Ceyear 3986 Series Owner's manual

3986 Series
Noise Figure Analyzer
Programming Manual

This manual is suitable for the following models of noise figure analyzer:
3986A Noise figure analyzer (10 MHz - 4GHz)
3986D Noise figure analyzer (10 MHz - 18GHz)
3986E Noise figure analyzer (10 MHz - 26.5GHz)
3986F Noise figure analyzer (10 MHz - 40GHz)
3986H Noise figure analyzer (10 MHz - 50GHz)
Options:
3986-H01, 16603/16604 series noise source: used as a noise power standard for noise figure
measurements.
3986-H02, 711XX series high-performance co-axial adapter: used to connect the noise source to
the noise figure analyzer.
3986-H03, multi-core cable: used for smart noise source driver interface and noise source
connection of noise figure analyzer.
3986-H04, BNC(m)-BNC(m): used for connection of standard noise source driver interface and
standard noise source for noise figure analyzer
3986-H05, aluminum alloy transportation case: high-strength, lightweight aluminum alloy
transportation case that comes with handle and wheels for ease of transport.
3986-H98, English option: English display, English manual, English interface, and English operating
system.

Manual Authorization
This manual may be subject to
change without notice. CETI
reserves all the rights to the
final explanation for all the
information and terminologies
referred to in this manual.
This manual is the property of
CETI. Without CETI's
permission, any organizations
or individuals shall neither alter
nor duplicate/transmit this
manual for profits; otherwise,
CETI reserves the right to
pursue any liabilities therefrom.
Product Warranty
The warranty period of this
product is 18 months from the
date of delivery. Instrument
manufacturer will repair or
replace the damaged parts
according to the user's
requirements and actual
situation in the warranty period.
The specific maintenance
matters should be subject to
the contract.
Product Quality
Certification
This product is certified to fulfill
the standards indicated in this
manual from the day of delivery.
Calibration measurements
have been carried out based on
national standards. Related
information is available to the
user for reference.
Quality/Environmental
Management
The quality and environmental
management systems have
always been implemented
during development,
manufacturing and test of this
product. China Electronics
Technology Instruments Co.,
Ltd. has been properly qualified
and certified by ISO 9001 and
ISO 14001 management
system standards.
Safety Precautions
CAUTION indicates an
important information rather
than danger. It reminds the
user to be cautious of a certain
operation process, operation
method or the similar. Failure to
follow the rules or operate
correctly may cause the
damage to the instrument or
loss of important data. The
conditions indicated by
CAUTION should be fully
understood and met before the
next operation.
NOTE indicates an information
prompt. It reminds the user to
pay attention to the instrument
or a certain operation process,
operation method or the similar,
so as to guide the instrument
operator to correctly use the
instrument.
CAUTION
NOTE

3986 Series noise figure analyzer
Table of Contents
1
Table of Contents
1 About This Manual ..................................................................................................1
1.1 About This Manual......................................................................................................................1
1.2 Related Documents....................................................................................................................2
2Remote Control.....................................................................................................3
2.1 Remote control basis.................................................................................................3
2.1.1 Remote interface........................................................................................................................... 3
2.1.2 Message.................................................................................................................................... 5
2.1.3 SCPI........................................................................................................................................... 6
2.1.4 Command sequence and synchronization......................................................................... 13
2.1.5 Status reporting system........................................................................................................ 15
2.1.6 Error Queue................................................................................................................................. 20
2.1.7 Programming considerations ............................................................................................... 21
2.2 Remote interface and its configuration...................................................................22
2.2.1 LAN............................................................................................................................................... 22
2.2.2 GPIB.............................................................................................................................................. 23
2.3 I/O library.....................................................................................................................23
2.3.1 Overview of I/O library........................................................................................................... 24
2.3.2 Installation and configuration of I/O library......................................................................... 24
3 SCPI ........................................................................................................................26
3.1 Command description..............................................................................................................26
3.2 Common Commands...............................................................................................................26
*CLS........................................................................................................................................................ 27
*ESE ....................................................................................................................................................... 27
*ESR?..................................................................................................................................................... 27
*IDN?...................................................................................................................................................... 27
*OPC....................................................................................................................................................... 27
*RST ....................................................................................................................................................... 27
*SRE....................................................................................................................................................... 27
*STB? ..................................................................................................................................................... 28
*TRG....................................................................................................................................................... 28
*WAI........................................................................................................................................................ 28
3.3 Instrument-specific Commands..............................................................................................29

3986 Series noise figure analyzer
Table of Contents
2
3.3.1 Frequency............................................................................................................................... 29
3.3.2 Average/BW................................................................................................................................. 33
3.3.3 ENR............................................................................................................................................... 35
3.3.4 Loss Compensation.................................................................................................................... 42
3.3.5 Mode Setup.................................................................................................................................. 46
3.3.6 Calibration............................................................................................................................... 60
3.3.7 Measurement Results................................................................................................................ 61
3.3.8 Display..................................................................................................................................... 68
3.3.9 Limit Line...................................................................................................................................... 75
3.3.10 Marker........................................................................................................................................ 79
3.3.11 Correction .................................................................................................................................. 82
3.3.12 Sweep......................................................................................................................................... 84
3.3.13 Traces......................................................................................................................................... 88
3.3.14 File .............................................................................................................................................. 93
3.3.15 Noise Source Setup................................................................................................................. 97
3.3.16 System........................................................................................................................................ 98
3.3.17 Preset......................................................................................................................................... 98
4 Programming example .......................................................................................100
4.1 Basic operation example.......................................................................................................100
4.1.1 VISA library................................................................................................................................ 100
4.1.2 Example running environment................................................................................................ 101
4.1.3 Initialization and default status setting................................................................................... 102
4.1.4 Sending of setting command.............................................................................................. 103
4.1.5 Reading of instrument status ............................................................................................. 103
4.1.6 Reading of Markers (Test Receiver Class)........................................................................... 103
4.1.7 Synchronization of command............................................................................................. 104
4.2 Advanced operation example...............................................................................................105
4.2.1 Setting Point Frequency for LAN Interface and Query (SOCKET) ................................... 105
4.2.2 Setting VISA Mode for LAN Interface.................................................................................... 107
4.2.3 Setting Point Frequency for GPIB Interface and Query...................................................... 109
5 Error Description..................................................................................................112
5.1 Error information.....................................................................................................................112
5.1.1 Local error information............................................................................................................. 112

3986 Series noise figure analyzer
Table of Contents
3
5.1.2. Remote control error information........................................................................................... 112
5.2 Repair Method.........................................................................................................................114
5.2.1 Contact us............................................................................................................................. 114
5.2.2 Packaging and delivery....................................................................................................... 114
Appendixes..............................................................................................................116
Appendix A Quick Search Table of SCPIs................................................................................116
Appendix B Quick Search Table of Error Messages...............................................................126

3986 Series noise figure analyzer
Table of Contents
4

1 About This Manual
1.1 About This Manual
1
1 About This Manual
This chapter introduces the functions, compositions, and main content in the Programming Manual of
3986 series noise figure analyzer as well as other related documents provided to the user.
About this manual……………………………………………………………………………………………1
Related Documents…………………………………………………………………………………………2
1.1 About This Manual
This manual introduces the remote control and the SCPI operation method of the 3986 series noise
figure analyzer, as well as the programming examples and the basic concept of the I/O function library to
facilitate the user to quickly master the programming method. To facilitate your familiarity with the
instrument, please read this manual carefully before operating the instrument, and then follow the
instructions of manual.
SCPI (Standard Commands for Programmable Instruments) defines standards and methods for remote
control of the instruments, and it is also the programming language for programmable instruments for
electronic test and measurement. The SCPI is based on the specifications and types in IEEE-488.2. For
details, please visit http://www.scpiconsortium.org. This manual describes in detail the SCPIs of the
3986 series noise figure analyzer.
The chapters of the Programming Manual include:
Remote Control
This chapter introduces the remote control methods of the instrument so that the user can rapidly master
the method to control the instrument in a remote way. It is further divided into the following three sections:
remote control basis, which introduces the concepts related to remote control, software configuration,
remote control interface, SCPI, etc.; instrument interface configuration method, which introduces the
connection method and software configuration method of the remote control interface of the 3986 series
noise figure analyzer; the I/O function library, which introduces the basic concept of the instrument driver
and the basic installation and configuration of the IVI-COM/IVI-C driver.
SCPI
The common command, instrument command and compatibility command are introduced by category,
and functions, parameters, and examples of the SCPI are described one by one.
Programming Examples
The basic programming examples and advanced programming examples are given and described in the
form of explanatory note and example code, so as to facilitate the user to quickly master the
programming method of the signal/spectrum analyzer.
Error Description
This chapter includes error information description and repair methods.
Appendixes
It provides the necessary reference information about program control of the 3986 noise figure analyzer,
including quick search tables of SCPIs and error information.

1 About This Manual
1.2 Related Documents
2
1.2 Related Documents
The documents related to the 3986 series noise figure analyzer include:
Quick Start Guide
User Manual
Programming Manual
Online support
Quick Start Guide
This manual introduces the set-up of the instrument as well as the basic operating methods of
measurement with the aim of enabling users to quickly understand the features and operational
procedures of the instrument. Main chapters included in this manual are as follows::
Preparation before Use
Typical Applications
Getting Help
User Manual
This manual gives a detailed introduction of features and operation methods of the instrument, including
information about configuration, measurement, remote control, maintenance, etc. so as to provide users
with an all-round understanding of the features of the instrument and aid users in learning the most
common measurement procedures. Main chapters included in this manual are as follows::
Overview
Start Guide
Operation Guide
Button categories and menu items
Remote Control
Fault Diagnosis and Repair
Specifications and Test Methods
Appendixes
Programming Manual
This manual describes in detail the basics of remote programming, SCPI basics, SCPI, programming
examples, I/O driver library, etc. for the purpose of guiding the user to master the SCPIs and methods of
the instrument quickly and comprehensively. Main chapters included in this manual are as follows::
Remote Control
SCPI
Programming Examples
Error Description
Appendixes
Online support
Online help is integrated in the instrument product to provide quick text navigation help for user local and
remote control operation. The hard keys on the instrument front panel or the user interface toolbars may
be activated with their corresponding shortcut keys. The contents are the same as those in the user
manual.

2 Remote Control
2.1 Remote control basis
3
2 Remote Control
This chapter introduces the remote control basis as well as the remote control interface and its
configuration method of the 3986 series noise figure analyzer, and also briefly describes the concept and
classification of the I/O driver library, so that the user can have a preliminary knowledge about the
remote control of this instrument. The specific content includes:
Remote control basis…………………………………………………………………………………………3
Remote interface and its configuration……………………………………………………………………22
I/O library……………………………………………………………………………………………………23
2.1 Remote control basis
Remote interface……………………………………………………………………………………………3
Message………………………………………………………………………………………………………5
SCPI……………………………………………………………………………………………………………6
Command sequence and synchronization………………………………………………………………13
Status reporting system……………………………………………………………………………………15
Error queue............................................................................……………………………………........20
Programming Considerations……………………………………………………………………………21
2.1.1 Remote interface
LAN interface…………………………………………………………………………………………………3
GPIB interface………………………………………………………………………………………………5
The 3986 noise figure analyzer supports two remote interfaces: LAN and GPIB. The description of the
remote interface and associated VISA addressing string is as shown in the following table:
Table 2.1 Remote Interface Type and VISAAddressing String
Remote
Interface
VISAAddressing String
Description
LAN
(Local Area
Network)
Raw socket protocol:
TCPIP::host_address::port::SOCKET
Controller realizes remote control by
connecting the instrument via the
network port on the rear panel of the
instrument.
See 2.1.2.1 LAN Interface for the
specific protocol
GPIB
(IEC/IEEE Bus
Interface)
GPIB::primary address[::INSTR]
Controller realizes remote control by
connecting the instrument via the port
on the rear panel of the instrument.
It is in compliance with IEC
625.1/IEEE 418 bus interface
standard.
See 2.1.2.2 GPIB Interface for details
2.1.1.1 LAN interface
The noise figure analyzer is available for remote control through the 10Base-T and 100Base-T LAN
computers. The instruments can be combined into a system within the LAN, and uniformly controlled by

2 Remote Control
2.1 Remote control basis
4
the LAN computers. In order to realize the remote control within the LAN, the noise figure analyzer shall
be preinstalled with the port connector, network card and relevant network protocol, and configured with
relevant network service.And, the controller computer within the LAN shall also be preinstalled with the
instrument control software and VISA library. The three working modes of the network card include:
10Mbit/s Ethernet IEEE802.3；
100Mbit/s Ethernet (IEEE802.3);
1Gbit/s Ethernet IEEE802.3ab。
The controller computer and the noise figure analyzer shall be connected to a common TCP/IP protocol
network through network ports. The cables for connecting the computer and the noise figure analyzer
are commercial RJ45 cables (shielded or unshielded CAT 5 twisted pairs). During data transmission,
data packet transmission will be adopted, and LAN transmission is faster. In general, the cables between
the computer and the noise figure analyzer should not exceed 100 m (100 Base-T and 10 Base-T). You
may visit http://www.ieee.org for more information on LAN communications.
Interface:
1) IP address
When the noise figure analyzer is remotely controlled via LAN, the physical network connection shall be
guaranteed to be smooth. Set the address to the subnet where the main control computer resides by
using the “Local IP” command of the noise figure analyzer. For example, if the IP address of the main
control computer is 192.168.12.0, the IP address of the noise figure analyzer should be set to
192.168.12.XXX, where XXX is a value between 1 and 255.
Only the IP address is required to establish a network connection. The VISAaddressing string is as
follows:
TCPIP::host address::port::SOCKET
Where,
TCPIP - network protocol used;
host address - IP address or host name of the instrument, for identification and control of the
controlled instrument;
port identifies the socket port number, 3986 noise figure analyzer;
SOCKET is resource class of original network socket.
Example:
The instrument‟s IP address is 192.1.2.3. When establishing an original socket connection, you may
use:
TCPIP::192.1.2.3::5000::SOCKET
Method for identification of multiple instruments in the remote control system
If multiple instruments are connected to the network, they can be identified by their individual IP address
and associated resource string. The main control computer uses the respective VISA resource string for
instrument identification.
2) Socket communication
The TCP/IP protocol connects the signal sources in the network through the LAN socket. As a basic
computer network programming method, the socket enables applications with different hardware and
NOTE

2 Remote Control
2.1 Remote control basis
5
operating systems to communicate in the network, This method enables two-way communication
between the noise figure analyzer and the computer via port.
The socket is a software class written specifically to define the necessary information for network
communication such as IP address and device port number, and integrates some basic operations in
network programming. Sockets can be used in the operating system installed with a packaged library.
UNIX Berkeley socket and Winsock are commonly used.
The socket in the noise figure analyzer is Berkeley socket and Winsock compatible through the
application program interface (API). In addition, other standard sockets are also compatible through the
API. When the noise figure analyzer is controlled using SCPI command, the socket program created in
the program issues command. Before using the LAN socket, you must set the socket port number of the
noise figure analyzer. The socket port number of the noise figure analyzer is 5000.
2.1.1.2 GPIB interface
The GPIB interface is a widely-used instrument remote interface currently, which can be connected with
different kinds of instruments through the GPIB cable and can establish the test system with the main
control computer. To realize remote control, the main control computer shall be preinstalled with the
GPIB bus card, driver and VISA library. During communication, the main control computer will address
the controlled instrument through the GPIB bus address firstly. The user can set the GPIB address and
ID for querying strings, and the GPIB communication language can be set to the SCPI form by default.
The operation of the GPIB and its relevant interface is defined and described in details in the ANSI/IEEE
standard 488.1-1987 and the ANSI/IEEE standard 488.2-1992. For details of the standard, please refer
to the IEEE website: http://www.ieee.org.
The GPIB processes information in bytes and the data transfer rate can reach 8 MBps. Therefore, the
GPIB data transmission is fast. Since the data transmission speed is limited by the distance between the
device/system and the computer, you need to pay attention to the following matters when you connect
the GPIB:
Up to 15 instruments may be set up through the GPIB interface;
The total length of the transmission cable does not exceed 15 m or does not exceed twice the
number of the instruments in the system. In general, the maximum length of the transmission cables
between devices cannot exceed 2 m.
If you connect multiple instruments in parallel, you need to use “OR” connectors.
The terminal of the IECbus cable shall be connected to the instrument or the controller computer.
2.1.2 Message
Messages transmitted by data cable fall into the following two categories:
1) Interface message
During communication between the instrument and the main control computer, it is necessary to pull
down the attention line and then the interface message can be transmitted to the instrument through the
data line. Only the instrument with the GPIB bus functions can send the interface message.
2) Instrument message
For the structure and syntax of instrument messages, see “5.1.4 SCPIs” for details. The instrument
message can be divided into command and instrument response by transmission direction. Unless
otherwise stated, all remote interfaces should adopt the same method for use of the instrument
message.
a) Commands:
A command (programming message) is a message transmitted from the main control computer to the
instrument for remote control of instrument functions and query of status information. It falls into the
following two categories:
Based on the impact on the instrument:

2 Remote Control
2.1 Remote control basis
6
- Setting command: Change the instrument setting status, e.g. reset the instrument or set the frequency.
- Query command: Query and return the data, e.g. identify the instrument or query the parameter values.
The query command is always ended with a question mark.
Based on the definition in the standard:
- Common commands: Functions and syntax defined by IEEE488.2 for all types of instruments (if
implemented)
Used to implement: manage standard status registers, resets and self-tests.
- Instrument control command: Instrument characteristic command for realizing instrument function. For
example: set the frequency.
The syntax also follows SCPI specification.
b) Instrument response:
The instrument response (response message and service request) is the query result information sent
by the instrument to the computer. This information includes measurement result and instrument status.
2.1.3 SCPI
Introduction to SCPI…………………………………………………………………………………………6
Description of SCPIs………………………………………………………………………………………7
2.1.3.1 Brief introduction to SCPI
SCPI (Standard Commands for Programmable Instruments) is a command set that is established based
on IEEE Standard 488.2 and applicable to all instrument. mainly to achieve the universality of SCPI,
i.e.the same SCPI is generated and issued for the same function.
The SCPI consists of a command header and one or more parameters which are separated by a space.
The command header contains one or more key fields. The command with question mark as postfix is a
query command. Commands are divided into common commands and instrument-specific commands
that are different in syntactic structure. SCPI has the following features:
1) The SCPI is established for the test functions rather than instrument operation description.
2) The SCPI reduces the repetition of the realization process of similar test functions, thus ensuring the
programming compatibility;
3) Remote control message is defined in a layer that is independent of the communication physical
layer hardware.
4) The SCPI is irrelated with the programming methods and languages, and the SCPI test program is
easy to be transplanted;
5) The SCPI is scalable so that it is applicable to measurement control on different scales.
6) Scalability makes SCPI a “Live” standard.
If you are interested in learning more about SCPI, please refer to:
IEEE Standard 488.1-1987, IEEE Standard Digital Interface for
Programmable Instrumentation. New York, NY, 1998.
IEEE Standard 488.2-1987, IEEE Standard Codes, Formats, Protocols and Comment
Commands for Use withANSI/IEEE Std488.1-1987. New York, NY, 1998
Standard Commands for Programmable Instruments(SCPI) VERSION 1999.0.
For the collection of remote control commands, classification and description of 3986 noise factor
analyzer, please refer to:

2 Remote Control
2.1 Remote control basis
7
1) “Programmable Commands” in this manual;
2) “Appendix A Quick Search Table of SCPIs” in this manual;
3) Related manuals for each measurement function.
2.1.3.2 SCPI description
General terms……………………………………………………………………………… ………………7
Command type……………………………………………………………………………………… ………7
Instrument-specific command syntax………………………………………………………… …………8
Command tree………………………………………………………………………………… …………9
Command parameter and response………………………………………………………………………10
Systems of values in command.......................................................…………………............ ...........13
Command line structure.............................................................……………………..........................13
1) General terms
For the purpose of this section, the following terms should apply. It is necessary to know about the exact
definitions of these terms for a better understanding of the content in various chapters.
Controller
The controller is any computer used to communicate with the SCPI equipment. The controller may be a
personal computer, a small computer or a card inserted onto a cage. Some artificial intelligence
equipment can also be used as a controller.
Equipment
The equipment is any device that supports SCPI. Most equipment is electronic measuring or excitation
equipment and use the GPIB interface for communication.
Remote control message
The remote control message is a combination of one or more correctly formatted SCPIs. It guides the
equipment to measure and output the signal.
Response message
The response message is a data set that specifies the SCPI format. It is always sent from the equipment
to the controller or listener to remind the controller of the internal condition or measured value of the
equipment.
Command
A command is an instruction in compliance with the SCPI standard. The combination of controller
commands forms a message. In general, a command includes the keyword, parameter and punctuation.
Event command
An event-type SCPI can't be queried. An event command generally has no corresponding key settings
on front panel. Its function is to trigger an event at a particular moment.
Query
Query is a special command. When the controller is queried, it is necessary to return to the response
message in conformity with syntax requirement of the controller. The query statement is always ended
with a question mark.
2) Command type
There are two types of SCPI commands: common commands and instrument-specific commands.
Figure 5.2 shows the difference between two commands. Common commands are defined in IEEE

2 Remote Control
2.1 Remote control basis
8
488.2 to manage macros, status registers, synchronization, and data storage. Common commands are
easy to recognize as they all begin with an asterisk. For example *IDN? , *OPC and *RST are common
commands. Common commands don‟t belong to any instrument-specific command. The instrument
uses the same method to interpret them without consideration to the current path setting.
It is very easy to identify instrument-specific commands because they contain a colon (:). The colon is
used between the beginning of a command expression and a keyword, for example: FREQuency[:CW?].
Instrument-specific commands are divided into command subsets of corresponding subsystem
according to the functional block inside the instrument. For example, the power subsystem (:POWer)
contains the power-related command while the status subsystem (:STATus) contains the command for
the status control register.
Figure 2.1 SCPI Type
3) Instrument-specific command syntax
A typical command consists of keywords with colon as prefix.. These keywords are followed by
parameters..
An example of a syntax declaration: [:SOURce]:POWer[:LEVel] -10dBm
In the above example, the [:LEVel] portion of the command immediately follows :POWer with no
separating space. The following part [:LEVel]: -10dBm is the parameter part. There is a space between
the command and the parameter. The description of other parts of the syntax expression is as shown in
Table 2.2 and Table 2.3.
Table 2.2 Special Characters in Command Syntax
Symbol
Meaning
Example
|
A vertical stroke between keyword and parameter
indicates alternative choices.
[:SOURce]:AM:
SOURce EXTernal|INTernal
EXTernal and INTernal are
alternative choices
[]
Keywords or parameters in square brackets are
optional when composing the command
. These implied keywords or parameters
also will be executed even if they are ignored.
[:SOURce]:AM[:DEPTh]:EXPon
ential?
SOURce and DEPTh are
dispensable.
< >
The part inside the angle brackets can't be used literally
literally in the command. They represent the needed
item.
[:SOURce]:FREQ:STOP
<val><unit>
In this command, <val> and <unit>
must be replaced by an actual
frequency and unit.
For example:
:FREQ:STOP 3.5GHz
{ }
The part inside the braces indicates that the
parameters in them are optional.
[:SOURce]:LIST:POWer
<val>{,<val>}
For example: LIST:POWer 5
SCPI
Common command
Subsystem commands

2 Remote Control
2.1 Remote control basis
9
Table 2.3 Command Syntax
Character, Keyword and Syntax
Example
Upper-case characters represent the minimum character
set required by
command execution.
[:SOURce]:FREQuency[:CW]?,
FREQ is the short-format part of the
command.
The lower-case characters portion of command is
optional;Such flexible
format is called “flexible listening”. See the “
Command Parameters and Responses” section for more
information.
:FREQuency
:FREQ,:FREQuency or
:FREQUENCY,
any of which is correct.
When a colon is placed between two command
mnemonics,it moves
the current path down one level in the command tree. See
the command path section of “
Command Tree” for more information.
:TRIGger:OUTPut:POLarity?
TRIGger is the topmost keyword of the
command.
If a command requires more than one parameter, you must
separate adjacent parameters
using a comma. Parameters do not affect path layers
as they are not the portion of the command path.
[:SOURce]:LIST:DWELl <val>{,<val>}
A semicolon separates 2 adjacent commands without
affecting the current
path.
:FREQ 2.5GHZ; :POW 10DBM
White space characters, such as <space> or <tab>, are
generally ignored
so long as they don‟t appear between or among keywords
. However, you mustuse white space to separate
parameters from commands, which does not affect the
current path.
:FREQ uency or :POWer :LEVel6.2 is not
allowed.
You must leave a white space
between :LEVel and 6.2.
That is: POWer:LEVel 6.2
4) Command tree
Most remote control programming tasks involve instrument-specific commands. When such a command
is parsed, the SCPI will use a structure similar to the file structure, and it is called as a command tree, as
shown in Figure 2.2:
The top command is root command, or simply “root”. In the case of command parsing, the command at
the next layer is reached by following a specific route based on the tree structure. For
example::POWer:ALC:SOURce?, where, POWer stands for AA,: ALC stands for BB, :SOURce stands
for GG, and the whole command path is (:AA:BB:GG).
AA
BB
CC
DD
EE
FF
GG
HH
JJ
Root
First
level
Second
level
Figure 2.2 Simplified Command Tree Diagram

2 Remote Control
2.1 Remote control basis
10
A software module in the instrument software——command interpreteri s used for parsing each
received SCPI. The command interpreter breaks up the command into individual command element
using a series of rules for identifying the command tree path. After the current command is parsed, the
current command path remains unchanged. In this way, the subsequent commands can be parsed more
quickly and efficiently because the same command keyword may appear in different paths. After the
power-on*RST (reset) operation of the instrument, the current command path is reset as the root.
5) Command parameter and response
The SCPI defines different data formats in the use of the remote control and response messages to
conform to the principles of “flexible listening” and “accurate speaking”. For more information, please
refer to IEEE 488.2. “Flexible listening” means that the formats of commands and parameters are
flexible.
For example,the noise figure analyzer sets the frequency offset state command:FREQuency:
:OFFSet:STATe ON|OFF|1|0,
The following command formats are used to set the frequency offset function on:
:FREQuency:OFFSet:STATe ON，:FREQuency:OFFSet:STATe 1，
:FREQ:OFFS:STAT ON，:FREQ:OFFS:STAT 1.
Each parameter type corresponding to one or more response data types. During query, a numeric data
will return a data type, and the response data is accurate. Strictly speaking, it is called as “accurate
speaking”.
For example, if you query the power state (:POWer:ALC:STATe?), when it is turned on, the response is
always 1, regardless of whether you previously sent :POWer:ALC:STATe 1 or :POWer:ALC:STATe ON.
Table 2.4 Types of SCPI Command Parameter and Response
Parameter Type
Response Data Type
Numeric
Real or Integer
Extended Numeric
Integer
Discrete
Discrete
Boolean
Numeric Boolean
String
String
Block
Definite Length Block
Indefinite Length Block
Non-decimal numeric
Hexadecimal
Octal
Binary
Numeric parameter
Numeric parameters can be used in both instrument-specific commands and common commands. It
receives all common decimal systems including signs, decimal point and scientific notation. If a certain
piece of equipment only receives a specified type of numeric parameter such as an integer, it will
automatically round off the received numeric parameter.
Examples of numeric parameter:
0 No decimal point
100 Optional decimal point
1.23 With a sign bit
4.56e<space>3space allowed after exponent marker e

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-7.89E-01 exponent marker e may be upper or lower case
+256 leading + allowed
5 The decimal point can be prefixed
Extended numeric parameter
Most measurements related to Instrument-specific commands use extended numeric parameters to
specify the physical quantities. Extended numeric parameters receive all numeric parameters and
additional special values. All extended numeric parameters receive MAXimum and MINimum as
parameter values。Other special values, such as UP and DOWN are received by the instrument parsing
capability. SCPI command table will list all valid parameters.
Note: extended numeric parameters are not applicable to common commands or STATus subsystem
commands.
Examples of extended numeric parameters:
101 Numeric parameter
1.2 GHz The GHz can be used as an exponent (E009)
200 MHz The MHz can be used as an exponent (E006)
-100 mV -100 millivolts
10DEG 10 Degree
MAXimum Maximum valid setting
MINimum Minimum valid setting
UP Increase a step
DOWN Decrease a step
Discrete parameter
When there are a finite number of parameter values to be set, discrete parameters are used for
identification. A discrete parameter uses mnemonics to represent each valid setting. Like the SCPI
mnemonics, the discrete parameter mnemonics can be set in long and short formats, with both
capitalized and lowercase characters.
The following example illustrates the combined use of discrete parameter and command.
:TRIGger[:SEQuence]:SOURce BUS|IMMediate|EXTernal
BUS GPIB,LAN,RS-232 trigger
IMMediateImmediate trigger
EXTernal External trigger
Boolean parameter
Boolean parameters represent a single binary condition that is either true or false. There are only four
possible representations for a Boolean parameter.
Samples of Boolean parameters:
ON True
OFF False
1 True
0 False
String parameter

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Astring parameter allows the ASCII string to be sent as a parameter. Single and double quotes are used
as separators.
Examples of string parameter:
„This is Valid‟ “This is also Valid” „SO IS THIS‟
Real response data
A large portion of measurement data are real. They are formatted as basic decimal notation or scientific
notation. Most high-level remote control languages all support these two formats.
Examples of real response data:
1.23E+0
-1.0E+2
+1.0E+2
0.5E+0
0.23
-100.0
+100.0
0.5
Integer response data
The integer response data are a decimal expression of an integer with the sign bit. When the status
register is queried, the integer response data will be mostly returned.
Examples of integer response data:
0 Optional sign bit
+100 Leading + allowed
-100 Leading - allowed
256 No decimal point
Discrete response data
The discrete response data and discrete parameters are basically the same. The main difference is that
the discrete response data can only be returned in the short format with capitalized characters.
Examples of discrete response data:
INTernal Internal amplitude stabilization
EXTernal External amplitude stabilization
MMHead Amplitude stabilization through MMW source module
Numeric Boolean response data
The Boolean response data returns a binary value of 1 or 0.
String response data
The string response data and string parameters are the same. The main difference is that the string
response data use double quotes rather than single quotes as the separator. The string response data
can also be inserted with double quotes inside which there can be no characters.
Examples of string response data:
“This is a string”
“one double quote inside brackets: (“”)”