Agilent 8711C Programming Manual

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Programmer’s Guide

HP 8711C/12C/13C/14C RF Network Analyzers

HP part number: 08712-90057 Printed in USA

August 1998 Supersedes April 1998

Notice

Firmware Revision

The information contained in this document is subject to change without notice.

Hewlett-Packard 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. Hewlett-Packard 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.

This manual documents analyzers with firmware revisions C. 04.52 or later. Some features will not be available or will require different keystrokes in analyzers with earlier firmware revisions. For full compatibility, you can upgrade your firmware to the latest version. Contact your nearest Hewlett-Packard sales or service office for information.

HP-IB Programming

This document is an introduction to programming your analyzer over the Hewlett-Packard Interface Bus (HP-IB). Its purpose is to provide concise information about the operation of the instrument under It provides some background information on the HP-IB and a tutorial introduction using progr

amming

examples to demonstrate the remote operation of the analyzer. The examples are provided on two disks that are included with the analyzer. Both disks contain the same examples written

mainly in HP BASIC; only the disk format is different. These programs can run on the analyzer’s internal controller (Option

lC2)

controller.

Example Programs Disk -

ExammpLe

Programs Disk -

DOSFbvmat

LIFRrrmat

: part number 08712-10019

: part number 08712-10021

You should become familiar with the operation of your network analyzer before controlling it over HP-IB. This document is not intended to teach programming or to discuss HP-IB theory except at an introductory level. Related information can be found in the following references. Contact the nearest HP sales office for ordering information. A list of HP sales and service offices can be found in the “Specifications and Characteristics” chapter of the

User’s Guide.

HP-II3

control.

or on an external

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

BASIC User’s Handbook.

Information on HP BASIC progr

amming

the BASIC revision being used. For example:

Rchniques

Information on using the HP-IB is available in the

the Hewlett-Packard Interface Bus

and

BASIC 7.0 Language

is available in the manual set for

BASIC 7.0 Programming

Reference.

(HP

literature no.

HP Instrument

Tutorial Description

5021-1927).

. . .

111

Contents

Introduction to BP-IB Programming

Bus

Structure

Data

Bus

Handshake Sending Commands HP-IB Requirements Interface Capabilities Programming Fundamentals

Controller Capabilities

Response to

Message

Synchronizing the Analyzer and a Controller

Overlapped Commands The NPO Flag

Usage of

....................

.....................

Lines

Bus

Exchange

*WA1 and *OPC?

.................

................

Management Commands

.................

...................

.............

...............

.............

......

l-4 l-4 l-4 l-6 l-7 1-8 l-9

l-9 l-10 1-13

2-3 2-5 2-7

3. Passing Control

Data Types and Encoding

Data Types

Numeric Data Character Data

String Data Expression Data Block Data

Data Encoding for Large Data Transfers

ASCII Encoding Binary Encoding Byte Swapping

.....................

...................

..................

....................

..................

....................

..................

.................

..................

........

4-3 4-3 4-4 4-4 4-4 4-5 4-7 4-8 4-8 4-9

Contents-l

Query Errors

5. Using Status Registers

General Status Register

Condition Register Transition Registers Event Register Enable Register

How

Use

Registers

The

Service

Generating

The Analyzer’s Status Register

Status Byte

Device Limit Questionable Status Register Standard Event Status Register Measuring Status Register Averaging Status Register Operational Status Register STATus:PRESet Settings Analyzer Register

Request Process

a Service

....................

Status Register

Fail

Model

................

..................

Request

Set

...............

Set

Summary

............

.............

............

Sets

.............

Set

............

Set

..............

Set

...........

..........

.........

5-3 5-4 5-4 5-4 5-5

5-6

5-7

5-8 5-10 5-12 5-15 5-16 5-19 5-20 5-23 5-23 5-24 5-25 5-26

6. Trace Data Transfers

Querying the Measurement Trace

@Smith Chart and Polar Formats

Querying the Measurement Trace Using

Transferring Data with IBASIC : : : : : : : : : : : : Taking

CALC:DATA?

Querying Accessing Applying Gain Correction Using the Memory Trace Performing Downloading Trace Data Internal Measurement Arrays

Contents-2

Binary Data Encoding

Trace Data Transfer Sizes

Sweeps

versus

Single

Other Measurement Arrays

Your Own

Raw

Data Arrays Ratio Calculations Error Correction

Using BASIC

..........

Using SICL

.............

...................

TRACE:DATA?

Data Points Using Markers

Data Processing

Using

.................

............

.........

Binary Encoding

.............

......

.......

.....

....

...

6-3 6-4

6-5 6-7

6-9

6-10 6-11

6-12

6-13 6-14 6-16 6-18 6-20 6-21 6-22 6-23 6-23

Error

Coefficient

Averaging

Corrected Data Arrays Corrected Memory Arrays Trace Math Operation @ Electrical Delay

Arrays

......................

.................

..............

...............

.............

...............

Query Errors

6-23

6-25

6-25 6-25

6-26 6-26

Transform (Option 100 only) Formatting Formatted Arrays Offset and

7. Using Graphics

Window Geometry . . . . . . . . . . . . . . . . .

The Graphics

8. Example Programs

Configuring Measurements

SETUP Example Program LIMITEST Example Program POWERSWP Example Program

Transfer

Calibration

Instrument State and Save/Recall : : : : : : : : : . .

Hardcopy Control

MARKERS Example Program

@SMITHMKR Example Program

ASCDATA

REALDATA

INTDATA Example Program

FAST-C W Example Program

TRANCAL Example Program

REFLCAL Example Program

LOADCALS

CALKIT Example Program

LEARNSTR Example Program

SAVERCL

PRINTPLT Example Program PASSCTRL Example Program

....................

.................

Scale

Data to/from the Analyzer

.....................

Example Program

..................

Buffer . . . . . . . . . . . . . . . .

Example Program

..................

............

..............

.............

............

..........

.........

...........

..........

............

...........

............

...........

............

...........

............

...........

. .

6-26 6-27 6-27 6-27

7-4

7-6

8-7

8-8 8-11 8-16 8-19

S-20

8-24

8-31 8-34 8-38 8-42 8-45 8-46 8-48 8-53

S-60

8-62 8-63 8-66

8-69

8-70 8-73

Contents-3

Query Errors

FAST-PRT Example Program

Service Request

SRQ Example Program SRQ-INT Example Program

File Transfer

GETFILE Example Program

PUTFILE Example Program

Customized Display

GRAPHICS Example Program GRAPH2 Example Program GETPLOT Example Program

Annot ation

USERANOT Example Program FREQBLNK Example Program KEYCODES Example Program

Marker Functions

MKR-MATH Example Program

Marker Limit Testing

LIM-FLAT Example Program LIM-PEAK Example Program LIM-MEAN Example Program

SRL

Measurements (Option 100 only) MEAS-SRL Example Program SRL-SRQ Example Program

Fault Location Measurements (Option 100 only)

FAULT USR-FLOC Example Program

Multiport

PORT-SELection Example Program TSET-CAL Example Program

TTL Output

TTL-IO Example Program

AMDELAY Example Program

Example Program

Test Set

Delay

....................

Over

.....................

HP-IB

.................

..................

Measurements

....................

..............

...............

................

...........

............

...........

............

...........

..........

...........

.........

...........

............

.............

...........

.........

...........

.............

...........

.....

8-77

S-80

8-81

8-85 S-102 S-103

S-105 S-108 S-109 8-116 8-122 8-125 8-126 8-129 8-131 8-134 8-135 8-139 S-140 8-143 8-147 8-151 8-152 8-156

S-160 8-161 8-165 8-168 8-169 8-182 8-186 8-186 8-189 8-189

Contents-4

9. Front Panel Keycodes

10. Introduction to SCPI

The Command Sending Multiple Commands . .

Command Abbreviation . . . .

Implied Mnemonics . . . . . .

Parameter

Numeric Parameters . . . . .

Character Parameters . . . .

Boolean Parameters . . . . .

String Parameters . . . . . .

Block

Syntax Summary . . . . . . .

IEEE 488.2 Common Commands

11.

Menu Map with SCPI Commands

12. SCPI Command Summary

Types . . . . . . .

Tree . . . . .

Parameters . . . . . .

...........

Query Errors

10-3 10-7

10-S

10-9

10-10

10-10 10-11 10-12 10-13 10-14 10-15 10-17

13. SCPI Conformance Information

SCPI Standard Commands . . . Instrument

14. SCPI Error Messages

Command Errors . . . . . . .

Execution Errors . . . . . . .

Device-Specific

Query Errors . . . . . . . . .

Index

Specific

Errors . . . . .

Commands .

...........

13-3 13-9

14-3

14-7 14-12 14-14

Contents-5

Figures

5-1. General Status Register Model . . . . . . . . . . .

5-2. Flow of information within a register set . . . . . .

5-3. Generating a Service Request . . . . . . . . . . . . . . .

5-4. Analyzer Register Sets . . . . . . . . . . . .

5-5. The Status Byte Register Set . . . . _ . . . .

5-6. The Limit Fail Register Set . . . . . . . . . . . . . . .

5-7. The Standard Event Status Register Set . . . . . . . . .

5-8. Analyzer Register Set Summary . . . . . . . . . . . . . .

6-1. Numeric Data Flow Through the Network Analyzer . . .

6-2. Numeric Data Flow Through the Network Analyzer . . . . .

6-3. Numeric Data Flow Through the Network Analyzer . . .

7-l.

Pixel Dimensions with Available Display Partitions . . . . .

10-l.

Measurement and Data 10-2. Partial Diagram of the

10-3. SCPI Command Syntax . . . . . . . . . . . .

Flow

of the Analyzer . . . . .

CALCulate

Subsystem Command Tree .

5-3

5-5

5-8 5-11 5-12 5-17

5-20

5-26

6-2 6-14 6-21

7-4

10-3

10-6

lo-15

Contents-6

lhbles

6-l. Typical Trace Transfer Times (ms)

6-2. Size of Trace Data Transfers (in Bytes) Using the TRACE:DATA

SCPI Command 6-3. Typical Trace Transfer Times (ms) 6-4. Raw Data Arrays 6-5. Error Coefficient Arrays

12-1. Writeable Ports 12-2. Readable Ports

14-1. SCPI Command Errors 14-2. SCPI Execution Errors 14-3. SCPI 14-4. SCPI Query Errors

Device-Specilic

...................

....................

.................

.....................

..................

Errors

....................

................

............

6-7

6-9

6-10 6-22

6-24 12-13 12-14

14-4 14-8

14-13

14-14

Contents-7

Contents

Introduction to HP-IB Programming

HP-IB - the Hewlett-Packard Interface Bus - is a high-performance bus that allows individual instruments and computers to be combined into 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.

HP-IB 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 are devices that receive data over the same lines. There are also five control

lines on each cable that are used to manage

control other interface operations. Controllers are devices that use these control lines to specify the talker and listener in a data exchange. When an

HP-IB 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.

trafhc

on the data lines and to

Talkers.

Listeners

HP-IB addresses provide a way to identify devices on the bus. The active

controller uses HP-IB addresses to specify which device talks and which device listens during a data exchange. This means that each device’s address must be unique. A device’s address is set on the device itself, using either a front-panel key sequence or a rear-panel switch.

To set the HP-IB address on the analyzer use the

[SYSTEM OPTIONS) HP-IB menu. The factory default address for the analyzer

is 16.

l-2

softkeys

located in the

NOTE

Throughout this manual, the following conventions are used:

Introduction to HP-IB Programming

Square brackets

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 A vertical bar (I

Cc II

are used to enclose a keyword that is optional or implied when

(C >I

are distinguished by enclosing the type name in angle brackets.

)

can be read as “or” and is used to separate alternative parameter options.

l-3

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 is 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 HP-IB undergoes a handshake to ensure valid data.

Handshake Lines

Control 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.

The data bus also has five control lines that the controller uses both to send

bus commands and to address devices:

IFC

ATN

l-4

Interface Clear. Only the system controller uses this line.

When this line is true (low) all devices (addressed or not)

unaddress and go to an idle state. 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.

Introduction to HP-IB Programming

Bus

Structure

SRQ

REN

EOI

Service Request. This line is set true (low) when a device requests service: the active controller services the requesting device. The analyzer can be enabled to pull the

SRQ line for a variety of reasons. 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 and a device is addressed, the device receives instructions from HP-IS rather than from its front panel (pressing the

Beturn to Local softkey

returns the device to front panel operation). When this line is set false (high) the bus and all devices return to local operation.

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 pulls the EOI line with the last byte of a message output (data, markers, plots, prints, error messages). The analyzer does not respond to parallel poll.

l-5

Sending Commands

Commands are sent over the HP-IB via a controller’s language system, such as send HP-IB commands vary among systems. When determining the correct keywords to use, keep in mind that there are two different kinds of HP-IB commands:

Language systems usually deal differently with these two kinds of HP-IB 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:

IBASIC, QuickBASIC

or C. The keywords used by a controller to

Bus management commands, which control the HP-IB interface. Device commands, which control analyzer functions.

OUTPUT 7 16 ; “CALCULATE : MARKER : MAXIMUM”

This sends the command within the quotes (CALCULATE : MARKER : MAXIMUM) to the

HP-II3

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.

l-6

HP-IB Requirements

Number of Devices:

Interconnection Path/Maximum Cable Length:

Message

Data

Address Capability:

Multiple Controller Capability:

Interconnected

Transfer

Rate:

Scheme:

15 maximum

20 meters maximum or 2 meters per device, whichever is less.

Byte serial/ bit parallel asynchronous data transfer using a

Maximum of 1 megabyte per second over

limited distances with tri-state drivers.

Actual data rate depends on the transfer rate of the slowest device involved.

Primary addresses: 31 talk, 31 listen. A

maximum of 1 talker and 14 listeners at one

time. 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.

3-line

handshake system.

l-7

Interface Capabilities

The analyzer has the following interface capabilities, as defined by the IEEE 488.1 standard:

SHl

AH1 T6

TEO

LEO

SRl

1 RLl

OCI

c2 c3

c4l

CB1

c122

full Source handshake capability full Acceptor handshake capability basic Talker, Serial Poll, no Talk Only, unaddress if MLA no Extended Talker capability basic Listener, no Listen Only, unaddress if MTA no Extended Listener capability

full Service Request capability

full Remote/local capability

full Device Clear caoabilitv

System Controller capability

send

IFC

and take charge Controller capability send REN Controller capability respond to send IFC, receive control, pass control, pass control to self send IF messages, receive control, pass control tri-state drivers

SRC

1-8

LIT1 PPO

only when an HP Instrument BASIC program is running

2 only when an HP Instrument BASIC program is not running

full device trigger capability no parallel poll capability

Programming Fundamentals

This section includes 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.

specific

information for programming your network

Controller Capabilities

The analyzer can be a talker/listener on the bus.

the System Controller or the

@YSTEM

The analyzer is not usually

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

conEgured

passed control it can function as the active controller.

0PrloNs)

as a talker/listener. In this

conEgured

‘Ib configure

HP-IB menu.

conEgured

as an

HP-IIl

the analyzer, select either

TalkerlListeaer

as the system controller unless it is the

conEguration,

system controller or as

softkey

when the analyzer is

in the

l-9

Introduction to

HP-IR

Programming

Programming Fundamentals

Response to Bus Management Commands

The HP-IB 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 HP-IB bus 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

Go To local

(DC11

(GTLI

Interface Clear

(IFC)

When the analyzer receives this command, it:

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:

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).

This command returns the analyzer to local (front-panel) control. All keys on the analyzer’s front-panel are enabled.

This command causes the analyzer to halt all bus activity. It discontinues any input or output, although the input and output queues are not cleared. If the analyzer is designated as the active controller when this command is received, it relinquishes control of the bus to the system controller. If the analyzer is enabled to respond to a Serial Poll it becomes Serial Poll disabled.

l-10

Introduction to

Programming Fundamentals

HP-16

Programming

local lockout

Parallel Poll

Remote Enable

(1101

(RENI

This command causes the analyzer to enter the local lockout mode, regardless of whether it is in the local or remote mode. The analyzer only leaves the

local lockout mode when the HP-IB’s Remote Enable (REN) line is set FALSE.

Local Lockout ensures that the analyzer’s remote

Rstunr ta LOCAL softkey)

is disabled when the analyzer is in the remote

softkey

menu (including the

mode. When the key is enabled, it allows a front-panel operator to return the

analyzer to local mode, enabling all other front-panel keys. When the key is disabled, it does not allow the front-panel operator to return the analyzer to local mode.

The analyzer ignores all of the following parallel poll commands:

Parallel Poll

Parallel Poll Enable (PPE).

Parallel Poll Disable (PPD).

REN is a single line on the

ConEgure

(PPC).

UnconEgure (PPU).

HP-IR.

When it is set TRUE, the analyzer will enter the remote mode when addressed to listen. It will remain in remote mode until it receives the Go to Local (GTL) command or until the REN line is set FALSE.

When the analyzer is in remote mode and local lockout mode, all front panel

keys are disabled. When the analyzer is in remote mode but not in local lockout mode, all front panel keys are disabled except for the softkeys. The remote softkey menu includes seven keys that are available for use by a

program. The eighth

softkey

is the

Bet-

to LOCAL key which allows a front-panel operator to return the analyzer to local mode, enabling all other front-panel keys.

l-11

Introduction to

HP-18

Programming

Programming Fundamentals

Selected Device Clear

(SDC)

Serial Poll

The analyzer responds to this command in the same way that it responds to the Device Clear (DCL) command.

When the analyzer receives this command it:

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:

Front-panel operation.

Any analyzer operations in progress (other than those already mentioned).

Any analyzer settings or registers (although clearing the output queue may

indirectly affect the Status Byte’s MAV bit).

The analyzer responds to both of the serial poll commands. The Serial Poll Enable (SPE) command causes the analyzer to enter the serial poll mode. While the analyzer is in this mode, it sends the contents of its Status Byte register to the controller when addressed to talk.

When the Status Byte is returned in response to a serial poll, bit 6 acts as the Request Service (RQS) bit. If the bit is set, it will be cleared after the Status Byte is returned.

The Serial Poll Disable (SPD) command causes the analyzer to leave the serial poll mode.

Take Control Talker

ITCTI

If the analyzer is addressed to talk, this command causes it to take control of the HP-IB. It becomes the active controller on the bus. The analyzer automatically passes control back when it completes the operation that required it to take control. Control is passed back to the address the

*PCB

command (which should be sent prior to passing control).

speciEed

If the analyzer does not require control when this command is received, it immediately passes control back.

1-12

Introduction to HP-IB Programming

Programming Fundamentals

Message Exchange

The analyzer communicates with the controller and other devices on the HP-IB using program messages and response messages. Program messages are used to send commands, queries, and data to the analyzer.

Response messages are used to return data from the analyzer. The syntax for both kinds of messages is discussed in Chapter 10.

There are two important things to remember about the message exchanges between the analyzer and other devices on the bus:

The analyzer only talks after it receives a terminated query (see “Query

Response Generation” later in this section).

Once it receives a terminated query, the analyzer expects to talk before it is

told to do something else.

HP-IB Queues

Queues enhance the exchange of messages between the analyzer and other devices on the bus. The analyzer contains:

An input queue.

An error queue.

An output queue.

Input Queue.

The input queue temporarily stores the following until they are read by the analyzer’s command parser:

Device commands and queries.

The HP-IB END message (EOI asserted while the last data byte is on the bus).

The input queue also makes it possible for a controller to send multiple program messages to the analyzer without regard to the amount of time required to parse and execute those messages. The queue holds up to

128 bytes. It is cleared when:

The analyzer is turned on.

The Device Clear (DCL) or Selected Device Clear (SDC) command is received.

1-13

Introduction to

HP-M

Programming

Programming Fundamentals

Error Queue.

The error queue temporarily stores up to 20 error messages. Each time the analyzer detects an error, it places a message in the queue. When you send the

SYST:ERR?

query, one message is moved from the error queue to the output queue so it can be read by the controller. Error messages are delivered to the output queue in the order they were received.

The error queue is cleared when:

All the error messages are read using the SYST : ERR? query.

The analyzer is turned on.

The *CLS command is received.

Output Queue.

The output queue temporarily stores a single response message until it is read by a controller. It is cleared when:

The message is read by a controller.

The analyzer is turned on.

The Device Clear (DCL) or Selected Device Clear (SDC) command is received.

Command Parser

The command parser reads program messages from the input queue in the order they were received from the bus. It analyzes the messages to determine what actions the analyzer should take.

One of the parser’s most important functions is to determine the position of a program message in the analyzer’s command tree (described in Chapter 10). When the command parser is reset, the next command it receives is expected to arise from the base of the analyzer’s command tree.

The parser is reset when:

The analyzer is turned on.

The Device Clear (DCL) or Selected Device Clear (SDC) command is

received.

A colon immediately follows a semicolon in a program message. (For more

information see “Sending Multiple Commands” in Chapter 10.)

A program message terminator is received. A program message terminator

can be an ASCII carriage return

(‘n)

newline

character or the HP-IS

END message (EOI set true).

1-14

Introduction to HP-IB Programming

Query Response Generation

When the analyzer parses a query, the response to that query is placed in the analyzer’s output queue. The response should be read immediately after

the query is sent. This ensures that the response is not cleared before it is read. The response is cleared when one of the following message exchange conditions occurs:

Unterminated condition - the query is not properly terminated with an ASCII carriage return character or the HP-IB END message (EOI set true) before the response is read.

Interrupted condition - a second program message is sent before the response to the

Buffer deadlock - a program message is sent that exceeds the length of the

first

is read.

input queue or that generates more response data than Ets in the output queue.

1-15

Introduction to HP-IB Programming

Synchronizing the Analyzer and a Controller

The IEEE 488.2 standard provides tools that can be used to synchronize the analyzer and a controller. Proper use of these tools ensures that the analyzer

is in a known state when you send a particular command or query.

Device commands can be divided into two broad classes:

Sequential commands.

Overlapped commands.

Most of the analyzer’s commands are processed sequentially. A sequential command holds off the processing of subsequent commands until it has been

completely processed. Some commands do not hold off the processing of subsequent commands;

they are called overlapped commands.

2-2

Overlapped Commands

Typically, overlapped commands takelongerto process than sequential commands. Forexample,the

measurement. The command is not considered to have been completely

processed until the measurement is complete. This a narrow or fine system bandwidth or when averaging is enabled.

The analyzer has the following overlapped commands:

ABORt

CALibration:ZERO:AUTO

CONFigure[ll21

DIAGnostic:CCONstants:LOAD DIAGnostic:CCONstants:STORe:DISK DIAGnostic:CCONstants:STORe:EEPRom DIAGnostic:DITHer DIAGnostic:SPUR:AVOid

HCOPy[:IMMediate]

INITiate[ll2]:CONTinuous INITiate[lI2][:IMMediate]

MMEMory:LOAD:STATe

OUTPut[:STATe] POWer[112l:MODE PROGram[:SELected]:EXECute ROUTE[ll2]:PATH:DEFine:PORT(foruse SENSeCll2l:AVERage:CLEar SENSeC112l:AVERage:COUNt SENSe[l I2l:AVERageC:STATel SENSe[ll2]:BWIDth[:RESolutionl SENSe[112]:CORRection:COLLect[:ACQuirel SENSe[1l2]:CORRection:COLLect:ISTate[:AUTOl SENSe[112]:CORRection:COLLect:METHod SENSe[ll2]:CORRection:COLLect:SAVE SENSe[ll2]:CORRection:CSET[:SELect] SENSe[ll2]:CORRection[:STATel

SENSe:COUPle

SENSe[ll21:DETector[:FUNCtionl SENSe[ll2]:DISTance:STARt(Option SENSe[ll2]:DISTance:STOP(Option

:INITIATE:IMMEDIATEcommandrestarts

can

take alongtime with

withmultiporttest sets)

100 only)

lOOonly)

2-3

Synchronizing the Analyzer and a Controller

Overlapped Commands

SENSeCl I2l:FREQuency:CENTer SENSe[ll2]:FREQuency:MODE(Option 100 only) SENSeCll21:FREQuency:SPAN SENSeCll21:FREQuency:SPAN:MAXimum SENSeCll21:FREQuency:STARt SENSeCll21:FREQuency:STOP SENSeCl

I2l:FUNCtion

SENSe[1121:FUNCtion:SRL:SCANC:IMMediate](Option lOOonly)

SENSe:ROSCillator:SOURce

SENSeCll2l:STATe SENSe[ll21:SWEep:POINts SENSe[ll2]:SWEep:TIME SENSe[112]:SWEep:TIME:AUTO

SENSe:SWEep:TRIGger:SOURce

SOURce[1l21:POWerC:LEVel]

[:IMMediate]

[:AMPLitude]

SYSTem:PRESet

TRACe[:DATA] TRIGger[:SEQuence]:SOURce

2-4

The NPO Flag

The analyzer uses a No Pending Operation (NPO) flag to keep track of overlapped commands. The NPO flag is reset to 0 when an overlapped command has not completed (still pending). It is set to 1 when no overlapped commands are pending. The NPO flag cannot be read directly but all of the following common commands take some action based on the setting of the flag.

*WA1

*0PC?

*0PC

Holds off the processing of subsequent commands until the NPO flag is set to 1. This ensures that commands in the analyzer’s input queue are processed in the order received.

The program continues to run, and additional commands are received and parsed by the analyzer (but not executed), while waiting for the NPO flag to be set. Use of the

*WA1

command is explained later in this section and is demonstrated in the SETUP example program.

Places a 1 in the analyzer’s output queue when the NPO flag is set to 1. lf the program is designed to read the output queue before it continues, this effectively pauses the controller until all pending overlapped commands are completed. Use of the *OPC? command is explained later in this chapter and is demonstrated in the TRANCAL and REFLCAL example programs.

Sets bit 0 of the Standard Event Status event register to 1 when the NPO flag is set to 1. The analyzer’s status registers can then be used to generate a service request when all pending overlapped commands are completed. This synchronizes the controller to the completion of an overlapped command, but also leaves the controller free to perform other tasks while the command is executing.

NOTE

*OPC

only informs you when the NPO flag is set to 1.

subsequent commands. No commands should be sent to the analyzer between sending the command and receiving the service request. Any command sent will be executed and may affect how the instrument responds to the previously sent

*OPC.

does not hold off the processing of

*OPC

2-5

Synchronizing the Analyzer and a Controller

The NPO Flag

CAUTION

The *CLS and

*RST

commands cancel any preceding

*OPC

command or query. Pending overlapped commands are still completed, but their completion is not reported in either the status register or the output queue. Two

HP-H3

bus management commands - Device Clear (DCL) and Selected

Device Clear (SDC) - also cancel any preceding *OPC command or query.

NOTE

Use

*WAI, *OPC?

is to send

ALWAYS

trigger an individual sweep (using *OPC? and waiting for the

*OPC?

*OPC

whenever overlapped commands are used. A recommended technique

at the end of each group of commands.

reply) before reading data over the bus or executing a marker function. The analyzer has the ability to process the commands it. receives faster than it can make a measurement,. lf the measurement is not complete when the data is read or a marker search function is executed the results are invalid.

The command to use (in an

OUTPUT

ENTER

QHp87ll;“ABOR;:INIT:CONT

OHp87ll;Opc-done

IBASIC

OUTPUT statement) is:

OFF;:INIT;*OPC?”

or another form of the : with the *OPC? query.

Refer to

“%king

Sweeps” in Chapter 6 for more information.

2-6

INITiate Cl I21 C:

IMMediateI command combined

WAl

Synchronizing the Analyzer

and a Controller

The NPO Flag

Usage of WA1 and OPC?

The following example describes the use of the discussion, remember that a sequential command holds off the processing of subsequent commands until it has been completely processed. An overlapped command does not.

*WA1

command. For this

10 OUTPUT QRfna; 20 OUTPUT

(PRf

“commandi”

na;

“command2

;

*WAI”

30 OUTPUT QRfna;“command3;”

40 OUTPUT

QRf

na;

“command4”

50 END

In the example above:

Commands 1 through 4 are sent to the analyzer as fast as the HP-IB bus traffic will allow, and the program may very well end before any command has been completed.

Command 1 begins execution first.

The order in which commands 1 and 2 are

completed

depends on the command types. If both commands are overlapped commands (versus

sequentid

Commands 3 and 4 will not be parsed until commands 1 and 2 are

commands), the order of completion is unknown.

completed.

Command 3 will begin execution before command 4.

The order in which commands 3 and 4 are

ccnnpktm

depends on the command types. If both commands are overlapped commands (versus sequential commands), the order of completion is unknown.

2-7

Synchronizing the Analyzer and a Controller

*oPc?

The following example describes the use of the *OPC? query and command. For this discussion, remember that a sequential command holds off the processing of subsequent commands until it has been completely processed. An overlapped command does not.

10 OUTPUT ORfna; 20 OUTPUT QRfna;

“commandi”

“command2; *OPC?”

30 ENTER ORfna;Opc-done 40 OUTPUT

50 OUTPUT QRfna;

(QRf

na;

“command3

“command4; *OPC?”

;

I’

60 ENTER ORfna;Opc-done

END

In the example above:

Commands 1 and 2 are sent to the analyzer as fast as the HP-IB bus traffic will allow.

Command 1 will begin execution before command 2.

The order in which commands 1 and 2 are

cowzpktm!

depends on the command types. If both commands are overlapped commands (versus sequential commands), the order of completion is unknown.

When commands 1 and 2 are completed, commands 3 and 4 will be sent to the analyzer as fast as the HP-IB bus

Command 3 will begin execution before command 4.

traffic

will allow.

The order in which commands 3 and 4 are

completed

depends on the command types. If both commands are overlapped commands (versus sequential commands), the order of completion is unknown.

This program will not end until the OPC in line 60 is returned.

2-8

Passing Control

When an external controller is connected to the analyzer with an HP-IB

cable, passing control may be needed to control devices such as printers and plotters that are also connected on the HP-IB. For some operations the active controller must pass control to the analyzer. When the analyzer completes the operation, it automatically passes control of the bus back to the external controller.

An example program, PASSCTRL, demonstrates passing control to the analyzer. In this example program control is passed so the analyzer can control a printer for hardcopy output. See Chapter 8, “Example Programs.”

NOTE

Pass Control is not needed to control peripherals connected to the serial, parallel, or LAN ports.

For smooth passing of control, take steps that ensure the following conditions are met:

The analyzer must know the controller’s address so it can pass control

back.

The controller must be informed when the analyzer passes control back.

3-2

Passing Control

The following is a procedure for passing control:

1. Send the controller’s HP-IB address to the analyzer with the *PCB command.

2. Clear the analyzer’s status registers with the

*CLS

command.

3. Enable the analyzer’s status registers to generate a service request when the Operation Complete bit is set. (Send

*ESE

with a value of 1 and *SRE

with a value of 32.)

4. Enable the controller to respond to the service request.

5. Send the command that requires control of the bus followed by the *OPC command.

6. Pass control to the analyzer and wait for the service request. The service request indicates that the command has been completed and control has

been passed back to the controller.

NOTE

For this procedure to work properly, only the command that requires control of the bus should be pending. Other overlapped commands should not. For more information on overlapped commands, see Chapter 2, “Synchronizing the Analyzer and a Controller.”

3-3

Passing Control

Data Types and Encoding

Data is transferred between the analyzer and a controller via the HP-IB data lines,

DIOl

through at a time), bit-parallel (8 bits at a time) manner. This section discusses the following aspects of data transfer:

The different data types used during data transfers.

Data encoding used during transfers of numeric block data.

DIOS.

Such transfers occur in a byte-serial (one byte

4-2

Data Types

The analyzer uses a number of different data types during data transfers. Data transfer occurs in response to a query. The data type used is determined

by the parameter being queried. The different parameter types are described

in the “Parameter Types” section of Chapter 10. Data types described in this section are:

Numeric Data.

Character Data

String Data

Expression Data

Block Data

Numeric Data

The analyzer returns three types of numeric data in response to queries:

NRl

data

Integers (such as + 1, response type for boolean parameters as

-1, 123, -12345). This is the

weII

as some

numeric parameters.

NR2

data

Floating point numbers with an explicit decimal point (such as 12.3, +1.234, -0.12345).

NR3

data

Floating point numbers in scientific notation (such as

+1.23E+5,

+123.4E-3,

-456.789E+6).

4-3

Data Types and Encoding

Data Types

Character Data

Character data consists of

that represent specific instrument settings (such as

MLOGarithmic).

mnemonic in upper-case alpha characters.

The analyzer always returns the short form of the

ASCII

characters grouped together in mnemonics

MAXimum

MINimum

String Data

String data consists of ASCII characters. The string must be enclosed by a delimiter, either single quotes (‘This is string data. ‘) or double quotes

(“This is also string data.

the string it must be typed twice without any characters in between. The analyzer always uses double quotes when it returns string data.

‘I).

To include the delimiter as a character in

Expression Data

Expression data consists of mathematical expressions that use character parameters. When expression data is sent to the analyzer it is always

enclosed in parentheses

returns expression data enclosed in double quotes.

(such

(IMPL/CHlSMEM)

(IMPL)).

The analyzer

4-4

Data Types and Encoding

Data Types

Block Data

Block data are typically used to transfer large quantities of related data (like a data trace). Blocks can be sent as blocks - the instrument will accept either form. The analyzer always returns definite length block data in response to queries.

deEnite

length blocks or indefinite length

Definite Block length

The general form for a

definite

block length transfer is:

#Q-mm-digits><num,bytes><data,bytes>

the definite length block, two numbers must be

decimal digit

<num,digits> speciEes

how many digits are contained in

<num,bytes>. The decimal number <num-bytes)

bytes will follow in <data-bytes>. An example statement to send ABC+XYZ as a

deEnite

block length parameter is shown,

specified.

speciEes

IBASIC

The single

how many data

(or HP BASIC)

note that the data block contains seven bytes (7) and only one digit is needed to describe the block length 1.

OUTPUT 716;

NOTE

This analyzer will send an additional definite length block form for your analyzer is:

“#17ABC+XYZ”

cc~>

with EOI asserted for definite block length transfers. The

#<num,digits><num,bytes><data-bytes><cn><EOI>

<num,bytes> is the number of <data-bytes> without counting

<Cn><EOI>.

4-5

Data Types and Encoding

Data Types

indefinite Block length

The general form for an indefinite block length transfer is:

After the last data byte is sent, the by sending a carriage return or termination of the program message. An example

statement to send ABC+XYZ as an

indehnite

newline

indeEnite

length block must be terminated

with EOI asserted. This forces the

IBASIC

(or HP BASIC)

block length parameter is shown,

note that ,END is used to properly terminate the message.

OUTPUT

716;

“#OABC+XYZ”

,END

4-6

Data Encoding for Large Data Transfers

The

FORMat :DATA

encoding that is used to transfer large blocks of numeric data between the analyzer and a controller. There are two specifiers:

command selects the type of data and the type of data

REAL

INTeger

ASCii

Blocks that contain mixed data - both numbers and ignore the setting of definite length or indefinite length block data. The following commands transfer blocks of mixed data:

PROGram[:SELectedl :DEFine

SYSTem:SET

specifies the block data type. Either the definite or indefinite length syntax can be used. The block is transferred as a series of binary-encoded floating-point numbers. Data transfers of the REAL, 64 data type are demonstrated in the

REALDATA

specifies the block data type. Either the

length syntax can be used. The block is transferred as an

array of binary-encoded data with each point represented by a set of three internal format- it should only be used for data that will be returned to the instrument for later use. Data transfers of the and LOADCALS example programs.

specifies

The data is transferred as a series of

separated by commas. ASCii formatted data transfers are

demonstrated in the ASCDATA example program.

example program.

16-bit

INTeger,

FORMat :DATA.

16 data type are demonstrated in the INTDATA

the numeric data type

These blocks always transfer as either

detiite

integers. This is the instrument’s

(NRl, NR2

ASCX-encoded

ASCII

or indefinite

NR3

syntax).

numbers

characters

4-7

Data Types and Encoding

Data Encoding for large Data Transfers

ASCII Encoding

The ANSI

X3.4-1977

standard

dehnes

the ASCII

7-bit

code. When an ASCII-encoded byte is sent over the HP-IB, bits 0 through 6 of the byte (bit 0 being the least through

D107. D108

signihcant

is ignored.

bit) correspond to the HP-IB data lines

DIOl

When ASCII encoding is used for large blocks of data, the number of significant digits to be returned for each number in the block can be For example, the following command returns all numbers as

NR3

specitied.

data with 7

significant digits.

FORMat:DATA

ASCii,7

Binary Encoding

When binary encoding is used for large blocks of data, all numbers in the block are transferred as

an array of

16-bit

the IEEE 754-1985 standard.

FORMat:DATA FORMat:DATA

FORMat

: DATA

32-bit

64-bit

binary floating point numbers or as

integers. The binary floating-point formats are defined in

REAL,32 REAL,64

INTeger ,16

selects the IEEE

ported by

selects the IEEE

selects the

BASIC

16&t

32&t format

or HP BASIC).

64&t

format.

integer format.

(not sup-

4-8

Data Types and Encoding

Byte Swapping

PC compatibles frequently use a modification of the IEEE floating point formats with the byte order reversed. To reverse the byte order for data transfer into a PC, the

FORMat :BORDer

command should be used.

FORMat FORMat

BORDer SWAPped

BORDer NORMal

selects the byte-swapped format selects the standard format

4-9

Data Types and Encoding

Using Status Registers

The analyzer’s status registers contain information about the condition of the

network analyzer and its measurements. This section describes the registers

and their use in Example programs using the status registers are included in Chapter 8,

“Example Programs. ’These programs include use service request interrupt routines, PASSCTRL which uses the status byte to request control of the condition register.

HP-lB

programming.

HP-lB

SRQ

and GRAPHICS which

and LIMITEST which uses the Limit Fail

5-2

Bit Weights

16 32 64 128 256 512

1.024

2.048 4,096

8,192

16.384 32,768

General Status Register Model

The analyzer’s status system is based on the general status register model shown in Figure 5-l. Most of the analyzer’s register sets include all of the registers shown in the model, although commands are not always available for reading or writing a particular register. The information flow within a register set starts at the condition register and ends at the register summary bit (see Figure 5-2). This flow is controlled by setting bits in the transition and enable registers.

Two register sets - the Status Byte and the Standard Event Status Register - are S-bits wide. All others are

signihcant

bit (bit 15) in the larger registers is always set to 0.

Condition

STATus:<mnemonw:CONDltion?

Posltlve Transltlon Filter ( STATus:<mnemonlo:PTRansltlon

Negative

Transltlon Filter ( STATus:<mnemonlc>:NTRansltlon )

condition

Bit

condltton

Bit 1

condltlon

Bit 2

Bit

16-bits

Event Register (

Enable

wide, but the most

)

STATus:<mnemonic>l:EVENtl? )

>-+

To Summary Bit

Figure

5-l.

General Status Register Model

5-3

Using Status Registers

General Status Register Model

Condition Register

Condition registers continuously monitor the instrument’s hardware and firmware status. Bits in a condition register are not latched or buffered, they

are updated in real time. When the condition monitored by a specific bit becomes true, the bit is set to 1. When the condition becomes false the bit is reset to 0. Condition registers are read-only.

Transition Registers

Transition registers control what type of change in a condition register will set the corresponding bit in the event register. Positive state transitions (0 to 1) are only reported to the event register if the corresponding positive transition bit is set to 1. Negative state transitions (1 to 0) are only reported if the corresponding negative transition bit is set to 1. Setting both transition bits to 1 causes both positive and negative changes to be reported. Transition registers are read-write, and are unaffected by They are reset to instrument default conditions at power up and after *RST and

SYSTem

PRESet

commands.

*CLS

(clear status) or queries.

Event Register

Event registers latch any reported condition changes. When a transition bit allows a condition change to be reported, the corresponding event bit is set to 1. Once set, an event bit is no longer affected by condition changes. It remains set until the event register is cleared. Event registers are read-only.

An event register is cleared when you read it. All event registers are cleared when you send the

5-4

*CLS

(clear status) command.

Using Status Registers

General Status Register Model

Enable Register

Enable registers control the reporting of events (latched conditions) to the register summary bit. If an enable bit is set to 1 the corresponding event is included in the logical summary bit. (The summary bit is only set to 1 if one or more enabled event bits are set to 1.) Summary bits are recorded in the instrument’s status byte. Enable registers are read-write and are cleared by

Positive

Transition

ORing

process that determines the state of the

*CLS

(clear status).

Condition

I-

Negative

Transitton

Enable

tvent

AND

Note:

The Event Register remains set until it is read or the

*CLS

command is sent.

Figure 5-2. Flow of information within a register set

5-5

How to Use Registers

There are two methods of accessing the information in status registers:

The direct-read method.

The service request (SRQ) method

In the direct-read method the analyzer is passive. It only tells the controller that conditions have changed when the controller asks the right question. In the SRQ method, the analyzer is more active. It tells the controller when there has been a condition change without the controller asking. Either method allows you to monitor one or more conditions.

The following steps are used to monitor a condition with the direct read method:

1. Determine which register contains the bit that monitors the condition.

2. Send the unique

HP-IS

query that reads that register.

3. Examine the bit to see if the condition has changed. The direct-read method works well when it is not necessary to know

about changes the moment they occur. It does not work well if immediate knowledge of the condition change is needed. A program that used this

method to detect a change in a condition would need to continuously read the registers at very short intervals. The SRQ method is better suited for that type of need.

5-6

The Service Request Process

The following steps are used to monitor a condition with the SRQ method:

1. Determine which bit monitors the condition.

2. Determine how that bit reports to the request service (RQS) bit of the Status Byte.

3. Send HP-IB commands to enable the bit that monitors the condition and to enable the summary bits that report the condition to the RQS bit.

4. Enable the controller to respond to service requests.

When the condition changes, the analyzer sets its RQS bit and the HP-IB’s

SRQ line. The controller is informed of the change as soon as it occurs. The tune the controller would otherwise have used to monitor the condition can now be used to perform other tasks. The controller’s response to the SRQ is determined by the program being run.

Using Status Registers

The Service Request Process

The process of preparing the analyzer to generate a service request, and the handling of that interrupt when it is received by a program, are demonstrated in the SRQ example program.

When a register set causes its summary bit in the Status Byte to change from

0 to 1, the analyzer can initiate the service request (SRQ) process. If both the

following conditions are true the process is initiated:

The corresponding bit of the Service Request enable register is also set to 1.

The analyzer does not have a service request pending. (A service request is considered to be pending between the time the analyzer’s SRQ process is initiated and the time the controller reads the Status Byte register with a serial poll

The SRQ process sets the

HP-IB’s

SRQ line true and sets the Status Byte’s request service (RQS) bit to 1. Both actions are necessary to inform the controller that the analyzer requires service. Setting the SRQ line informs the controller that some device on the bus requires service. Setting the RQS bit allows the controller to determine that the analyzer was the device that initiated the request.

When a program enables a controller to detect and respond to service requests, it should instruct the controller to perform a serial poll when the HP-IB’s SRQ line is set true. Each device on the bus returns the contents of its Status Byte register in response to this poll. The device whose RQS bit is set to 1 is the device that requested service.

NOTE

When the analyzer’s Status Byte is read with a serial poll, the RCIS bit is reset to 0. Other bits in the register are not affected.

As implied in Figure 5-3, bit 6 of the Status Byte register serves two functions; the request service function (RQS) and the master summary status function (MSS). Two different methods for reading the register allow you to access the two functions. Reading the register with a serial poll allows you to access the bit’s RQS function. Reading the register with

*STB

allows you to

access the bit’s MSS function.

5-9

The Analyzer’s Status Register Sets

The analyzer uses eight register sets to keep track of instrument status: Status Byte Device Status Limit Fail Questionable Status

Standard Event Status Measuring Status Averaging Status

Operational Status

*STB? and*SRE

STATus:DEVice

STATus:QUEStionable:LIMit

STATus:QUEStionable

*ESR?

and

*ESE

STATus:OPERation:MEASuring STATus:OPERation:AVERaging STATus:OPERation

Their reporting structure is summarized in Figure 5-4. They are described in greater detail in the following section.

NOTE

Register bits not explicitly presented in the following sections are not used by the analyzer. A query to one of these bits returns a value of 0.

5-10

Device Status

Using Status Registers

The Analyzer’s Status Register Sets

Standard Event Status Register

Measuring

Limit Fall

Questionable Status

Output Queue ,

Figure 5-4. Analyzer Register Sets

Status

B&e

5-11

Bit Weights

Using Status Registers

The Analyzer’s Status Register Sets

Status Byte

The Status Byte register set summarizes the states of the other register sets

and monitors the analyzer’s output queue. It is also responsible for generating

service requests (see “Generating a Service Request” earlier in this chapter).

See Figure 5-5.

serial poll (bit 6 - Request Service)

*SIB?

(bit 6 Master Summary Status)

Device Status Summary

Questionable

Request Service/Master Summary Status

OperatIonal

Status Summary

Message Available

Standard Event Summary

Status Summary

r-z

Figure 5-5. The Status Byte Register Set

The Status Byte register set does not conform to the general status register model described at the beginning of this chapter. It contains only two registers: the Status Byte register and the Service Request enable register. The Status Byte register behaves like a condition register for all bits except bit 6. The Service Request enable register behaves like a standard enable register except that bit 6 is always set to 0.

5-12

Using Status Registers

The Analyzer’s Status Register Sets

Bits in the Status Byte register are set to 1 under the following conditions:

Device

Questionable

Status

Summary (bit 2) is set to 1 when one or more enabled

Summary

Message Available

Standard Event Status

Summary

Master Summary Status

Request Service

Operational

Status

Summary

bits in the Device Status event register are set to 1.

(bit 3) is set to 1 when one or more enabled bits in the Questionable Status event register are set to 1.

(bit 4) is set to 1 when the output queue contains a response message.

(bit 5) is set to 1 when one or more enabled bits in the Standard Event Status event register are set to 1.

(bit 6, when read by

*STB)

is set to 1 when one or more enabled bits in the Status Byte register are set to 1.

(bit 6, when read by serial poll) is set to 1 by the service request process (see

“Generating a Service Request” earlier in

this chapter).

(bit 7) is set to 1 when one or more enabled bits in the Operational Status event register

are set to 1.

5-13

Using Status Registers

The Analyzer’s Status Register Sets

The commands used to read and write the Status Byte registers are listed

below :

SPOLL

*STB?

*SRE <num>

*SRE?

IBASIC

(or HP BASIC) command used in the service request process to determine which device on the bus is requesting service.

reads the value of the instrument’s status byte. This is a non-destructive read, the Status Byte is cleared by the *CLS command.

sets bits in the Service Request Enable register. The current setting of the Service Request Enable register is stored in non-volatile memory. If *PSC has been set, it will be saved at power on.

reads the current state of the Service Request Enable register.

5-14

Using Status Registers

The Analyzer’s Status Register Sets

Device Status Register Set

The Device Status register set monitors the state of device-specific

parameters. Bits in the Device Status condition register are set to 1 under the following

conditions: Key Pressed

Any

Softkey

Pressed Any

External

Keyboard Key Pressed

Front Knob Turned

Panel

(bit 0) is set to 1 when one of the analyzer’s front panel keys has been pressed.

(bit 1) is set to 1 when one of the analyzer’s been pressed.

(bit 2)

external keyboard connected to the DIN KEYBOARD connector on the rear panel of the analyzer.

(bit 3) is set to 1 when the analyzer’s front panel knob is

turned.

is set to 1 when a key has been pressed on an

softkeys

has

5-15

Using Status Registers

The Analyzer’s Status Register Sets

Limit Fail Register Set

The Limit Fail register set monitors limit test results for both measurement

channels. Bits in the Limit Fail condition register are set to 1 under the following

conditions (refer also to Figure 5-6.)

Measurement Channel 1 Limit Failed

Measurement Channel 2 Limit Failed

Measurement Channel 1 Marker Limit Failed

Measurement Channel 2 Marker Limit Failed

(bit 0) is set to 1 when limit testing is enabled and any point on measurement channel 1 fails the limit test, or when any enabled marker limit on measurement channel 1 has failed.

(bit 1) is set to 1 when limit testing is enabled and any point on measurement channel 2 fails the limit test, or when any enabled marker limit on measurement channel 2 has failed.

(bit 2) is set to 1 when any enabled marker limit on measurement channel 1 has failed.

(bit 3) is set to 1 when any enabled marker limit on measurement channel 2 has failed.

5-16

Using Status Registers

The Analyzer’s Status Register Sets

5-18

Using Status Registers

The Analyzer’s Status Register Sets

Questionable Status Register Set

The Questionable Status register set monitors conditions that affect the quality of measurement data.

Bits in the Questionable Status condition register are set to 1 under the following conditions:

Limit Fail

Data Questionable

(bit 9) is set to 1 when one or more enabled bits in the Limit Fail event register are set to 1.

(bit 10) is set to 1 when a change in the analyzer’s configuration requires that new measurement data be taken.

5-19

Bit Wetghts

Using Status Registers

The Analyzer’s Status Register Sets

Standard Event Status Register Set

The Standard Event Status register set monitors HP-B errors and synchronization conditions. See Figure 5-7.

Operation Complete

Request Control

Dewce

Query Error

Dependent Error

Execution

Error

Command Error

User Request

Power On

Status

Bit

Byte

Figure 5-7. The Standard Event Status Register Set

The Standard Event Status register set does not conform to the general status register model described at the beginning of this section. It contains only two registers: the Standard Event Status event register and the Standard Event Status enable register. The Standard Event Status event register is similar to other event registers, but behaves like a register set that has a positive transition register with all bits set to 1. The Standard Event Status enable register is the same as other enable registers.

Operation Complete

(bit 0) is set to one when the following two events occur

(in the order listed):

The *OPC command is sent to the analyzer.

The analyzer completes all pending overlapped

commands.

5-20

Using Status Registers

The Analyzer’s Status Register Sets

Request Control

(bit 1) .

set to 1 when both of the following conditions

are true:

The analyzer is configured as a talker/listener for

HP-B

operation.

The analyzer is instructed to do something (such as plotting or printing) that requires it to take control of the bus.

Query Error

(bit 2) is set when the command parser detects a query error. A query error indicates:

1. an attempt to read data from the Output Queue when no data was present.

2. that data in the Output Queue was lost. An example of this would be queue overflow.

Device Dependent (bit 3) is set to 1 when the command parser detects a Error

device-dependent error. A device-dependent error is any analyzer operation that did not execute properly due to some internal condition such as over-range. This bit indicates that the error was not a command, query, or an execution error.

Execution Error

(bit 4) is set to 1

when the command parser detects an

execution error. Execution errors occur when:

Command Error

1. a <PROGRAM DATA> element received in a command was outside the legal range for the analyzer, or inconsistent with the operation of the analyzer.

2. the analyzer could not execute a valid command due to some analyzer condition.

(bit 5) is set to 1 when the command parser detects a command error. The following events cause a command error:

1. An IEEE 488.2 syntax error. This means that the analyzer received a message that did not follow the syntax defined by the 488.2 standard.

2. A semantic error occurred. For example, the analyzer received an incorrectly spelled command. Another

5-21

Using Status Registers

The Analyzer’s Status Register Sets

example would be that the analyzer received an

optional 488.2 command that it does not implement. Power On (bit 7) is set to 1 when you turn on the analyzer. The commands used to read and write the Standard Event Status registers are

listed below:

*ESR?

*ESE

<mm>

*ESE?

reads the value of the standard event status register. sets bits in the standard event status enable register. The

current setting of the standard event statue enable register is stored in non-volatile memory. If *PSC has been set, it will be saved at power on.

reads the current state of the standard event status enable register.

5-22

Using Status Registers

The Analyzer’s Status Register Sets

Measuring Status Register Set

The Measuring Status register set monitors conditions in the analyzer’s

measurement process.

Bits in the Measuring Status condition register are set to 1 under the following conditions:

Channel 1 Measuring

Channel 2 Measuring

(bit 0) is set to 1 while the analyzer is collecting measurement data on channel 1.

(bit 1) is set to 1 while the analyzer is collecting measurement data on channel 2.

Averaging Status Register Set

The Averaging Status register set monitors conditions in the analyzer’s

measurement process when the trace averaging function is in use. Bits in the Averaging Status condition register are set to 1 under the following

conditions :

Measurement Channel

1 Averaging

Measurement Channel 2 Averaging

(bit 0) is set to 1 while the analyzer is sweeping on measurement channel 1 and the number of sweeps completed (since “average restart”) is less than the averaging factor.

(bit 1) is set to 1 while the analyzer is sweeping on measurement channel 2 and the number of sweeps completed (since “average restart”) is less than the averaging factor.

5-23

Using Status Registers

The Analyzer’s Status Register Sets

Operational Status Register Set

The Operation Status register set monitors conditions in the analyzer’s measurement process, disk operations, and printing/plotting operations. It

also

monitors the state of the current HP Instrument BASIC program.

Bits in the Operational Status condition register are set to 1 under the following conditions:

Calibrating (bit 0) is set to 1 while the instrument is zeroing the

broadband diode detectors.

Settling

Measuring

Correcting

Averaging

Hardcopy Running

Test Running

Program Running

(bit 1) is set to 1 while the measurement hardware is settling.

(bit 4) is set to 1 when one or more enabled bits in the Measuring Status event register are set to 1.

(bit 7) is set to 1 while the analyzer is performing a calibration function.

(bit 8) is set to 1 when one or more enabled bits in the Averaging Status event register are set to 1.

(bit 9) is set to 1 while the analyzer is performing a hardcopy (print or plot) function.

(bit 10) is set to 1 when one of the analyzer’s internal service tests is being run.

(bit 14) is set to 1 while an HP Instrument BASIC program is running on the analyzer’s internal controller.

5-24

STATus:PRESet Settings

Using Status Registers

The Analyzer’s Status Register Sets

Executing the STATUS : (ENAB), positive transition (PTR) and negative transition (NTR) registers. The

table below shows the settings after the command is executed.

Resister Set

STATus:DEVice

STATus:qUEStionable:LIMit STATus:CjUEStionable STATus:OPERation:MEASuring

STATus:OPERation:AVERaging STATus:OPERation

PRESet

command changes the settings in the enable

ENABle

all

all is all

PTRansition

all is all

all

NTRansition

all

all is all

5-25

Using Status Registers

Analyzer Register Set Summary

Device Status

See Figure

---------_---------_ I@

Measl

1 I I Meosl Mkr

I hteosz I I

I I L-----------------

Device-Dependent Error

Limit

Meas

Limit Foil

Limit

Mkr

Limit Foil

Operation

Request Control

Query

Execution Error

Canmand

user Request

Power on

Meas, Measuring Meas* Measuring

Meas, SRL

Meas

SRL Scan

Fail

Standard Event

Status Reqister

Carydets

Error

Scan

5-6

Limit Fai I

Fail

WI!

Measur i ng

Averaging

Questionable

Status

CaIibro,ing

Output Queue

ODer

a i

Srarus

ona I

5-26

cd62c

Figure 5-8. Analyzer Register Set Summary

Trace Data Transfers

This chapter explains how to read (query) the measurement data trace from the analyzer into your program. It also describes how to send data from your program to the analyzer’s measurement arrays. Accessing the measurement

arrays is done using SCPI commands. If you are using you can also access the measurement arrays using high-speed subroutines. Refer to the

HP Instrument BASIC User’s Handbook

Figure 6-l is a data processing flow diagram that represents the flow of numerical data. The data passes through several math operations, denoted in the figure by single-line boxes. Most of these operations can be selected and controlled with the front panel CONFIGURE block menus.

in arrays along places in

the

way, denoted by double-line boxes. These

flow

path where data is

accessible

single flow path is shown, two identical paths are available, corresponding to measurement channels 1 and 2.

IBASIC

(Option

for more details.

The data is stored

via

HP-IB. While only a

lC2),

arrays are

Raw Data

A,B,R...

1-I

Ratio

6-2

Figure

Averaqlng

Error

Coefficient

Arrays

6-l.

Numeric Data Flow Through the Network Analyzer

Data Trace Memory Trace

cs650

Querying the Measurement Trace Using BASIC

After making a measurement, you can read the resultant measurement trace out of the analyzer using the SCPI query

“TRACE : DATA? CHIFDATA”

The BASIC program segment below shows how to read the trace from the

analyzer into an array in your program.

REAL

Trace(l:201)

ASSIGN

20 30

50 60 70

! Take sweep here OUTPUT OUTPUT

ENTER DISP Trace(l)

QHp8711

QHp871l;“FORM:DATA ASCII,5”

@Hp871l;“TRACE:DATA? CHlFDATA”

OHp87ll;Trace(*)

TO 716

,Trace(2) ,Trace(3)

,‘I. . .

.I’

In this program, the TRACE:DATA? query returns points as a single block. The analyzer computes the using the measurement format selected by the [FORMAT] menu (CALC:FORM SCPI command), and returns a block of data The values of each point correspond to the values displayed on the screen, or those shown in the marker readouts. The frequency stimulus value (X-axis) of each point is not returned by the TRACE:DATA? query; only the measurement response (Y-axis) values are returned.

When transferring the block of trace data, you may select either binary or ASCII data encoding. This is explained in Chapter 4 in the section titled

“Data Encoding for Large Data Transfers.” Notice that the terms “encoding format” and “measurement format” are not the same. The encoding format determines how the numbers are represented as bytes, while the measurement format corresponds to the meaning of the

The easiest way to transfer a measurement data trace is to use ASCII data encoding.

In the example above, the array Trace(l:201) contains 201 numbers. The SCPI command encoding, with 5 significant digits. The command “TRACE : DATA? instructs the analyzer to send the measurement trace. The ENTER statement reads the measurement data sent by the analyzer into the

“FORM:DATA

ASCII

all

of the measurement

value

for each point

called

the formatted data array.

value

of the numbers.

real

(floating point)

,5”

specifies ASCII data

Trace(l:201)

CHIFDATA”

array.

6-3

Trace Data Transfers

Querying the Measurement Trace Using BASIC

It is important to make sure that the Trace array declared in your program is the same size as the measurement trace on the analyzer, or an error will occur. The ENTER statement attempts to read data from the analyzer until

it completely

fills

the Trace array, at which point it expects to receive a

end-of-data terminator from the analyzer. To be safe, your program should

use the

“SENS

: SWE

:POIN”

SCPI command to set the number of measurement

data points to the desired value.

Refer to the example program ASCDATA in Chapter 8 for a complete example.

@Smith Chart and Polar Formats

Each measurement point is represented by a single floating point number. This is the case for all of the analyzer’s measurement formats except Smith Chart and Polar in the HP format is selected, each point is represented by two numbers, the first one being the real portion and the second being the imaginary portion of the complex measurement value.

8712C

and

8714C.

When Smith Chart or Polar

20 30

50 60 70

Below is a modified example program that will work when using Smith Chart or Polar formats.

REAL

Trace(l:201,1:2)

ASSIGN

QHp8711

TO 716

! Take sweep here OUTPUT OUTPUT

ENTER DISP

6-4

QHp8711;“FORM:DATA ASCII,5” QHp8711;“TRACE:DATA? CHIFDATA”

OHp87ll;Trace(*)

Trace(l,l),Trace(l,2),“.

indicates HP

8712C114C

.“,Trace(201,1),Trace(201,2)

only

Querying the Measurement Trace Using SICL

This section includes a complete SICL C program that shows how to read the measurement trace from the analyzer.

/**************************************************************************

This

program takes a sweep, reads the trace, and prints it.

It uses SICL (Standard Instrument Control Library) to talk

to the analyzer over HP-IB.

On HP-UX, compile using:

**************************************************************************/

#include #include

int

(

<sicl.h> Cstdio.h>

main(void)

INST analyzer; float int num-trace-bytes; int pt;

data-bufCl601);

/* /*

-Aa -0

For For

Handle used to talk to analyzer

measurement trace.

query-trace

iopen(), iprintf0, iscanfo, INST,

printfo */

query,trace.c -1sicl

32-bit

floats

-*-

num-trace-bytes

Open the network analyzer at address 16

analyzer

Clear the bus

iclear(analyzer1;

Abort current sweep and put analyzer sweep in hold iprintf(analyzer,

iprintf(analyzer,

Take one sweep, iprintf(analyzer, iprintf(analyzer,

= iopen("hpib,l6");

sizeof(data-buf);

"ABORT\n");

“INIT

: CONT

wait until done

"INITl\n"); "*OPC?\n");

OFF\n”)

Set to max allowable bytes

;

6-5

Trace Data Transfers

Querying the Measurement Trace Using

iscanf(analyzer, "(/l*s");

Request the trace data in

iprintfcanalyzer, iprintfcanalyzer,

"FORM:BORD NORM\n"); "FORM:DATA REAL,32\n");

32-bit

SIC1

floating point format

Query the trace,

iprintfcanalyzer,

read into data-buf

"TRAC? CHlFDATA\n");

iscanf(analyzer, "%#bX*c", &mm-trace-bytes, /*

Print the trace values.

for (pt

printf("X4d

= 0; pt <

mm-trace-bytes/sizeof(float);

%g\n" ,

pt,

data-buf[ptl);

1 /*

Close analyzer and exit.

*/ iclose(analyzer);

return 0;

Cl.

&data-buf

pt++) (

COl>;

6-6

Using Binary Data Encoding

The previous section describes how to query the measurement trace, and transfer it into your program using used for faster data transfers, as shown in the table below:

Table

6-l.

Typical Trace Transfer Times (ms)

When using binary data transfers, the entire trace is sent from the analyzer

to your program in a block called a definite length block. The details of block data are described in detail in Chapter 4. The header and a data section. The header indicates how many bytes are in the data section.

ASCII

encoding. Binary encoding can be

Points

Binary

21 23 30 62

delinite

length block contains a

order to read the

delinite

length block, your program must first read the header, and then read the data section. Refer to the example program

REALDATA

In the

in Chapter 8 for an example of how to do this.

REALDATA

program, you will notice the following lines which read the

definite block header:

180 190

ENTER ENTER

QHp8711 QHp8711

USING USING

“%,A,D”;A$,Digits “%,“&VAL$(Digits)&“D” ;Bytes

and these lines which read the data section:

200 210

ASSIGN ENTER

OHp87ll;Datal(*)

QHp8711;FORMAT

OFF

6-7

Trace Data Transfers

Using Binary Data Encoding

Each measurement point in the data section is represented as 4 or 8 bytes (32 or 64 bits), depending on whether single precision or double precision numbers are requested. When using HP BASIC or

IBASIC,

you must select double precision numbers to match BASIC’s “REAL” data type. Do this using the SCPI command “FORM : DATA REAL,

64”.

If you are using another

language that supports single precision data types, you can select single

precision using the SCPI command “FORM : DATA REAL, as

QuickBASIC

and C have support for both single and double precision

32”.

Languages such

floating point numbers. When transferring data using binary encoding, you may need to reverse

the order of the bytes in each measurement point, since PCs frequently store IEEE floating point numbers with the byte order reversed. To instruct the analyzer to reverse the byte order of the data, send the command

“FORMAT:BORDer SWAPped”

before querying the trace data.

6-8

Trace Data Transfers

Using Binary Data Encoding

Trace Data Transfer Sizes

The following table shows how many bytes are transmitted during trace

data transfers. The left column shows the format of the data, which you can

specify using the SCPI command Format : DATA. As you can see, the size of the measurement point data and trace data varies as you change format.

Table 6-2. Size of Trace Data Transfers (in Bytes) Using the

Format Type

(FORMat:DATA)

REAL.32

REAL,64

ASCII,5 ASCII,3

INT,16

When transmitting data in “REAL” or “INT” format, a header is sent before

the data block. The header indicates the size of the data block. The header size varies in length from 3 to 11 bytes. Refer to Chapter 4 for details on the header.

Transmitting ASCII data requires no header. The ASCII values are separated

by commas, and a

table include the size of the comma(s) and terminating linefeed. Typical data

ASCII,5

Type of Data

IEEE

32-bit

Floating Point IEEE

64-bit

Floating Point ASCII numbers ASCII numbers Internal Binary

format:

Single Measurement Point

Real

13 11

linefeed

is sent after the last value. The sizes shown in the

Complex

TRACESIATA SCPI

201 Point Trace

1614

2613 2211

Command

-1.2254E+000,+5.0035E-001,+4.5226E-OOl,...

The analyzer stores its internal data with approximately 5 of resolution. Using for data transfers. However,

REAL,32

ASCII,5

REAL,64

format provides sufficient precision

may be necessary when using a

programming language which does not support IEEE

signitlcant

32-bit

floating point.

digits

6-9

Transferring Data with

IBASIC

If you are using BASIC, your

BASIC

program can avoid the overhead of using OUTPUT and ENTER to transfer trace data, and instead use the analyzer’s built-in high-speed subprograms. These built-in subroutines let you quickly move data between the analyzer’s measurement arrays and your program’s data arrays. For example, to read the array, use the

10 DIM 20 INTEGER 30

LOADSUH

Read-fdata(Chan,Fmt(*))

Refer to the The table below compares the speed of

foIIowing:

Fmt(l:201)

Ghan

Read-f data FROM

“XFER:

Chan=l

HP Instrument BASIC User’s Handbook

IBASIC

anaIyzer’s

formatted data

MEM 0,O”

for more details.

using high-speed transfer subroutines with that of a fast external controller using the SCPI TRACE:DATA?

Number of Points

CHlFDATAquery.

Table 6-3. Typical Trace Transfer Times (msl

Controller Using Binary

5151 201201 401401

TRACE : DATA?

2121 77 2323 IOIO 3030 1313

1 IBASIC

Using

Read-f data

6-10

16011601

8282 3232

T&king

When making measurements and querying traces, your program should perform the following steps:

1. Place the analyzer’s sweep in hold

2. Initiate a single sweep

3. Wait for the sweep to complete

4. Query the measurement trace

Use the following program lines perform these steps:

Sweeps

10 OUTPUT 20 OUTPUT 30 OUTPUT 35 ENTER

40 OUTPUT 45 ENTER QHp8711;Fmt(*)

If you query the measurement trace while the analyzer is in continuous sweep, the query will still work, but the data may not be correct. Using and *OPC? ensures that a complete sweep has finished before you query the measurement data. In many cases, you can also use the command place of the

30 OUTPUT

However, there are cases where case is when using

“*WAI”

executed until the commands before the subprograms don’t use SCPI commands to access the trace data, ineffective, and

When using until the previous SCPI commands are complete, preventing your program from executing beyond the ENTER statement. When using program can continue to run and send SCPI commands, and the analyzer

buffer them and act upon them in order.

only ensures that the SCPI commands following the

QHp8711;“ABORT;:INITl:CONT QHp8711; “INITl” OHp8711; “*OPC?”

OHp8711;Opc

QHp8711;

“*OPC?”

OHp8711; “*WAI”

“*OPC?”

“*OPC?“,

“TRACE : DATA?

query, replacing lines 30 and 35 above with:

“*WAI”

IBASIC’s

high-speed subprograms to query the trace data.

should be used.

the ENTER statement following the

will produce incorrect results. One

“*WAI”

OFF”

CHlFDATA”

are complete. Since

“*WAI”

“*OPC?”

“*WAI”,

INIT

“*WAY

are not

IBASIC

will wait

your

will

For more details, refer to Chapter 2, “Synchronizing the Analyzer and a Controller.

”

6-11

CALC:DATA? versus TRACE:DATA?

The SCPI command command “TRACE : DATA?

for trace queries of the formatted measurement data. The

command is more flexible, allowing you to query other measurement arrays and to download data to measurement arrays.

“CALCl

: DATA?” is functionally equivalent to the

CHIFDATA”

. The two can be used interchangeably

“TRACE:DATA”

6-12

Querying Single Data Points Using Markers

Ifyouonlyneedto query instead ofatrace query The program segment below shows how to do this using the

10 20

30 40 50 60 70

Youcanalsousethe CALC:MARK:FUNC:RES?querytoreturntheresuits

bandwidth search. For example:

10 20 30 40 50

For more information on using markers, refer to Chapter 8, “Example Programs."

SCPIcommand

ASSIGN

! Take sweep here OUTPUT OUTPUT OUTPUT

ENTER DISP Marker-y

QHp8711

OHp871l;"CALCl:MARK QHp871l;"CALCl:MARKl:X OHp87ll;"CALCl:MARKl:Y?"

OHp87ll;Marker,y

! Select -3 dB bandwidth

OUTPUT

! Get result of bandwidth search OUTPUT ENTER

OHp87ll;Bwidth,Center,freq,Q,Loss

asingle

CALC:MARK.

TO 716

QHp871l;"CALC:MARK:BWID

QHp8711;

data point,

ON"

"CALC:MARK:FUNC:RES?"

youcan

! turn on marker

177 MHz"

-3"

use amarkerquery

! set frequency ! read marker

ofa

6-13

Accessing Other Measurement Arrays

The preceding sections describe how to query the formatted data array using the TRACE:DATA? query with the argument is the last array in the analyzer’s data processing chain, and is generally of most interest.

The analyzer also allows you to query other measurement arrays which are earlier in its data processing chain. Figure 6-2, below, shows the data processing chain.

CHlFDATA.

The formatted array

Raw Data

A.B.R... Correction

1-d

Ratio

Figure

6.2.

Numeric Data Flow Through the Network Analyzer

The first array is the Raw Data Array, which contains each of the separate

input components (A, B, R, measured. These arrays can be queried and set, but doing so is of limited use, since the data values contained in the arrays are uncorrected, and are not directly correlated to any meaningful reference, such as 0

Error

Coefficient

Arrays

Format

Markers

Limit Testing

B*,

R*, X, Y, AUX) immediately after they are

Offs.4

SCCll.5

Dota Trace

Memory Trace

dBm.

6-14

Trace Data Transfers

Accessing Other Measurement Arrays

The Error Coefficient Arrays contain default correction values or values created during a measurement calibration. These arrays can be queried and set, but care should be exercised in setting them since incorrect

measurements may result. If you wish to apply your own corrections in

addition to the analyzer’s current correction, the best technique is to use the

Corrected Memory array and the Data/Memory feature, explained below. The Corrected Data array contains the results of the currently selected

measurement (Transmission, Reflection, etc.) after error correction and averaging have been applied. The measurement data in these arrays is represented as complex number pairs. When measuring the transmission response of a through cable, the magnitude of the complex numbers will be very close to 1 .O. When measuring an open circuit, the magnitude of the complex numbers will be very close to 0.0. When measuring an

amplilier,

the

magnitude of the complex numbers will be greater than 1.0. The Corrected Memory array is filled with a copy of the Corrected Data array

when the Data --> Memory operation is performed. It can be used to apply a gain correction to the measured data. This is described in the following section.

The Formatted Data array contains the measurement data after it has been formatted using the format selected by the [FORMAT] menu. Querying the Formatted Data array is described in detail at the beginning of this chapter. You can also download data to this array, and the analyzer will display the

data using the current Scale and Reference values.

6-15

Applying Gain Correction Using the Memory Trace

The Corrected Memory array is Elled with a copy of the Corrected Data array when the Data --> Memory operation is performed. By setting the analyzer to perform Data/Memory trace math, you can apply your own correction factor to the measurement data trace by filling the Corrected Memory array with the appropriate complex numbers.

In general, you should use the analyzer’s calibration feature to correct for errors in your system. However, there may be cases where you wish to simulate the effect of adding a cable in series with your DUT, and observe how this imaginary cable will attenuate the measured response versus frequency. Or you may wish to apply an absolute offset to simulate the effect of adding or removing a pad from the measurement. These simulations are easily accomplished using the Corrected Memory array and the Data/Memory feature.

The Corrected Data and Memory arrays contain complex linear data, as opposed to logged data. When displaying the traces using Lin Mag format, the result of the Data divided by Memory operation to divide each point of the data trace by each point of the memory trace. When displaying data in Log Mag format, the result of Data/Memory will be equivalent to subtracting the Log Mag the Data trace.

value

of the Memory trace from that of

(Data/Mem)

will be

6-16

Trace Data Transfers

Applying Gain Correction Using the

Memory Trace

The following example BASIC code segment shows how to download a complex array from your program to the analyzer’s Memory trace. The program’s “Mem” array is initialized with the proper values such that when the analyzer computes Data divided by Memory, the desired increasing gain will be applied.

100

110 120 130 140 150 160 170 180

190 200 210 220

230 240 250 260 270 280 290 300 310 320

REAL

Mem(l:201,1:2)

ASSIGN

! Fill memory array (denominator in

QHp8711

TO 716

Data/Mem)

! with values that will result in an ! upward sloping gain factor vs. frequency. ! Used to compensate for cable loss vs. frequency ! Adds 0 dB of gain at start freq; 3

at stop freq

FOR Pt=l TO 201

Gain-factor-db=3.0*(Pt - 1)/200

0..3 dB

Power

Gain,factor~lin=lO~(Gain~factor,db/20) Mem(Pt,l)=l.O/Gain-factor-lin Mem(Pt,2)=0.0

! real

! imag

NEXT Pt

! Download to the memory trace OUTPUT OUTPUT

OHp87ll;"FORM:DATA

ASCII"

QHp8711;"TRACE:DATA CHlSMEM";

! Note the

'I;"

FOR Pt=l TO 201

FOR

I=1

TO 2

OUTPUT

QHp8711;",";Mem(Pt,I);

! Note the

";'I

NEXT I NEXT Pt OUTPUT OUTPUT

OHp8711;"" OHp8711,

*tVCALC1:MATH (IMPL/CHlSMEM)"

! Send

linefeed

Data/Mem

The example above downloads data to the corrected memory array. The data is sent by the program to the analyzer using ASCII encoding. The data is sent as ASCII characters, separated by commas. The analyzer accepts the comma separated list of numbers until it receives a

linefeed

to terminate the command. The program uses semicolons at the end of some OUTPUT statements to avoid sending a

linefeed

until all of the data has been sent. After the last number is sent, the program sends a linefeed, and the analyzer accepts the data.

Remember, for faster transfers, use binary data encoding instead of ASCII.

6-17

Performing Your Own Data Processing

After the analyzer has made a measurement, you can read the measurement trace and perform your own post-processing on it, and display the result on the screen. This is done using these steps:

1. Initiate a sweep

2. Wait for the sweep to

3. Read the measurement data into an array in your program

4. Perform your post-processing on the measurement data

5. Write (download) the post-processed data to the analyzer’s memory trace.

You may want to instruct the analyzer to display only the memory trace and not the data trace, so that only your post-processed data is seen.

Crush

6-18

Trace Data Transfers

Performing Your Own Data Processing

The program below demonstrates how to perform data post-processing. It takes the measurement data and reverses it, such that the low frequency data is displayed on the right end of the trace, and the high frequency data is displayed on the left.

100 110

120 130 140 150 160 170 180

190 200 210 220 230 235 240 250 260 270 280 290

! Display the measurement data backwards

REAL

Fmt(l:201)

ASSIGN

OHp8711

TO 716

OUTPUT OUTPUT OUTPUT

QHp871l;"FORM:DATA

QHp87ll;"ABOR;INIT:CONT OHp87ll;"DISP:WIND:TRACl

ASCII"

OFF;*WAI"

OFF;TRAC2

ON"

LOOP

! Take sweep

OUTPUT

QHp8711;"INITl;*WAI"

! Read the trace from the formatted data array

OUTPUT

ENTER

OHp871l;"TRACE:DATA?

QHp8711;Fmt(*)

CHlFDATA"

! Download the trace, backwards, ! to the formatted memory array

OUTPUT

QHp87ll;"TRACE:DATA CHIFMEM";

! Note the

FOR Pt=l TO 201

OUTPUT

OHp87ll;",";Fmt(202-Pt);

! Note the

NEXT Pt

OUTPUT

(QHp8711;""

! Send

linefeed

END LOOP

";'I 'I;"

This example program uses ASCII trace data transfers. Higher speed can be achieved using binary data transfers. If using

can be used for even greater performance. Refer to the

BASIC,

high-speed subroutines

IBASIC

Handbook for

details.

6-19

Downloading Trace Data Using Binary Encoding

Data traces can be downloaded to the analyzer using binary encoding. Using binary encoding is faster than using ASCII encoding. As mentioned

in Chapter 4, the binary encoded trace is transferred as a block; the block

containing a header and a data section. There are two different types of blocks that can be used: a definite length block, and an indefinite length block.

To send trace data using a definite length block, your program must calculate

the number of bytes in the data segment of the block, and create a block

header which tells the analyzer how many bytes are in the data segment. For example, if you are sending a trace with 201 data points and using

floating point numbers for each data point (“FORM:DATA block’s data segment will contain 1608 bytes (201 points * 8 bytes/point).

The header characters for a 1608 byte block are:

after the In this case, 4 digits follow, and those digits are “ block contains 1608 bytes.

For example :

When you send a definite length block to the analyzer, the analyzer will will read the data segment bytes, stopping when it receives the number specified in the block header.

To send trace data using an indefinite length block, your program simply sends a block header of the data segment, your program must terminate the data block by sending an EOI. The analyzer an EOI. To send an EOI using BASIC, you can use the statement:

“#“,

“4” tells how many following digits are used to specify the size.

TRAC

CHlFDATA,#41608<binary_data_starts_here>

“#O”,

followed by the data segment. After sending

will

read the data segment bytes, stopping when it receives

OUTPUT

QHp871l;END

“#41608”.

1608”,

REAL,64”),

The

meaning that the

lirst

64-bit

the

digit

6-20

Internal Measurement Arrays

The following sections describe the sequence of math operations and the resulting data arrays as the measurement information flows from the raw data arrays to the display. This information explains the measurement arrays accessible via

Figure 6-3 is a data processing flow diagram that represents the flow of numerical data. The data passes through several math operations, denoted in the figure by single-line boxes. Most of these operations can be selected and controlled with the front panel CONFIGURE block menus. The data is stored in arrays along the way, denoted by double-line boxes. These arrays are places in the flow path where data is accessible via HP-IB. While only a single flow path is shown, two identical paths are available, corresponding to measurement channels 1 and 2.

HP-B

Averaging

Format

Limit Testing

Figure 6-3. Numeric Data Flow Through the Network Analyzer

Offset

Scale

Data Trace Memory

Trace

6-21

Trace Data Transfers

Internal Measurement Arrays

Raw Data Arrays

These arrays are linear measurements of the inputs used in the selected measurement. Note that these numbers are complex pairs. These arrays are directly accessible via and CH Cl I23 RFWD.

HP-E3

and referenced as CH Cl

Table 6-4. Raw Data Arrays

I21

AFWD, CH Cl

I21

BFWD

Selected Measurement

Transmission IB/RJ Reflection A

lA.Ffl

Power 18”)

Conversion

R”

AM Delay (Y/XI X

Y Y/R” Y/X,

loss IB”/R*l

NOTE

Raw data far AUX INPUT is not available via HP-IB. Use the corrected data array to access AUX

INPUT data.

B -

CH[l

21BFWD,

A =

CH[l

21AFWD.

A -

CH[l

21AFWD

B -

CH[l

21BFWD

R -

CH[l

21RFWD

B’

CH[:

lZ]BFWD

= CH[I12]BFWD,

B” R”

- CH[li21RFWD

Y -

CH[ltZ]BFWD,X- CHCll21RFWD

X =

CHC1121RFWD

Y -

CH[ltZ]BFWD

Y -

CH[1121BFWD,

Y =

CH[1121BFWD,X =

Raw Arrays

R R

R”

I21RFWD

CHCl

121RFWD

CH[l

= CH[llZ]RFWD

- CHCll21RFWD

CHkl21RFWD

6-22

Ratio Calculations

Trace Data Transfers

Internal Measurement Arrays

These are performed if the selected measurement is a ratio (e.g. A/R or This is simply a complex divide operation. If the selected measurement is absolute (e.g. A or B), no operation is performed.

B/R).

Error Correction

Error correction is performed next if correction is turned on. Error correction removes repeatable systematic errors (stored in the error coefficient arrays) from the raw arrays. The operations performed depend on the selected measurement type.

Error Coefficient Arrays

The error coefficient arrays are either default values or are created during a measurement calibration. These are used whenever correction is on. They contain complex number pairs, and are accessible via HP-IB and are referenced as CH [l

CHClt21SCORR4.

I21 SCORRl,

CH [l

I21 SCORR2,

CH Cl

I21 SCORR3

and

6-23

Trace Data Transfers

Internal Measurement Arrays

Table 6-5. Error Coefficient Arrays

Selected Measurement

Transmission fB/R) Response Transmission

[B/RI

Response & Isolation

CH [I f 21

CH[ll2]SCORRI

CH [l

Transmission (B/RI Enhanced Response

CH [l CH [l CH CH

Reflection

[AIR]

CH CH

CH[l

Broadband Internal

NOTE

These arrays do not apply to Broadband External measurements.

CH[ll2]SCORRl

Error Coefficient Arrays

SCORRI

f 21

SCORRZ

I21SCORRl

f 21

SCORR2

I 21

SCORR3

I 21

SCORR4

I 21

SCORRI

[I 121

SCORR2

I21

SCORR3

Tracking

Isolation Term

Directivity

Source Match

Reflection Tracking

Transmission Tracking

Diractivity

Source Match

Tracking

A” Response

6-24

Agilent 8711C Programming Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

HP-IB Programming

Introduction to HP-IB Programming

Bus Structure

Data Bus

Handshake Lines

Sending Commands

HP-IB Requirements

Interface Capabilities

Programming Fundamentals

Controller Capabilities

Response to Bus Management Commands

Message Exchange

Synchronizing the Analyzer and a Controller

Synchronizing the Analyzer and a Controller

Overlapped Commands

The NPO Flag

Usage of *WA1 and *OPC?

Passing Control

Passing Control

Data Types and Encoding

Data Types and Encoding

Data Types

Numeric Data

Character Data

String Data

Expression Data

Block Data

Data Encoding for Large Data Transfers

ASCII Encoding

Binary Encoding

Byte Swapping

Using Status Registers

Using Status Registers

General Status Register Model

Condition Register

Transition Registers

Event Register

Enable Register

How to Use Registers

The Service Request Process

The Analyzer’s Status Register Sets

Status Byte

Device Status Register Set

Limit Fail Register Set

Questionable Status Register Set

Standard Event Status Register Set

Measuring Status Register Set

Averaging Status Register Set

Operational Status Register Set

STATus:PRESet Settings

Analyzer Register Set Summary

Trace Data Transfers

Trace Data Transfers

Querying the Measurement Trace Using BASIC

@Smith Chart and Polar Formats

Querying the Measurement Trace Using SICL

Using Binary Data Encoding

Trace Data Transfer Sizes

CALC:DATA? versus TRACE:DATA?

Querying Single Data Points Using Markers

Accessing Other Measurement Arrays

Applying Gain Correction Using the Memory Trace

Performing Your Own Data Processing

Downloading Trace Data Using Binary Encoding

Internal Measurement Arrays

Raw Data Arrays

Ratio Calculations

Error Correction

Error Coefficient Arrays

Usage of WA1 and OPC?