Stanford Research Systems SIM984 Operation manual

Operation and Service Manual
Isolation Amplifier
SIM984
Stanford Research Systems
Revision 1.13 •March 11, 2013
Distribution in the UK & Ireland
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Characterisation,
Measurement &
Analysis

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 workman-
ship 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.
Copyright c Stanford Research Systems, Inc., 2013. All rights reserved.
Stanford Research Systems, Inc.
1290–D Reamwood Avenue
Sunnyvale, CA 94089 USA
Phone: [phone] •Fax: [phone]
www.thinkSRS.com •e-mail: [email protected]
Printed in U.S.A. Document number 9-01691-903
SIM984 Isolation Amplifier

Contents
General Information iii
Symbols ............................. iv
Notation ............................. v
Specifications .......................... vi
1 Getting Started 1 – 1
1.1 Introduction to the Instrument ............. 1–2
1.2 Front-Panel Operation .................. 1–2
1.3 SIM Interface ........................ 1–4
2 Remote Operation 2 – 1
2.1 Index of Common Commands .............. 2–2
2.2 Alphabetic List of Commands .............. 2–3
2.3 Introduction ........................ 2–4
2.4 Commands ......................... 2–4
2.5 Status Model ........................ 2–13
3 Circuitry 3 – 1
3.1 Circuit Descriptions .................... 3–2
3.2 Schematic Diagrams ................... 3–3
i

ii Contents
SIM984 Isolation Amplifier

General Information
The SIM984 Isolation Amplifier, part of Stanford Research Systems’
Small Instrumentation Modules family, is a wide bandwidth, low
noise isolation amplifier for use with analog signals from DC to
1 MHz.
Service
Do not install substitute parts or perform any unauthorized modifi-
cations to this instrument.
The SIM984 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
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)
SIM984 Isolation Amplifier

General Information v
Notation
The following notation will be used throughout this manual.
A warning means that injury or death is possible if the instructions
WARNING are not obeyed.
A caution means that damage to the instrument or other equipment
CAUTION is possible.
Typesetting conventions used in this manual are:
•Front-panel buttons are set as [Button].
•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 SIM984 are set
as straight teletype font, while responses received by the host
computer from the SIM984 are set as slanted teletype font.
SIM984 Isolation Amplifier

vi General Information
Specifications
Performance Characteristics
Isolation voltage ±1000 V (max)
Leakage current <2μA at 1000 Vdc
Isolation capacitance 1000 pF
Isolation Mode Rejection Ratio (IMRR) 150 dB at DC
Maximum input ±10 V
Input impedance 1MΩ
Input noise (typ.) 15 nV/√Hz @ 1 kHz
Input offset drift 3μV/◦C (typ.)
Output voltage range ±10 V
Output current ±20 mA (max.)
Output resistance 50 Ω
Output offset ±0.1 V, adjustable
Output offset drift 1mV/◦C (typ.)
Output noise (typ.) 80 μVrms (100 Hz bandwidth)
200 μVrms (10 kHz bandwidth)
1.5 mVrms (1 MHz bandwidth)
Gain ×1, ×10, ×100
Gain accuracy ±0.5%
THD 0.005% (1 kHz, 600 Ωload)
Frequency range DC to 100 Hz (low BW)
DC to 10 kHz (medium BW)
DC to 1 MHZ (high BW)
Output Slew rate 25 V/μs (Vout =20 Vpp)
Operating temperature 0 ◦Cto40◦C, non-condensing
Power +5 V (100 mA)
±15 V (300 mA)
+24 V (100 mA)
General Characteristics
Interface Serial (RS-232) through SIM interface
Connectors banana jack (2 front)
BNC (1 front, 1 rear)
DB–15 (male) SIM interface
Weight 1.5 lbs
Dimensions 1.5 W×3.6 H×7.0 D
SIM984 Isolation Amplifier

1 Getting Started
This chapter gives you the necessary information to get started
quickly with the SIM984 Isolation Amplifier.
In This Chapter
1.1 Introduction to the Instrument ............. 1–2
1.1.1 Overview ..................... 1–2
1.1.2 Power-on State .................. 1–2
1.2 Front-Panel Operation .................. 1–2
1.2.1 Inputs ....................... 1–2
1.2.2 Gain ........................ 1–2
1.2.3 Bandwidth ..................... 1–3
1.2.4 Output ....................... 1–3
1.3 SIM Interface ....................... 1–4
1.3.1 SIM interface connector ............. 1–4
1.3.2 Direct interfacing ................. 1–5
1–1

1–2 Getting Started
1.1 Introduction to the Instrument
The SIM984 Isolation Amplifier is a low-noise, programmable gain
amplifier for isolating analog signals from DC to 1 MHz.
1.1.1 Overview
The basic function of the SIM984 is to isolate and (possibly) amplify
an analog signal. The input presents a 1 MΩimpedance between the
red and black banana jacks, but is high impedance (floating) between
each input jack and chassis ground. A maximum of ±1000 Vdc can be
between either jack and ground, but the potential between the input
jacks must be less than ±10 V. The input is DC coupled.
A gain of ×1, ×10, or ×100 can be set from the front panel. The output
bandwidth is also adjustable from the front panel, with three choices
of high-frequency cut-off: 100 Hz, 10 kHz, and 1 MHz. Finally, the
output DC offset can be trimmed using a thin screwdriver accessing
the “Offset” hole near the output BNC.
1.1.2 Power-on State
The SIM984 stores its operation state (gain and bandwidth configu-
ration) in non-volatile memory. At power-on, the SIM984 will return
to its previous configuration after a brief system check and initializa-
tion.
1.2 Front-Panel Operation
The front panel of the SIM984 (see Figure 1.1) provides a simple
operator interface.
1.2.1 Inputs
The input to the SIM984 is through the red and black banana jacks in
the front-panel “INPUT” block.
The banana jacks are isolated from the chassis for use with insulated
test leads. If the user connects a BNC–to–Banana adaptor to the
SIM984 to allow inputs from a BNC-terminated cable, it is critical
that no dangerous voltages be applied to the cable, as the exposed
shield of the input BNC could create an electrical hazard.
WARNING
1.2.2 Gain
User gain settings of ×1, ×10, and ×100, are selected with the left and
right [Gain] buttons.
SIM984 Isolation Amplifier

1.2 Front-Panel Operation 1–3
Figure 1.1: The SIM984 front and rear panels.
1.2.3 Bandwidth
User bandwidth settings of DC–100 Hz, DC–10 kHz, and DC–1 MHz
are with the left and right [Bandwidth] buttons.
1.2.4 Output
The amplified, band-limited signal appears at the (ground-referenced)
BNC connectors on the front and rear panels. Each output connec-
tion is through a 50 Ωresistor. For normal operation, the user should
not need to terminate the output. If a 50 Ωtermination is applied,
the output signal will be divided in half.
If the output signal exceeds ±10 V, the output overload detection is
activated. This is indicated by the red OVLD near the top of the
“OUTPUT” block on the front panel.
The SIM984 output offset voltage may be trimmed by adjusting the
SIM984 Isolation Amplifier

1–4 Getting Started
output offset through the front-panel access hole in the “OUTPUT”
block.
1.3 SIM Interface
The primary connection to the SIM984 Isolation Amplifier is the rear-
panel DB–15 SIM interface connector. Typically, the SIM984 is mated
to a 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 SIM984 directly, without using the
SIM900 Mainframe. This section provides details on the interface.
The SIM984 has no internal protection against reverse polarity, missing
CAUTION supply, or overvoltage on the power supply pins. Misapplication of power
may cause circuit damage. SRS recommends using the SIM984 together
with the SIM900 Mainframe for most applications.
1.3.1 SIM interface connector
The DB–15 SIM interface connector carries all the power and commu-
nications lines to the instrument. The connector signals are specified
in Table 1.1
Direction
Pin Signal Src ⇒Dest Description
1 SIGNAL GND MF ⇒SIM Ground reference for signal
2−STATUS SIM ⇒MF Status/service request (GND =asserted, +5V=idle)
3RTS MF ⇒SIM HW handshake (not used in SIM984)
4CTS SIM ⇒MF HW handshake (not used in SIM984)
5−REF 10MHZ MF ⇒SIM 10 MHz reference (no connection in SIM984)
6−5V MF ⇒SIM Power supply (no connection in SIM984)
7−15 V MF ⇒SIM Power supply
8PS RTN MF ⇒SIM Power supply return
9CHASSIS GND Chassis ground
10 TXD MF ⇒SIM Async data (start bit =“0”=+5 V; “1” =GND)
11 RXD SIM ⇒MF Async data (start bit =“0”=+5 V; “1” =GND)
12 +REF 10MHz MF ⇒SIM 10 MHz reference (no connection in SIM984)
13 +5V MF ⇒SIM Power supply
14 +15 V MF ⇒SIM Power supply
15 +24 V MF ⇒SIM Power supply
Table 1.1: SIM Interface Connector Pin Assignments, DB-15
SIM984 Isolation Amplifier

1.3 SIM Interface 1–5
1.3.2 Direct interfacing
The SIM984 is intended for operation in the SIM900 Mainframe, but
users may wish to directly interface the module to their own systems
without the use of additional hardware.
The mating connector needed is a standard DB–15 receptacle, such
as Amp part # 747909-2 (or equivalent). Clean, well-regulated sup-
ply voltages of ±15,+5 and +24 VDC must be provided, following
the pin-out specified in Table 1.1. Ground must be provided on
pins 1 and 8, with chassis ground on pin 9. The −STATUS signal
may be monitored on pin 2 for a low-going TTL-compatible output
indicating a status message.
1.3.2.1 Direct interface cabling
If the user intends to directly wire the SIM984 independent of the
SIM900 Mainframe, communication is usually possible by directly
connecting the appropriate interface lines from the SIM984 DB–15
plug to the RS-232 serial port of a personal computer.1Connect RXD
from the SIM984 directly to RD on the PC, TXD directly to TD. In
other words, a null-modem style cable is not needed.
To interface directly to the DB–9 male (DTE) RS-232 port typically
found on personal computers, a cable must be made with a female
DB–15 socket to mate with the SIM984, 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 know as
a “hydra” cable. The pin-connections are given in Table 1.2.
1.3.2.2 Serial settings
The initial serial port settings at power-on are: 9600 Baud, 8–bits,
no parity, 1 stop bit, and no flow control. The serial baud rate and
word size are fixed, but the parity may be changed with the PARI
command.
1Although the serial interface lines on the DB-15 do not satisfy the minimum
voltage levels of the RS-232 standard, they are typically compatible with desktop
personal computers
SIM984 Isolation Amplifier

1–6 Getting Started
DB–15/F to SIM984 Name
DB–9/F
10 ←→ 3 TxD
11 ←→ 2 RxD
5 Computer Ground
to P/S
7←→ −15 VDC
13 ←→ +5 VDC
14 ←→ +15 VDC
15 ←→ +24 VDC
8,9 ←→ Ground (P/S return current)
1←→ Signal Ground (separate wire to Ground)
Table 1.2: SIM984 Direct Interface Cable Pin Assignments
SIM984 Isolation Amplifier

2 Remote Operation
This chapter describes operating the SIM984 over the serial interface.
In This Chapter
2.1 Index of Common Commands ............. 2–2
2.2 Alphabetic List of Commands ............. 2–3
2.3 Introduction ........................ 2–4
2.3.1 Power-on configuration ............. 2–4
2.3.2 Buffers ....................... 2–4
2.3.3 Device Clear .................... 2–4
2.4 Commands ........................ 2–4
2.4.1 Command Syntax ................. 2–5
2.4.2 Notation ...................... 2–6
2.4.3 Examples ..................... 2–6
2.4.4 Amplifier Commands .............. 2–7
2.4.5 Status Commands ................ 2–7
2.4.6 Interface Commands ............... 2–9
2.5 Status Model ....................... 2–13
2.5.1 Status Byte (SB) .................. 2–13
2.5.2 Service Request Enable (SRE) .......... 2–14
2.5.3 Standard Event Status (ESR) .......... 2–15
2.5.4 Standard Event Status Enable (ESE) ...... 2–15
2.5.5 Communication Error Status (CESR) ...... 2–15
2.5.6 Communication Error Status Enable (CESE) . 2 – 16
2–1

2–2 Remote Operation
2.1 Index of Common Commands
symbol definition
i,jIntegers
zLiteral token
(?)Required for queries; illegal for set commands
var parameter always required
{var }required parameter for set commands; illegal for queries
[var ]optional parameter for both set and query forms
Amplifier
GAIN(?) {i}2 – 7 Gain
BWTH(?) {i}2 – 7 Bandwidth
Status
*STB? [i]2 – 7 Status Byte
*SRE(?) [i,]{j}2 – 7 Service Request Enable
*CLS 2 – 7 Clear Status
*ESR? [i]2 – 8 Standard Event Status
*ESE(?) [i,]{j}2 – 8 Standard Event Status Enable
CESR? [i]2 – 8 Comm Error Status
CESE(?) [i,]{j}2 – 8 Comm Error Status Enable
OVLD? 2 – 8 Overload Condition
PSTA(?) {z}2 – 9 Pulse −STATUS Mode
Interface
*RST 2 – 9 Reset
*IDN? 2 – 9 Identify
*OPC(?) 2 – 9 Operation Complete
CONS(?) {z}2 – 10 Console Mode
LEXE? 2 – 10 Execution Error
LCME? 2 – 11 Command Error
PARI(?) {z}2 – 11 Parity
TOKN(?) {z}2 – 11 Token Mode
TERM(?) {z}2 – 12 Response Termination
SIM984 Isolation Amplifier

2.2 Alphabetic List of Commands 2–3
2.2 Alphabetic List of Commands

*CLS 2 – 7 Clear Status
*ESE(?) [i,]{j}2 – 8 Standard Event Status Enable
*ESR? [i]2 – 8 Standard Event Status
*IDN? 2 – 9 Identify
*OPC(?) 2 – 9 Operation Complete
*RST 2 – 9 Reset
*SRE(?) [i,]{j}2 – 7 Service Request Enable
*STB? [i]2 – 7 Status Byte
B
BWTH(?) {i}2 – 7 Bandwidth
C
CESE(?) [i,]{j}2 – 8 Comm Error Status Enable
CESR? [i]2 – 8 Comm Error Status
CONS(?) {z}2 – 10 Console Mode
G
GAIN(?) {i}2 – 7 Gain
L
LCME? 2 – 11 Command Error
LEXE? 2 – 10 Execution Error
O
OVLD? 2 – 8 Overload Condition
P
PARI(?) {z}2 – 11 Parity
PSTA(?) {z}2 – 9 Pulse −STATUS Mode
T
TERM(?) {z}2 – 12 Response Termination
TOKN(?) {z}2 – 11 Token Mode
SIM984 Isolation Amplifier

2–4 Remote Operation
2.3 Introduction
Remote operation of the SIM984 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 isolation amplifier from a remote computer, either through the
SIM900 Mainframe or directly via RS-232 (see Section 1.3.2.1).
2.3.1 Power-on configuration
The settings for the remote interface are 9600 baud with no parity
and no flow control, and local echo disabled (CONS OFF).
Most of the SIM984 instrument settings are stored in non-volatile
memory, and at power-on the instrument returns to the state it was
last in when power was removed. Exceptions are noted in the com-
mand descriptions.
Reset values of parameters are shown in boldface.
2.3.2 Buffers
Incoming data from the host interface is stored in a 32-byte input
buffer. Characters accumulate in the input buffer until a command
terminator (either CRor LF) is received, at which point the mes-
sage is parsed and executed. Query responses from the SIM984 are
buffered in a 32-byte output queue.
If the input buffer overflows, then all data in both the input buffer
and the output queue are discarded, and an error is recorded in the
CESR and ESR status registers.
2.3.3 Device Clear
The SIM984 host interface can be asynchronously reset to its power-
on configuration by sending an RS-232-style breaksignal. From
the SIM900 Mainframe, this is accomplished with the SIM900 SRST
command; if directly interfacing via RS-232, then use a serial break
signal. After receiving the Device Clear, the interface is reset and
CONS mode is turned OFF. Note that this only resets the communi-
cation interface; the basic function of the SIM984 is left unchanged;
to reset the instrument, see *RST.
2.4 Commands
This section provides syntax and operational descriptions for reo-
mote commands.
SIM984 Isolation Amplifier

2.4 Commands 2–5
2.4.1 Command Syntax
The four letter mnemonic (shown in CAPS) in each command se-
quence specifies the command. The rest of the sequence consists of
parameters.
Commands may take either set or query form, depending on whether
the “?” character follows the mnemonic. Set only commands are
listed without the “?”, query only commands show the “?” after the
mnemonic, and optionally query commands are marked with a “(?)”.
Parameters shown in {}and [ ] are not always required. Parameters in
{}are required to set a value, and are omitted for queries. Parameters
in [ ] are optional in both set and query commands. Parameters listed
without any surrounding characters are always required.
Do not send()or{}or [ ] as part of the command.
Multiple parameters are separated by commas. Multiple commands
may be sent on one command line by separating them with semi-
colons (;) so long as the input buffer does not overflow. Commands
are terminated by either CRor LFcharacters. Null commands
and whitespace are ignored. Execution of command(s) does not
begin until the command terminator is received.
Token parameters (generically shown as zin the command de-
tokens
scriptions) can be specified either as a keyword or integer value.
Command descriptions list the valid keyword options, with each
keyword followed by its corresponding integer value. For example,
to set the response termination sequence to 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.
SIM984 Isolation Amplifier

2–6 Remote Operation
2.4.2 Notation
The following table summarizes the notation used in the command
descriptions:
symbol definition
i,jIntegers
zLiteral token
(?)Required for queries; illegal for set commands
var parameter always required
{var }required parameter for set commands; illegal for queries
[var ]optional parameter for both set and query forms
2.4.3 Examples
Each command is provided with a simple example illustrating its
usage. In these examples, all data sent by the host computer to
the SIM984 are set as straight teletype font, while responses
received the host computer from the SIM984 are set as slanted
teletype font.
The usage examples vary with respect to set/query, optional param-
eters, and token formats. These examples are not exhaustive, but are
intended to provide a convenient starting point for user program-
ming.
SIM984 Isolation Amplifier