation 2.3 Introduction Remote operation of the SIM980 is through a simple command lan- guage documented in this chapter. Both set and query forms of most commands are supported, allowing the user complete control of the summing amplifier from a remote computer, either through the SIM900 Mainframe or directly via RS-232 (see Section 1.3.2.1).

  • Page 21: Command Syntax

    CR LF , the following two commands are equivalent: TERM CRLF —or— TERM 3 For queries that return token values, the return format (keyword or integer) is specified with the TOKN command. SIM980 Analog Summing Amplifier...

  • Page 22: Notation

    In these examples, all data sent by the host computer to the SIM980 are set as straight teletype font, while responses received the host computer from the SIM980 are set as slanted teletype font. The usage examples vary with respect to set query, optional param- eters, and token formats.

  • Page 23: Amplifier Commands

    Query the output voltage, in tenths of microvolts. When the o set autocalibration circuitry is active, an internal high- gain amplifier is activated to monitor the SIM980 output. This signal is digitized by an internal analog-to-digital converter. The READ? query allows the user to directly record this measurement. When READ? is queried, the high-gain amplifier is turned on.

  • Page 24: Autocalibration Commands

    1), the armed flag is set without testing. The o set autocalibration proceedure requires that all inputs to the SIM980 be at 0 V (that is, either open or shorted to ground). The ARMC command performs a test of all 4 channels to ensure that each input is less than 500 V amplitude.

  • Page 25: Serial Communication Commands

    Example: PARI EVEN 2.4.7 Status Commands The Status commands query and configure registers associated with status reporting of the SIM980. *STB? [i] Status Byte Reads the Status Byte register [bit i]. Execution of the *STB? query (without the optinal bit i) always causes the STATUS signal to be deasserted.
  • Page 26 Example: CESR? CESE(?) [i,] j Comm Error Status Enable Set (query) Comm Error Status Enable Register [for bit i] to j Example: CESE? OVCR? [i] Overload Condition Query Overload Condition Register [for bit i]. Example: OVCR? SIM980 Analog Summing Amplifier...

  • Page 27: Interface Commands

    Example: PSTA? 2.4.8 Interface Commands Interface commands provide generic control over the interface be- tween the SIM980 and the host computer. *RST Reset Reset the SIM980 to default configuration. After *RST, all channels are set to positive polarity, and to o . This is equivalent to the following command sequence: CHAN 0,1;...
  • Page 28 No execution error since last LEXE? Illegal value Wrong token Invalid bit Autocalibration not armed Example: *STB? 12; LEXE?; LEXE? The error (3, “Invalid bit,”) is because *STB? only allows bit-specific queries of 0–7. The second read of LEXE? returns 0. SIM980 Analog Summing Amplifier...
  • Page 29 Thus, the only possible responses to the TOKN? query are ON and 0. On reset, TOKN is set to OFF. Example: TOKN OFF SIM980 Analog Summing Amplifier...
  • Page 30 LFCR 4) . The term sequence is appended to all query responses sent by the module, and is constructed of ASCII character(s) 13 (car- riage return) and 10 (line feed). The token mnemonic gives the sequence of characters. At power-on, TERM is set to CRLF. Example: TERM? SIM980 Analog Summing Amplifier...

  • Page 31: Status Model

    The SIM980 status registers follow the hierarchical IEEE–488.2 for- mat. A block diagram of the status register array is given in Figure 2.1. There are three categories of registers in the SIM980 status model: Condition Registers : These read-only registers correspond to the real-time condi- tion of some underlying physical property being monitored.

  • Page 32: Status Byte (Sb)

    Remote Operation 2.5.1 Status Byte (SB) The Status Byte is the top-level summary of the SIM980 status model. When masked by the Service Request Enable register, a bit set in the Status Byte causes the STATUS signal to be asserted on the rear- panel SIM interface connector.

  • Page 33: Service Request Enable (Sre)

    Input Bu er. QYE : Query Error. Indicates data in the Output Queue has been lost. DDE : Device Dependent Error. This bit is undefined in the SIM980. EXE : Execution Error. Indicates an error in a command that was successfully parsed.

  • Page 34: Communication Error Status (Cesr)

    OVR : Input Bu er Overrun. Set when the Input Bu er is overrun by incoming data. Causes the Input Bu er to be flushed, and resets the command parser. RTSH : Undefined for the SIM980. Command Error. Indicates a parser- detected error. CTSH : Undefined for the SIM980.

  • Page 35: Overload Status (Ovcr)

    2.5.7 Overload Status (OVCR) The Overload Condition Register consists of 5 single-bit monitors of conditions within the SIM980. Bits in the OVCR reflect the real-time values of their corresponding signals. Reading the entire register, or individual bits within it, does not a ect the OVCR.
  • Page 36 2 – 22 Remote Operation SIM980 Analog Summing Amplifier...

  • Page 37: Performance Tests

    Other tests and adjustments ... . . 3 – 6 SIM980 Performance Test Record ..3 – 7 3 – 1...

  • Page 38: Introduction

    3 – 2 Performance Tests 3.1 Introduction Under typical usage, only the internal autocalibration cycle is needed to keep the SIM980 operating within specifications (see sec- tion 1.2.1.3). If further adjustment is needed, this section describes the procedure. 3.2 Tools and preparation The necessary tools for a complete recalibration are: a small flat-head screwdriver...

  • Page 39: Calibration Words

    3.3 Precalibration Values 3 – 3 3.3.2 Calibration Words Next, query the SIM980 over the remote interface to determine the calibration word values. Send the remote queries: OFST? 1 . . . OFST? 6 and record the results. 3.3.3 DC Gain Match Set the DC voltage source to 2 V.

  • Page 40: Calibration

    CHAN 0,0 OFST 5, 128; OFST 6, 127 which set the electronic trim-DAC outputs to midpoint. Connect the SIM980 output to the voltmeter, and adjust R245 to zero the voltage reading. After nulling R245, an unconditional autocalibration cycle should be initiated.

  • Page 41: Dc Gain Calibration

    3.4 Calibration 3 – 5 3.4.2 DC Gain Calibration All resistors of the SIM980 gain network have a precision of 0.1%. Any two channels can therefore di er in their gain by up to 0.2%. Gain between polarity settings can also di er by 0.2%. The common mode rejection of two channels set to take the di erence of two signals is therefore limited to 0.2% or approximately 54 dB...

  • Page 42: Other Tests And Adjustments

    3.5 Other tests and adjustments The SIM980 internally generates two precision power supply volt- ages for the input bu er amplifiers. These 13 0 V and 13 0 V volt- ages can be tested at test points TP401 ( 13 0 V), TP402 ( 13 0 V) and TP403 (ground).

  • Page 43: Sim980 Performance Test Record

    3.6 SIM980 Performance Test Record 3 – 7 3.6 SIM980 Performance Test Record This page should be photocopied to record results. General Name: Serial Number: Date Time: O set Voltage Output: Channel 1: Channel 2: Channel 3: Channel 4: Calibration Words...
  • Page 44 3 – 8 Performance Tests SIM980 Analog Summing Amplifier...
  • Page 45 4 Parts Lists and Schematics This chapter presents a brief description of the SIM980 circuit design. A complete parts list and circuit schematics are included. In This Chapter 4.1 Circuit Descriptions ....4 – 2 4.1.1...

  • Page 46: Circuitry

    (baluns) to reduce conducted EMI (electromagnetic interference) of RF noise currents on the shield of BNC cables attached to the module. For the same reason the BNCs are isolated from the SIM980’s front and back panels. This design ensures the best DC and low frequency performance in noisy environments.

  • Page 47: O Set Measurement & Control

    BNC shell. The opamp bu er combination U210 U211 does not by itself satisfy the o set voltage specifications of the SIM980. O set voltage stabil- ity is therefore guaranteed by U212, a di erential integrator which drives a di erential current source, QN201A B, to trim the input o set voltage of U210.

  • Page 48: Parts Lists

    U210 3-01278 AD829AR R299,R2101 U211 3-01247 BUF634F R106,R262,R263 4-01431 U212 3-00998 OPA277UA R107-R110,R115 U401 4-01519 3-01415 LP2951CMM R112,R113, R421,R422 4-01551 U402 1.0M 3-01248 LT1175CN8 R114,R120,R121, U403 4-01503 3-01279 MAX5258 R409-R414,R424 U404 3-01280 LTC2050CS5 U405 3-01367 DG419DY SIM980 Analog Summing Amplifier...

  • Page 49: Schematic Diagrams

    4.3 Schematic Diagrams 4 – 5 4.3 Schematic Diagrams Schematic diagrams follow this page. SIM980 Analog Summing Amplifier...

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