SRS Labs SIM964 Operation And Service Manual

Operation and Service Manual

Stanford Research Systems

Analog Limiter

SIM964

Revision 1.4 • August 28, 2006

Certification

Stanford Research Systems certifies that this product met its published specifications at the time
of shipment.

Warranty

This Stanford Research Systems product is warranted against defects in materials and workman­ship for a period of one (1) year from the date of shipment.

Service

For warranty service or repair, this product must be returned to a Stanford Research Systems
authorized service facility. Contact Stanford Research Systems or an authorized representative
before returning this product for repair.

Information in this document is subject to change without notice.

Copyrightc Stanford Research Systems, Inc., 2006. All rights reserved.

Stanford Research Systems, Inc.
1290–D Reamwood Avenue
Sunnyvale, CA 94089 USA
Phone: [phone] • Fax: [phone]

www.thinkSRS.com • e-mail: [e-mail]

Printed in U.S.A. Document number 9-01599-903

SIM964 Analog Limiter

Contents

General Information iii

Safety and Preparation for Use . . . . . . . . . . . . . . . . iii

Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv

Notation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . vi

1 Getting Started 1 – 1

1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 1– 2

1.2 Front-panel Operation . . . . . . . . . . . . . . . . . . 1 –3

1.3 Clock Stopping . . . . . . . . . . . . . . . . . . . . . . 1 –5

1.4 SIM Interface . . . . . . . . . . . . . . . . . . . . . . . . 1 – 6

2 Remote Operation 2 – 1

2.1 Index of Common Commands . . . . . . . . . . . . . . 2 – 2

2.2 Alphabetic List of Commands . . . . . . . . . . . . . . 2– 4

2.3 Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2– 5

2.4 Commands . . . . . . . . . . . . . . . . . . . . . . . . . 2 – 5

2.5 Status Model . . . . . . . . . . . . . . . . . . . . . . . . 2 – 15

3 Circuitry 3 – 1

3.1 Circuit Descriptions . . . . . . . . . . . . . . . . . . . . 3– 2

3.2 Parts Lists . . . . . . . . . . . . . . . . . . . . . . . . . 3 – 5

3.3 Schematic Diagrams . . . . . . . . . . . . . . . . . . . 3 – 6

i

ii Contents

SIM964 Analog Limiter

General Information

The SIM964 Analog Limiter, part of Stanford Research Systems’
Small Instrumentation Modules family, is a low-noise programmable
clamp for general signal conditioning from DC to 1 MHz. Upper and
lower limits are independently settable between ±10 V with 10 mV
resolution. The clamped signal is available at the front-panel output,
while rear-panel logic outputs indicate when either limit is exceeded.

Safety and Preparation for Use

The front-panel input, front-panel output, and the rear-panel output
coaxial (BNC) connectors in the SIM964 are referenced to the Earth,
and their outer casings are grounded. No dangerous voltages are
generated by the module.

WARNING

Do not exceed ±15 volts to the Earth at the center terminal of any BNC
connector. Do not install substitute parts or perform any unauthorized

modifications to this instrument.

The SIM964 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.

iii

iv General Information

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)

Symbols you may Find on SRS Products

SIM964 Analog Limiter

General Information v

Notation

The following notation will be used throughout this manual.

WARNING

CAUTION

A warning means that injury or death is possible if the instructions
are not obeyed.

A caution means that damage to the instrument or other equipment
is possible.

Typesetting conventions used in this manual are:

• Front-panel buttons are set as [Button];
[Adjust ] is shorthand for “[Adjust ] & [Adjust ]”.

• Front-panel indicators are set as Overload.

• Remote command names are set as *IDN?.

• 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 SIM964 are set
as straight teletype font, while responses received by the host
computer from the SIM964 are set as slanted teletype font.

SIM964 Analog Limiter

vi General Information

Specifications

Performance Characteristics

Limit setting range ±10 V

Resolution 10 mV

Bandwidth 1 MHz

Gain 1×

Input impedance 1 MΩ

Output noise < 400 µV rms

Total harmonic distortion 0.01 % (−80 dB) at 1 kHz

Slew rate 70 V/µs

Limit detection TTL level outputs are  when

corresponding limit (upper/lower) is exceeded.

Operating temperature 0◦C to 40◦C, non-condensing

Power +5 V (50 mA typ., 100 mA max.)

±15 V (50 mA typ., 300 mA max.)

General Characteristics

Interface Serial (RS-232) through SIM interface

Connectors BNC (2 front, 2 rear)

DB–15 (male) SIM interface

Weight 1.5 lbs

Dimensions 1.500W × 3.600H × 7.000D

SIM964 Analog Limiter

1 Getting Started

In This Chapter

This chapter gives you the necessary information to get started
quickly with the SIM964 Analog Limiter.

1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . 1 – 2

1.2 Front-panel Operation . . . . . . . . . . . . . . . . . 1 – 3

1.2.1 Upper limit . . . . . . . . . . . . . . . . . . . 1 – 3

1.2.2 Lower limit . . . . . . . . . . . . . . . . . . . 1 – 3

1.2.3 Shortcuts . . . . . . . . . . . . . . . . . . . . . 1 – 4

1.2.4 Input . . . . . . . . . . . . . . . . . . . . . . . 1 – 4

1.2.5 Output . . . . . . . . . . . . . . . . . . . . . . 1 – 4

1.2.6 Rear panel outputs . . . . . . . . . . . . . . . 1 – 4

1.3 Clock Stopping . . . . . . . . . . . . . . . . . . . . . 1 – 5

1.4 SIM Interface . . . . . . . . . . . . . . . . . . . . . . 1 – 6

1.4.1 SIM interface connector . . . . . . . . . . . . 1 – 6

1.4.2 Direct interfacing . . . . . . . . . . . . . . . . 1 – 6

1 – 1

1 – 2 Getting Started

1.1 Overview

The SIM964 Analog Limiter is a digitally programmable signal lim­iter with a fully analog signal path. User-defined upper and lower
voltage limits, in the range of ±10 V, define a linear operating band
for input signals from DC to 1 MHz.

The user can select an upper voltage limit, VUL, and a lower voltage
limit, VLL, either remotely, or from the front panel. While the input
signal, Vi, is within the range defined by the upper and lower limits,
the SIM964 output, Vo, is a unity-gain buffered signal that follows the
input signal. If the input signal exceeds one of the limits, the output
of the SIM964 will be clamped to that limit for as long as the signal
is in excess of the limit. When the input signal returns to the range
between the limits, the output immediately recovers and follows the
input signal again.

Mathematically, this can be expressed as





V

UL

V

i

V

LL

Vi> V

UL

VUL≥ Vi≥ V
Vi< V

LL

LL

Vo=















The input and output signals are applied to the SIM964 through
BNC connections on the front panel. Two TTL monitor outputs,
corresponding to upper and lower limit saturation conditions, are
provided through rear-panel BNC connections. The TTL output
level is +5 V when the corresponding limit is not exceeded, and falls
to 0 V for as long as the input is in excess of the limit.

SIM964 Analog Limiter

1.2 Front-panel Operation 1 – 3

1.2 Front-panel Operation

The front panel of the SIM964 (see Figure 1.1) provides a simple
operator interface.

1.2.1 Upper limit

1.2.2 Lower limit

Figure 1.1: The SIM964 front and rear panels.

The [ ] and [ ] buttons on the left side of the front panel are associated
with the upper numeric display to form the Upper Limit block. The
numeric display indicates the value of VUL(in volts), with 10 mV
resolution.

Pressing [UL ] will raise the upper voltage limit, while [UL ] will
lower it. Short presses of either key will step the limit in 10 mV
increments; holding the key continuously will cause the limit setting
to continuously change upwards or downwards at an accelerating
rate.

The upper limit voltage VULcan be set within the range:

+10 V ≥ VUL≥ (VLL+ 100 mV)

The [ ] and [ ] buttons on the right side of the front panel are associ­ated with the lower numeric display to form the Lower Limit block.

SIM964 Analog Limiter

1 – 4 Getting Started

Operation is analogous to the Upper Limit block. Note, however,
that pressing [LL ] will increase the signed value of VLL(that is,
make VLLmore positive); this acts to narrow the linear range of the
SIM964, rather than expand it.

The lower limit voltage VLLcan be set within the range:

(VUL− 100 mV) ≥ VLL≥ −10 V

1.2.3 Shortcuts

Pressing the two buttons [UL ] simultaneously will step the VULset­ting between +10 V, +5 V, 0 V, and −5 V (each successive two-button
press steps to the next setting). This shortcut, however, cannot set
VUL< (VLL+ 100 mV). Similarly, pressing the two buttons [LL
simultaneously will step the VLLsetting between −10 V, −5 V, 0 V,
and +5 V.

1.2.4 Input

The user signal, Vi, is input at the front-panel upper BNC connector,
which presents a 1 MΩ input impedance.

]

1.2.5 Output

1.2.6 Rear panel outputs

The analog output, Vo, is available at the front-panel lower BNC
connector. Note that the SIM964 has a 50 Ω output impedance. When
driving an external 50 Ω user load, this will result in the output signal
being divided by 2.

The two BNC connectors on the rear panel provide TTL monitor
signals for the state of the SIM964 Analog Limiter. When the upper
or lower limit is exceeded, the corresponding rear panel output is
 (0 V); otherwise it idles  (+5 V).

SIM964 Analog Limiter

1.3 Clock Stopping 1 – 5

1.3 Clock Stopping

The microprocessor clock of the SIM964 stops if the module is idle,
“freezing” the digital circuitry. The following actions “wake up” the
clock:

1. A power-on.

2. A press of a front-panel button.

3. Activity (send or receive) at the remote interface.

4. An input overload.

5. An upper or lower limit clamp.

The clock runs for as long as is necessary to complete a limit setting
adjustment, or to communicate the output of a query through the
remote interface. However, the clock will remain active for as long
as the overload or limit condition exists.

This default behavior can be modified with the remote com-

mand AWAK. Setting AWAKON will prevent the clock from stopping.
The module returns to AWAKOFF upon power-on.

SIM964 Analog Limiter