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SRS Labs SIM928 Operation And Service Manual

Isolated voltage source
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Operation and Service Manual
Isolated Voltage Source
SIM928
Stanford Research Systems
Revision 2.0
August 25, 2006

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  • Page 1 Operation and Service Manual Isolated Voltage Source SIM928 Stanford Research Systems Revision 2.0 August 25, 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 9-01593-903 SIM928 Isolated Voltage Source...

  • Page 3: Table Of Contents

    Contents General Information Safety and Preparation for Use ....Symbols ......Notation .
  • Page 4 Contents SIM928 Isolated Voltage Source...

  • Page 5: General Information

    Do not install substitute parts or perform any unauthorized modifications to this instrument. The SIM928 is a single-wide module designed to be used inside the SIM900 Mainframe. Do not turn on the power until the module is...

  • 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) SIM928 Isolated Voltage Source...

  • 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 SIM928 are set as straight teletype font, while responses received by the host computer from the SIM928 are set as slanted teletype font.

  • Page 8: Specifications

    24 V) General Characteristics Interface Serial (RS-232) through SIM interface Connectors Banana binding posts ( , , and chassis ground) DB–15 (male) SIM interface Weight 3 lbs Dimensions 1 5 W 3 6 H 7 0 D SIM928 Isolated Voltage Source...

  • Page 9: Getting Started

    1 Getting Started This chapter gives you the necessary information to get started quickly with the SIM928 Isolated Voltage Source. In This Chapter 1.1 Introduction to the Instrument ... . 1 – 2 1.1.1...

  • Page 10: Introduction To The Instrument

    If either battery appears fully discharged, it will be switched onto the internal charger circuit; if both batteries appear discharged (as can occur after an extended storage period), the SIM928 will not be first use after extended storage able to turn on the output stage. In this case, you should allow about 5–6 hours of powered operation to bring the first battery up to full...

  • Page 11: Adjust

    0 V. To reverse the polarity, the key must be released and then re-pressed to resume auto-repeat. Note that the programmed voltage can be modified independent of the on o state of the SIM928. Adjusting the voltage while in the On SIM928 Isolated Voltage Source...

  • Page 12: Battery

    When the programmed voltage V 1 999 V, the display shows the full settable resolution of the SIM928. At greater voltages ( V 1 999 V) the least significant digit shown corresponds to 10 mV. It is still possible to make discrete 1 mV steps using [1 mV ]; by counting key taps, the user can determine the sub-display voltage setting.

  • Page 13: Output

    It is also possible, if a SIM928 is left in storage for several years with- out operation, that the batteries will have lost a significant fraction of their capacity due to aging.

  • Page 14: Sim Interface

    10 mA. If an low-impedance load causes the output current to reach around 15 mA, the output will go into current-limit mode, and the red OVLD indicator will turn on. The SIM928 can remain in over- load indefinitely, and will return to its programmed output voltage as soon as the load current is reduced.

  • Page 15: Direct Interfacing

    RS-232 serial port of a personal computer. Connect RXD from the SIM928 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 16 To interface directly to the DB–9 male (DTE) RS-232 port typically found on contemporary personal computers, a cable must be made with a female DB–15 socket to mate with the SIM928, and a female DB–9 socket to mate with the PC’s serial port. Separate leads from the DB–15 need to go to the power supply, making what is sometimes...

  • Page 17: Remote Operation

    2 Remote Operation This chapter describes operating the SIM928 over the serial interface. In This Chapter 2.1 Index of Common Commands ... . 2 – 2 Alphabetic List of Commands ... . 2 – 4 Introduction .

  • Page 18: Index Of Common Commands

    2 – 13 Overload Status OVSE(?) [i,] j 2 – 13 Overload Status Enable PSTA(?) z 2 – 13 Pulse STATUS Mode Interface *RST 2 – 13 Reset CONS(?) z 2 – 14 Console Mode *IDN? 2 – 14 Identify SIM928 Isolated Voltage Source...
  • Page 19 2 – 14 Operation Complete LEXE? 2 – 14 Execution Error LCME? 2 – 15 Device Error LBTN? 2 – 15 Button TOKN(?) z 2 – 16 Token Mode TERM(?) z 2 – 16 Response Termination SIM928 Isolated Voltage Source...

  • Page 20: Alphabetic List Of Commands

    2 – 9 Output O OPON 2 – 9 Output On OVCR? [i] 2 – 13 Overload Condition OVSE(?) [i,] j 2 – 13 Overload Status Enable OVSR? [i] 2 – 13 Overload Status PARI(?) z 2 – 11 Parity SIM928 Isolated Voltage Source...
  • Page 21 2.2 Alphabetic List of Commands 2 – 5 PSTA(?) z 2 – 13 Pulse STATUS Mode TERM(?) z 2 – 16 Response Termination TOKN(?) z 2 – 16 Token Mode VOLT(?) f 2 – 9 Voltage SIM928 Isolated Voltage Source...

  • Page 22: Introduction

    2 – 6 Remote Operation 2.3 Introduction Remote operation of the SIM928 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 voltage source from a remote computer, either through the SIM900 Mainframe or directly via RS-232 (see Section 1.3.2.1).

  • Page 23: Commands

    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. SIM928 Isolated Voltage Source...

  • Page 24: Notation

    In these examples, all data sent by the host computer to the SIM928 are set as straight teletype font, while responses received the host computer from the SIM928 are set as slanted teletype font. The usage examples vary with respect to set query, optional param- eters, and token formats.

  • Page 25: Output Commands

    (see section 1.2.2.2). In particular, the command will only be operative if one of the batteries is in the “ready” state (see BATS?, below). Furthermore, the SIM928 may delay initiating BCOR by up to 1 s for internal synchronization.

  • Page 26: Serial Communication Commands

    Example: BCOR BATS? Battery State Query the battery status of the SIM928. The response is return in the format: <a>,<b>,<x> where <a>and <b> correspond to batteries “A” and “B”, and are equal to 1 for in use, 2 for charging, and 3 for ready standby.

  • Page 27: Status Commands

    At power-on, the baud rate defaults to 9600. Actual baud rate settings depend on implementation details of the SIM928, based on modulo prescalars of the 10 MHz system clock. As a result, queries of BAUD? will in general be slightly di erent from the set values.
  • Page 28 Upon executing a CESR? query, the returned bit(s) of the CESR register are cleared. Example: CESR? CESE(?) [i,] j Communication Error Status Enable Set (query) Communication Error Status Enable Register [bit i] to j . Example: CESE? SIM928 Isolated Voltage Source...

  • Page 29: Interface Commands

    STATUS low until a *STB? query is received. At power-on, PSTA is set to OFF. Example: PSTA? 2.4.8 Interface commands *RST Reset Reset the SIM928 to default configuration. The following commands are internally executed upon *RST: VOLT 0 EXON OFF Example: *RST SIM928 Isolated Voltage Source...
  • Page 30 No execution error since last LEXE? Illegal value Wrong token Invalid bit 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. SIM928 Isolated Voltage Source...
  • Page 31 Query the last button-press code. Valid codes are: Value Definition no button pressed since last LBTN? [On O ] [100 mV ] [100 mV ] [10 mV ] [10 mV ] [1 mV ] [1 mV ] [Battery Override] Example: LBTN? SIM928 Isolated Voltage Source...
  • Page 32 Token Mode Set (query) the Token Query mode to z (OFF 0, ON 1) . If TOKN ON is set, then queries to the SIM928 that return tokens will return the text keyword; otherwise they return the decimal integer value.

  • Page 33: Status Model

    The SIM928 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 SIM928 status model: Condition Registers : These read-only registers correspond to the real-time condi- tion of some underlying physical property being monitored.

  • Page 34: Status Byte (Sb)

    Remote Operation 2.5.1 Status Byte (SB) The Status Byte is the top-level summary of the SIM928 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 35: Service Request Enable (Sre)

    Input Bu er. QYE : Query Error. Indicates data in the Output Queue has been lost. DDE : Device Dependent Error. Indicates a SIM928 had a delayed execution error, due to an illegal mode state. The error code can be queried with LDDE?.

  • Page 36: Standard Event Status Enable (Ese)

    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 SIM928. Command Error. Indicates a parser- detected error. CTSH : Undefined for the SIM928.

  • Page 37: Communication Error Status Enable (Cese)

    2.5.7 Overload Status (OVCR) The Overload Condition Register consists of 3 single-bit monitors of conditions within the SIM928. 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 38: Overload Status Enable (Ovse)

    The OVSE acts as a bitwise AND with the OVSR register to produce the single bit OVSB message in the Status Byte Register (SB). It can be set and queried with the OVSE(?) command. This register is cleared at power-on. SIM928 Isolated Voltage Source...
  • Page 39 3 Parts Lists and Schematics This chapter presents a brief description of the SIM928 circuit design. A complete parts list and circuit schematics are included. In This Chapter 3.1 Circuit Description ....3 – 2 3.1.1...

  • Page 40: Circuitry

    3.1.2 Battery charger The SIM928 battery pack contains two identical 25.2 V NiMH batter- ies. During normal operation at least one battery is connected at any time to the isolated voltage regulator circuit. The other battery is either idle (disconnected) or connected to the charger circuit.
  • Page 41 NiMH bat- teries are best operated at temperatures close to room temperature. The SIM928 power dissipation and the thermal environment of the SIM900 Mainframe will lead to a temperature rise of the batteries which is slightly above room temperature.
  • Page 42 SIM900 mainframe can reduce maximum temperatures by spreading out modules with higher power dissipation like the SIM928 evenly over the mainframe slots. In any case the e ects on actual lifetime should be small. 3.1.2.3 Battery voltage monitoring While the battery is connected to the charger circuit, its cathode is referenced to 15 V.

  • Page 43: Battery Pack

    3.1 Circuit Description 3 – 5 SIM928 can be forced to switch in a fresh battery (see section 1.2.2.2) prior to connecting to the sensitive user system. A fully charged, unloaded battery has a terminal voltage several volts higher than that of a loaded, almost fully discharged battery. During switch-over both batteries are connected to the isolated user regulator for approx.

  • Page 44: Display And Buttons

    3.1.5 Display and buttons The SIM928 display is fully static to minimize noise. Display and LEDs are driven and buttons are read by shift registers which hold their state without firmware update. The microcontroller only reads from and writes to these registers when display updates are necessary or the user presses one of the buttons.

  • Page 45: Parts List

    U604 3-01370 OPA277UA Q202-Q205,Q601,Q608, 3-01150 FZT658 R603,R604,R647 4-01443 33 U606 3-01161 OPA336N Q610 R613 4-01467 330 U607 3-01162 OPA244N Q207,Q208,Q613 3-00927 MMBT2907 R614,R616 4-01491 3.3K Y101 6-00571 10.000MHz 3.3 Schematic Diagrams Schematic diagrams follow this page. SIM928 Isolated Voltage Source...

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