Agilent Technologies 8712ET Manual

Programmer’s Guide
Agilent Technologies 8712ET/ES and 8714ET/ES
RF Network Analyzers
Part No. 08714-90015
Printed in USA
Print Date: June 2000
Supersedes: October 1999
© Copyright 1998-2000 Agilent Technologies, Inc.

ii Programmer’sGuide
Notice
The information contained in this document is subject to change without
notice.
Agilent Technologies makes no warranty of any kind with regard to this
material, including but not limited to, the implied warranties of
merchantability and fitness for a particular purpose.
Agilent Technologies shall not be liable for errors contained herein or for
incidental or consequential damages in connection with the furnishing,
performance, or use of this material.
Key Conventions
This manual uses the following conventions:
: This represents a key physically located on the
analyzer (a “hardkey”).
: This indicates a “softkey”-- a key whose label is determined
by the instrument’s firmware, and is displayed on the right side of the
instrument’s screen next to the eight unlabeled keys.
Firmware Revision
This manual documents analyzers with firmware revisions E.06.00 and
above.
FRONT PANEL KEY
Softkey

Programmer’s Guide iii
GPIB Programming
This document is an introduction to programming your analyzer over the
general purpose interface bus (GPIB). Its purpose is to provide concise
information about the operation of the instrument under GPIB control.
It provides some background information on the GPIB and some short
programming examples to demonstrate the remote operation of the
analyzer.
Example programs can be run on the analyzer’s internal controller or on
an external controller. These programs can be found in the following
three locations:
•Example Programs Disk (included with the analyzer)— DOS Format :
part number 08714-10003.
A LIF version of the Example Programs Disk is available, but is not
shipped with your analyzer:
ExamplePrograms Disk – LIF Format part number 08714-10004.
Contact the nearest Agilent Technologies sales office for ordering
information. A list of Agilent Technologies sales and service offices
can be found in the “Specifications” chapter of the User’s Guide.
•Example Programs Guide (included with the analyzer): part number
08714-90016. (This document may not include all of the example
programs found on the disk or on the Web site.)
• Web site http://www.agilent.com. Use the search function to find
Web pages related to 8712 example programs.
You should become familiar with the operation of your network analyzer
before controlling it over GPIB. This document is not intended to teach
programming or to discuss GPIB theory except at an introductory level.
Related information can be found in the following references:
• Information on making measurements with the analyzer is available
in the analyzer’s User’s Guide.
• Information on HP Instrument BASIC is available in the
HP Instrument BASIC User’s Handbook.

iv Programmer’sGuide
• Information on HP BASIC programming is available in the manual
set for the BASIC revision being used. For example: BASIC 7.0
Programming Techniques and BASIC 7.0 Language Reference.
• Example programs are described in Example Programs Guide.
• Information on using the GPIB is available in the Tutorial
Description of the Hewlett-Packard Interface Bus (HP literature
no. 5021-1927).
• Information on using the analyzer to make automated measurements
is available in Automated Measurements User’s Guide Supplement.
• Information on using the analyzer with a Local Area Network (LAN)
is available in The LAN Interface User’s Guide.
Contact the nearest Agilent Technologies sales office for ordering
information. A list of sales and service offices can be found in the
“Specifications” chapter of the User’s Guide.

Programmer’s Guide v
Agilent Technologies 8712ET/ES and
8714ET/ES Network Analyzer
Documentation Map
The CDROM provides the contents of all of the documents
listed below.
The User’s Guide shows how to make measurements,
explains commonly-used features, and tells you how to get
the most performance from the analyzer.
The LAN Interface User’s Guide Supplement shows
how to use a local area network (LAN) for programming and
remote operation of the analyzer.
The Automating Measurements User’s Guide
Supplement provides information on how to configure and
control test systems for automation of test processes.
The Programmer’s Guide provides programming
information including GPIB and SCPI command references,
as well as short programming examples.

vi Programmer’sGuide
The Example Programs Guide provides a tutorial
introduction using BASIC programming examples to
demonstrate the remote operation of the analyzer.
The Service Guide provides the information needed to
adjust, troubleshoot, repair, and verify analyzer
conformance to published specifications.
The HP Instrument BASIC User’s Handbook describes
programming and interfacing techniques using
HP Instrument BASIC, and includes a language reference.
The HP Instrument BASIC User’s Handbook
Supplement shows how to use HP Instrument BASIC to
program the analyzer.
The Option 100 Fault Location and Structural Return
Loss Measurements User’s Guide Supplement provides
theory and measurement examples for making fault location
and SRL measurements. (Shipped only with Option 100
analyzers.)
The CATV Quick Start Guide provides abbreviated
instructions for testing the quality of coaxial cables.
(Shipped only with Option 100 analyzers.)
The Cellular Antenna Quick Start Guide provides
abbreviated instructions for verifying the performance of
cellular antenna systems. (Shipped only with Option 100
analyzers.)

Contents
Programmer’s Guide Contents-vii
1. Introduction to GPIB Programming
Introduction to GPIB Programming. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
Bus Structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
Data Bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
Handshake Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
Control Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Sending Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
GPIB Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
Interface Capabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8
Programming Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9
Controller Capabilities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9
Response to Bus Management Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10
Message Exchange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-13
2. Synchronizing the Analyzer and a Controller
Synchronizing the Analyzer and a Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Overlapped Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
Controlling Execution of Overlapped Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
Using *WAI and *OPC? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
3. Passing Control
Passing Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
4. Data Types and Encoding
Data Types and Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
Data Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
Numeric Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
Character Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
String Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4
Expression Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4
Block Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4
Data Encoding for Large Data Transfers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
ASCII Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7
Binary Encoding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7
Byte Swapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7

Contents-viii Programmer’sGuide
Contents
5. Using Status Registers
Using Status Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-2
General Status Register Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-3
Condition Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-4
Transition Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-4
Event Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-4
Enable Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-5
How to Use Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-6
The Service Request Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-7
Generating a Service Request . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-8
The Analyzer's Status Register Sets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-10
Status Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-12
Device Status Register Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-15
Limit Fail Register Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-16
Questionable Status Register Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-19
Standard Event Status Register Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-20
Measuring Status Register Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-23
Averaging Status Register Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-23
Operational Status Register Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-24
Settings for STATus:PRESet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-25
Analyzer Register Set Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-26
6. Trace Data Transfers
Trace Data Transfers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-2
Querying the Measurement Trace Using BASIC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-3
Smith Chart and Polar Formats. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-4
Querying the Measurement Trace Using SICL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-5
Using Binary Data Encoding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-6
Trace Data Transfer Sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-8
Transferring Data with IBASIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-10
Taking Sweeps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-11
CALC:DATA? versus TRACE:DATA? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-12
Querying Single Data Points Using Markers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-13
Accessing Other Measurement Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-14
Applying Gain Correction Using the Memory Trace . . . . . . . . . . . . . . . . . . . . . . . . . .6-16
Performing Your Own Data Processing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-18

Contents
Programmer’s Guide Contents-ix
Downloading Trace Data Using Binary Encoding. . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-20
Internal Measurement Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-21
Raw Data Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-21
Ratio Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-22
Error Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-22
Error Coefficient Arrays. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-23
Averaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-25
Corrected Data Arrays. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-25
Corrected Memory Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-25
Trace Math Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-26
Electrical Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-26
Transform (Option 100 only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-26
Formatting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-26
Formatted Arrays. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-26
Offset and Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-27
7. Using Graphics
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2
Window Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4
The Graphics Buffer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6
8. Front Panel Keycodes
Front Panel Keycodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2
Controlling the Front Panel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2
Monitoring the Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2
9. Introduction to SCPI
Introduction to SCPI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2
The Command Tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3
Sending Multiple Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-7
Command Abbreviation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-8
Implied Mnemonics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-9
Parameter Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-10
Numeric Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-10
Character Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-11
Boolean Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-12

Contents-x Programmer’sGuide
Contents
String Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-13
Block Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-13
Syntax Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-14
IEEE 488.2 Common Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-16
10. Menu Map with SCPI Commands
How to Enter Numbers and Characters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-4
How to Enter Frequency Values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-5
How to Enter Time Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-6
How to Enter Power and Voltage Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-7
How to Enter Text. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-8
Menu Map for 8712ET/ES and 8714ET/ES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-9
11. SCPI Command Summary
Queries, Forms, and Parameter Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-2
Parameter Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-3
SCPI Device Command Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-4
12. SCPI Conformance Information
SCPI Conformance Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12-2
SCPI Standard Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12-3
Instrument Specific Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12-10
13. SCPI Error Messages
SCPI Error Messages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13-2
Command Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13-3
Execution Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13-8
Device-Specific Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13-15
Query Errors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13-17

1-1
1 Introduction to GPIB
Programming

1-2 Programmer’s Guide
Introduction to GPIB Programming
Introduction to GPIB Programming
Introduction to GPIB Programming
GPIB—the general purpopse interface bus—is a high-performance bus
that connects individual instruments and computers together to make
integrated test systems. The bus and its associated interface operations
are defined by the IEEE 488.1 standard. The IEEE 488.2 standard
defines the interface capabilities of instruments and controllers in a
measurement system, including some frequently used commands.
GPIB cables provide the physical link between devices on the bus. There
are eight data lines on each cable that are used to send data from one
device to another. Devices that send data over these lines are called
Talkers.Listeners are devices that receive data over the same lines.
There are also five control lines on each cable that are used to manage
traffic on the data lines and to control other interface operations.
Controllers are devices that use these control lines to specify the talker
and listener in a data exchange. When a GPIB system contains more
that one device with controller capabilities, only one of the devices is
allowed to control data exchanges at any given time. The device
currently controlling data exchanges is called the Active Controller.
Also, only one of the controller-capable devices can be designated as the
System Controller, the one device that can take control of the bus even
if it is not the active controller. The network analyzer can act as a talker,
listener, active controller or system controller at different times.
GPIB addresses provide a way to identify devices on the bus. Each device
on the bus must have a unique address. The active controller uses GPIB
addresses to specify which device talks and which device listens during a
data exchange. Device addresses are set on each device using either a
front-panel key sequence or a rear-panel switch.
To set the GPIB address on the analyzer, use the softkeys located in the
menu. The factory default address for the
analyzer is 16.
SYSTEM OPTIONS
GPIB

Programmer’s Guide 1-3
Introduction to GPIB Programming
Introduction to GPIB Programming
NOTE Throughout this manual, the following conventions are used:
•Square brackets ([ ])are used to enclose a keyword that is
optional or implied when programming the command; that is, the
instrument will process the command to have the same effect
whether the option node is omitted or not.
•Parameter types (< >)are distinguished by enclosing the type
name in angle brackets.
•A vertical bar (|)can be read as “or” and is used to separate
alternative parameter options.
• A is a labeled button on the instrument front panel.
• A is one of the eight unlabeled buttons along the right side
of the instrument display. The function of each is indicated
next to the on the instrument display.
HARDKEY
Softkey
Softkey
Softkey

1-4 Programmer’s Guide
Introduction to GPIB Programming
Bus Structure
Bus Structure
Data Bus
The data bus consists of eight lines that are used to transfer data from
one device to another. Programming commands and data sent on these
lines are typically encoded in the ASCII format, although binary
encoding is often used to speed up the transfer of large arrays. Both
ASCII and binary data formats are available to the analyzer. In addition,
every byte transferred over GPIB undergoes a handshake to ensure
valid data.
Handshake Lines
A three-line handshake scheme coordinates the transfer of data between
talkers and listeners. This technique forces data transfers to occur at the
speed of the slowest device, and ensures data integrity in multiple
listener transfers. With most computing controllers and instruments, the
handshake is performed automatically, which makes it transparent to
the programmer.

Programmer’s Guide 1-5
Introduction to GPIB Programming
Bus Structure
Control Lines
The data bus also has five control lines that the controller uses both to
send bus commands and to address devices:
IFC Interface Clear. Only the system controller uses this
line. When this line is true (low), all devices (addressed
or not) are deselected, and go to an idle state.
ATN Attention. The active controller uses this line to define
whether the information on the data bus is a
command or is data. When this line is true (low), the
bus is in the command mode and the data lines carry
bus commands. When this line is false (high), the bus is
in the data mode and the data lines carry
device-dependent instructions or data.
SRQ Service Request. This line is set true (low) when a
device requests service: the active controller services
the requesting device. The analyzer can set the SRQ
line true (low) for a variety of reasons.
REN Remote Enable. Only the system controller uses this
line. When this line is set true (low), the bus is in the
remote mode and devices are addressed either to listen
or talk. When the bus is in remote mode and a device is
addressed, the device receives instructions from GPIB
rather than from its front panel (pressing the
softkey returns the device to front
panel operation). When this line is set false (high), the
bus and all devices return to local operation.
EOI End or Identify. This line is used by a talker to indicate
the last data byte in a multiple byte transmission, or by
an active controller to initiate a parallel poll sequence.
The analyzer recognizes the EOI line as a terminator
and it sets the EOI line true (low) with the last byte of
a message output (data, markers, plots, prints, error
messages). The analyzer does not respond to parallel
poll.
Return to Local

1-6 Programmer’s Guide
Introduction to GPIB Programming
Sending Commands
Sending Commands
Commands are sent over the GPIB via a controller's language system,
such as IBASIC, QuickBASIC or C. The keywords used by a controller to
send GPIB commands vary among systems. When determining the
correct keywords to use, keep in mind that there are two different kinds
of GPIB commands:
• Bus management commands, which control the GPIB interface.
• Device commands, which control analyzer functions.
Language systems usually deal differently with these two kinds of GPIB
commands. For example, HP BASIC uses a unique keyword to send each
bus management command, but always uses the keyword OUTPUT to
send device commands.
The following example shows how to send a typical device command:
OUTPUT 716;"CALCULATE:MARKER:MAXIMUM"
This sends the command CALCULATE:MARKER:MAXIMUM to the GPIB
device at address 716. If the device is an analyzer, the command
instructs the analyzer to set a marker to the maximum point on the data
trace.

Programmer’s Guide 1-7
Introduction to GPIB Programming
GPIB Requirements
GPIB Requirements
Number of Interconnected Devices:
15 maximum
Interconnection Path/Maximum Cable Length:
20 meters maximum or 2 meters per device, whichever is less.
Message Transfer Scheme:
Byte serial/bit parallel asynchronous data transfer using a
3-line handshake system.
Data Rate:
Maximum of 1 megabyte per second over limited distances
with tri-state drivers. The actual data rate is the transfer rate
of the slowest device involved.
Address Capability:
Primary addresses: 31 talk, 31 listen. A maximum of 1 talker
and 14 listeners at one time.
Multiple Controller Capability:
In systems with more than one controller (like the analyzer
system), only one can be active at a time. The active controller
can pass control to another controller, but only the system
controller can assume unconditional control. Only one system
controller is allowed. The system controller is hard-wired to
assume bus control after a power failure.

1-8 Programmer’s Guide
Introduction to GPIB Programming
Interface Capabilities
Interface Capabilities
The analyzer has the following interface capabilities, defined by the
IEEE 488.1 standard:
Table 1-1 Analyzer Interface Capabilities (IEEE 488.1)
1. only when an HP Instrument BASIC program is running
2. only when an HP Instrument BASIC program is not running
SH1 full Source handshake capability
AH1 full Acceptor handshake capability
T6 basic Talker, Serial Poll, no Talk Only, unaddress if MLA
TE0 no Extended Talker capability
L4 basic Listener, no Listen Only, unaddress if MTA
LE0 no Extended Listener capability
SR1 full Service Request capability
RL1 full Remote/Local capability
DC1 full Device Clear capability
C1 System Controller capability
C2 send IFC and take charge Controller capability
C3 send REN Controller capability
C41respond to SRQ
C8 1send IFC, receive control, pass control, pass control to self
C12 2send IF messages, receive control, pass control
E2 tri-state drivers
DT1 full device trigger capability
PP0 no parallel poll capability

Programmer’s Guide 1-9
Introduction to GPIB Programming
Programming Fundamentals
Programming Fundamentals
This section includes specific information for programming your network
analyzer. It includes how the analyzer interacts with a controller, how
data is transferred between the analyzer and a controller, and how to use
the analyzer's status register structure to generate service requests.
Controller Capabilities
The analyzer can be configured as a GPIB system controller or as a
talker/listener on the bus. To configure the analyzer, select either the
or the softkey in the
menu.
The analyzer is not usually configured as the system controller unless it
is the only controller on the bus. This setup would be used if the analyzer
only needed to control printers or plotters. It would also be used if HP
Instrument BASIC was being used to control other test equipment.
When the analyzer is used with another controller on the bus, it is
usually configured as a talker/listener. In this configuration, when the
analyzer is given control it can function as the active controller.
System Controller
Talker Listener
SYSTEM OPTIONS
GPIB

1-10 Programmer’s Guide
Introduction to GPIB Programming
Programming Fundamentals
Response to Bus Management Commands
The GPIB contains an attention (ATN) line that determines whether the
interface is in command mode or data mode. When the interface is in
command mode (ATN TRUE), a controller can send bus management
commands over the bus. Bus management commands specify which
devices on the interface can talk (send data) and which can listen
(receive data). They also instruct devices on the bus, either individually
or collectively, to perform a particular interface operation.
This section describes how the analyzer responds to the GPIB
management commands. The commands themselves are defined by the
IEEE 488.1 standard. Refer to the documentation for your controller's
language system to determine how to send these commands.
Device Clear (DCL)
When the analyzer receives this command, it does the following:
• clears its input and output queues
• resets its command parser (so it is ready to receive a new program
message)
• cancels any pending *OPC command or query
The command does not affect the following:
• front panel operation
• any analyzer operations in progress (other than those already
mentioned)
• any instrument settings or registers (although clearing the output
queue may indirectly affect the status byte's Message Available
(MAV) bit)
Go To Local (GTL)
This command returns the analyzer to local (front-panel) control. All
keys on the analyzer's front-panel are enabled.