HP 54620A Manual

Programmer’s Guide
Publication Number 54620-97012
October 1995 (pdf version Dec 1998)
For Safetyinformation, Warranties,and Regulatory information,
seethepagesbehind the Index.
©Copyright Hewlett-Packard Company1994, 1995
All RightsReserved
HP 54620A/C Logic Analyzer

Programming the Logic Analyzer
When you attach an interface module to the rear of the HP 54620A or
HP 54620C (color) Logic Analyzer, the analyzer becomes
programmable. That is, you can hook a controller (such as a PC or
workstation) to the analyzer, and write programs on that controller to
automate analyzer setup and data capture. Both HP-IB (also known as
GP-IB, IEEE-488) and RS-232-C interfaces are available.
The following figure shows the basic structure of every program you
will write for the analyzer.
Initialize
To ensure consistent, repeatable performance, you need to start the
program, controller, and analyzer in a known state. Without correct
initialization, your program may run correctly in one instance and not
in another. This might be due to changes made in configuration by
previous program runs or from the front panel of the logic analyzer.
•Program initialization defines and initializes variables, allocates
memory, or tests system configuration.
•Controller initialization ensures that the interface to the analyzer
(either HP-IB or RS-232) is properly setup and ready for data
transfer.
•Analyzer initialization sets the channel configuration and labels,
threshold voltages, trigger specification and mode, timebase, and
acquisition type.
2

Capture
Once you initialize the analyzer, you can begin capturing data for
analysis. Remember that while the analyzer is responding to
commands from the controller, it is not performing acquisitions. Also,
when you change the analyzer configuration, any data already
captured is most likely invalid.
To collect data, you use the :DIGitize command. This command clears
the waveform buffers and starts the acquisition process. Acquisition
continues until acquisition memory is full, then stops. The acquired
data is displayed by the analyzer, and the captured data can be
measured, stored in trace memory in the analyzer, or transferred to
the controller for further analysis. Any additional commands sent
while :DIGitize is working are buffered until :DIGitize is complete.
You could also start the analyzer running, then use a wait loop in your
program to ensure that the analyzer has completed at least one
acquisition before you make a measurement. HP does not recommend
this because the needed length of the wait loop may vary, causing
your program to fail. :DIGitize, on the other hand, ensures that data
capture is complete. Also, :DIGitize, when complete, stops the
acquisition process so that all measurements are on displayed data,
not on a constantly changing data set.
Analyze
After the analyzer has completed an acquisition, you can find out
more about the data, either by using the analyzer measurements or by
transferring the data to the controller for manipulation by your
program. Built-in measurements include frequency, duty cycle,
period, positive and negative pulse width, channel-to-channel delay,
and setup and hold time.
Using the :WAVeform commands, you can transfer the data to your
controller. You may want to display the data, compare it to a known
good measurement, or simply check logic patterns at various time
intervals in the acquisition.
3

In This Book
The HP 54620A/C Programmer’s Guideis your introductionto
programmingtheHP 54620A or HP54620C (color)Logic Analyzer using an
instrumentcontroller.This book, with the HP 54620A/C Programmer’s
Reference,provides a comprehensive description ofthe analyzer’s
programmatic interface.The Programmer’sReferenceis suppliedas a
MicrosoftWindows Helpfile ona 3.5" diskette.
To program the HP54620A/C, you need an interface module, such as the
HP54650A,54651A, or54652B.Youalsoneedaninstrumentcontrollerthat
supportseither the IEEE-488orRS-232-C interface standards,and a
programminglanguage capable of communicatingwith these interfaces.
This bookcontains the followinginformation:
Chapter 1,“Introduction toProgramming,” givesa general overview oflogic
analyzer programming.
Chapter 2,“Programming Getting Started,” shows a simpleprogram, explains
its operation, and discusses considerations for data types.
Chapter 3,“Programming over HP-IB,” discusses the generalconsiderations
for programming the instrumentover an HP-IB interface.
Chapter 4,“Programming over RS-232-C,” discussesthegeneral
considerationsfor programming the instrumentover an RS-232-C interface.
Chapter 5,“Programming and Documentation Conventions,” describes the
conventions used in representingthesyntax ofcommands throughout this
book and the HP 54620A/CProgrammer’sReference,and gives an overview
of the analyzer command set.
Chapter 6,“Status Reporting,” discusses the analyzer statusregisters and
how touse themin your programs.
Chapter7,“Installingand Using the Programmer’s Reference,”tells howto
install the HP 54620A/CProgrammer’sReferenceonline helpfilein
MicrosoftWindows, and explains help file navigation.
Chapter 8,“Programmer’s QuickReference,” lists all the commands and
queriesavailablefor programming the logic analyzer.
For information on analyzer operation,seetheHP 54620A/C User’s Guide.
For information oninterface configuration,seethedocumentation for the
analyzer interface module and theinterface card used in your controller (for
example, the HP82341Ainterface for IBM PC-compatible computers).
4

ProgrammingGettingStarted
2
Programmingover HP-IB
3
Programmingover RS-232-C
4
Programmingand
DocumentationConventions
5
Status Reporting
6
Installing and Using the
Programmer’s Reference
7
Programmer’s Quick Reference
8
Introduction to Programming
1
Index
5

6

Contents
1 Introduction to Programming
Talking to the instrument 11
Program message syntax 12
Combining commands from the same subsystem 15
Duplicate mnemonics 15
Query command 16
Program header options 17
Program data syntax rules 18
Program message terminator 20
Selecting multiple subsystems 20
2 Programming Getting Started
Initialization 23
Autoscale 24
Setting up the instrument 24
Example program 25
Program overview 27
Using the :DIGitize command 28
Receiving information from the instrument 30
String variables 31
Numeric variables 32
Definite-length block response data 33
Multiple queries 34
Instrument status 34
3 Programming over HP-IB
Interface capabilities 37
Addressing 37
Communicating over the bus 38
Lockout 39
Bus commands 39
4 Programming over RS-232-C
Interface operation 43
Cables 43
7

Configuring the interface 46
Interface capabilities 46
Lockout Command 47
5 Programming and Documentation Conventions
Command Set Organization 51
The command tree 52
Truncation rules 56
Infinity representation 57
Sequential and overlapped commands 57
Response generation 57
Notation conventions and definitions 58
Program Examples 59
6 Status Reporting
Serial poll 66
7 Installing and Using the Programmer’s Reference
To install the help file under Microsoft Windows 71
To use the help text and example program files 72
To get updated help and program files via the Internet 73
To start the help file 74
To navigate through the help file 75
8 Programmer’s Quick Reference
Introduction 78
Conventions 79
Suffix multipliers 79
Commands and Queries 80
Index 89
Contents
8

1
Introduction to Programming

Introduction to Programming
Chapters 1 and 2 introduce the basics for remote programming of a
logic analyzer. The programming instructions in this manual conform
to the IEEE 488.2 Standard Digital Interface for Programmable
Instrumentation. The programming instructions provide the means of
remote control.
To program the HP 54620A Logic Analyzer or HP 54620C (color)
Logic Analyzer, you must add either an HP-IB (for example,
HP 54650A) or RS-232-C (for example, HP 54651A or HP 54652B)
interface to the rear panel.
You can perform the following basic operations with a controller and a
logic analyzer:
•Set up the instrument.
•Make measurements.
•Get data (waveform, measurements, configuration) from the logic
analyzer.
•Send information (pixel image, configurations) to the logic
analyzer.
Other tasks are accomplished by combining these basic functions.
Languages for Program Examples
The programming examplesfor individual commandsin this manual are written
in HP BASIC or C.
10

Talking to the instrument
Computers acting as controllers communicate with the instrument by
sending and receiving messages over a remote interface. Instructions for
programming normally appear as ASCII character strings embedded inside
the output statements of a “host” language available on your controller. The
input statements of the host language are used to read in responses from the
logic analyzer.
For example, HP BASIC uses the OUTPUT statement for sending commands
and queries. After a query is sent, the response is usually read in using the
ENTER statement.
Messages are placed on the bus using an output command and passing the
device address, program message, and terminator. Passing the device address
ensures that the program message is sent to the correct interface and
instrument.
The following HP BASIC statement sends a command which sets the
threshold voltage for channels 0 through 7 to TTL:
OUTPUT < device address > ;
":LCHANNEL:THRESHOLD LCHAN0_7,TTL"<terminator>
The < device address > represents the address of the device being
programmed. Each of the other parts of the above statement are explained in
the “Program Message Syntax” which follows.
Introduction to Programming
Talking to the instrument
11

Program message syntax
To program the instrument remotely, you must understand the command
format and structure expected by the instrument. The IEEE 488.2 syntax
rules govern how individual elements such as headers, separators, program
data, and terminators may be grouped together to form complete
instructions. Syntax definitions are also given to show how query responses
are formatted. Figure 1 shows the main syntactical parts of a typical program
statement.
Program Message Syntax
Output Command
The output command is entirely dependent on the programming language.
Throughout this manual, HP BASIC is used in most of the individual
command exampless. If you are using other languages, you must find the
equivalents of HP BASIC commands like OUTPUT, ENTER, and CLEAR to
convert the examples. For example, the example progam in chapter 2 is
written in C, and uses the library function IOOUTPUTS to send a command.
The instructions listed in this manual are always enclosed in quotation marks
in the example programs.
Device Address
The location where the device address must be specified also depends on the
programming language you are using. In some languages, this may be
specified outside the output command. In HP BASIC, this is always specified
after the keyword OUTPUT. The examples in this manual assume the logic
analyzer is at device address 707. When writing programs, the address varies
according to how the bus is configured.
Figure 1
Introduction to Programming
Program messagesyntax
12

Instructions
Each instruction (for both commands and queries) normally appears as a
string embedded in a statement of your host language, such as BASIC, Pascal,
or C. The only time a parameter is not meant to be expressed as a string is
when the instruction’s syntax definition specifies <block data>. There are
only a few instructions that use block data. See the :WAVeform:DATA? query
for an example of a command that uses block data.
Instructions are composed of two main parts:
•The header, which specifies the command or query to be sent.
•The program data, which provides additional information needed to clarify
the meaning of the instruction.
Instruction Header
The instruction header represents the operation to be performed by the
instrument, and is one or more mnemonics separated by colons (:). The
command tree in chapter 5 illustrates how all the mnemonics can be joined
together to form a complete header (see chapter 5, “Programming and
Documentation Conventions”).
The example in figure 1 is a command. Queries are indicated by adding a
question mark (?) to the end of the header. Many instructions can be used as
either commands or queries, depending on whether or not you have included
the question mark. The command and query forms of an instruction usually
have different program data. Many queries do not use any program data.
White Space (Separator)
White space is used to separate the instruction header from the program
data. If the instruction does not require any program data parameters, you do
not need to include any white space. In this manual, white space is defined as
one or more spaces. ASCII defines a space to be character 32 (in decimal).
Program Data
Program data are used to clarify the meaning of the command or query. They
provide necessary information, such as whether a function should be on or
off, or which waveform is to be displayed. Each instruction’s syntax definition
shows the program data, as well as the values they accept. The “Program
Data Syntax Rules” topic in this chapter describes all of the general rules
about acceptable values.
Introduction to Programming
Program message syntax
13

When there are more than one data parameter, they are separated by
commas (,). Spaces can be added around the commas to improve readability.
Header Types
There are three types of headers:
•Simple command headers
•Compound command headers
•Common command headers
Simple command header Simple command headers contain a single
mnemonic. :AUToscale and :DIGitize are examples of simple command
headers typically used in this instrument. The syntax is:
<program mnemonic><terminator>
Simple command headers must occur at the beginning of a program message;
if not, they must be preceded by a colon.
When program data must be included with the simple command header (for
example, :BLANk LCHan0), white space is added to separate the data from
the header. The syntax is:
<program mnemonic><separator><program data><terminator>
Compound command header Compound command headers are a
combination of two program mnemonics. The first mnemonic selects the
subsystem, and the second mnemonic selects the function within that
subsystem. The mnemonics within the compound message are separated
by colons. For example:
To execute a single function within a subsystem:
:<subsystem>:<function><separator><program data><terminator>
(For example :DISPlay:TEXT BLANk)
Common command header Common command headers control IEEE
488.2 functions within the instrument (such as clear status). Their
syntax is:
*<command header><terminator>
No space or separator is allowed between the asterisk (*) and the command
header. *CLS is an example of a common command header.
Introduction to Programming
Program messagesyntax
14

Combining commands from the same subsystem
To execute more than one function within the same subsystem a semi-colon
(;) is used to separate the functions:
:<subsystem>:<function><separator><data>;
<function><separator><data><terminator>
(For example :TIMebase:REFerence LEFT;VERNier ON)
Duplicate mnemonics
Identical function mnemonics can be used for more than one subsystem. For
example, the function mnemonic DELAY may be used to set the trigger delay
or measure channel-to-channel delay:
:TIMEBASE:DELAY 30 US
sets the trigger delay to 30 µs.
:MEASURE:DELAY
measures the delay betwen predefined start and end channels (see
:MEASure:DEFine:DELay).
:TIMebase and :MEASure are subsystem selectors and determine which
meaning of DELAY is used.
Introduction to Programming
Combining commands from the same subsystem
15

Query command
Command headers immediately followed by a question mark (?) are queries.
After receiving a query, the instrument interrogates the requested function
and places the answer in its output queue. The answer remains in the output
queue until it is read or another command is issued. When read, the answer is
transmitted across the bus to the designated listener (typically a controller).
For example, the query :TIMebase:RANGE? places the current time base
setting in the output queue. In HP BASIC, the controller input statement:
ENTER < device address > ;Range
passes the value across the bus to the controller and places it in the variable
Range.
Query commands are used to find out how the instrument is currently
configured. They are also used to get results of measurements made by the
instrument. For example, the command :MEASure:PERiod? instructs the
instrument to measure the period of the current measurement source
channel and places the result in the output queue.
The output queue must be read before the next program message is sent. For
example, when you send the query :MEASure:PERiod? you must follow that
query with an input statement. In HP BASIC, this is usually done with an
ENTER statement immediately followed by a variable name. This statement
reads the result of the query and places the result in a specified variable.
Read the QueryResult First
Sending another command orquery before readingthe result of a query causes
the output bufferto be cleared and the current response to be lost.This also
generates a query interruptederror in the error queue.
Introduction to Programming
Query command
16

Program header options
Program headers can be sent using any combination of uppercase or
lowercase ASCII characters. Instrument responses, however, are always
returned in uppercase.
Program command and query headers may be sent in either long form
(complete spelling), short form (abbreviated spelling), or any combination of
long form and short form. For example:
TIMEBASE:DELAY 1US - long form
TIM:DEL 1US - short form
Programs written in long form are easy to read and are almost
self-documenting. The short form syntax conserves the amount of controller
memory needed for program storage and reduces the amount of I/O activity.
CommandSyntax Programming Rules
The rulesfor the short form syntax are described inchapter5, “Programming
and Documentation Conventions.”
Introduction to Programming
Program header options
17

Program data syntax rules
Program data conveys a variety of types of parameter information related to
the command header. At least one space must separate the command header
or query header from the program data.
<program mnemonic><separator><data><terminator>
When a program mnemonic or query has multiple program data, a comma
separates sequential program data.
<program mnemonic><separator><data>,<data><terminator>
For example, :DISPlay:PIXel 10,12,2 has three program data: 10, 12, and 2.
There are two main types of program data used in commands: character and
numeric program data.
Character Program Data
Character program data conveys parameter information as alpha or
alphanumeric strings. For example, the :TIMebase:MODE command can be
set to normal or delayed. The character program data in this case may be
NORMal or DELayed. The command :TIMebase:MODE DELayed sets the
time base mode to delayed.
The available mnemonics for character program data are always included
with the instruction’s syntax definition. When sending commands, either the
long form or short form (if one exists) may be used. Uppercase and
lowercase letters may be mixed freely. When receiving query responses,
uppercase letters are used exclusively.
Numeric Program Data
Some command headers require program data to be expressed numerically.
For example, :TIMebase:RANGe requires the desired full-scale range to be
expressed numerically.
For numeric program data, you have the option of using exponential notation
or using suffix multipliers to indicate the numeric value. The following
numbers are all equal:
28 = 0.28E2 = 280e-1 = 28000m = 0.028K = 28e-3K
When a syntax definition specifies that a number is an integer, it means that
the number should be whole. Any fractional part would be ignored,
truncating the number. Numeric data parameters that accept fractional
values are called real numbers.
Introduction to Programming
Program data syntax rules
18

All numbers are expected to be strings of ASCII characters. Thus, when
sending the number 9, you would send a byte representing the ASCII code for
the character “9” (which is 57). A three-digit number like 102 would take up
three bytes (ASCII codes 49, 48, and 50). This is taken care of automatically
when you include the entire instruction in a string.
Embedded Strings
Embedded strings contain groups of alphanumeric characters which are
treated as a unit of data by the logic analyzer. For example, this line of text
written to the advisory line of the instrument with the :SYSTem:DSP
command is an embedded string:
:SYSTEM:DSP"This is a message."
Embedded strings may be delimited with either single (’) or double (")
quotation marks. These strings are case-sensitive, and spaces act as legal
characters—just like any other character.
Introduction to Programming
Program data syntax rules
19

Program message terminator
The program instructions within a data message are executed after the
program message terminator is received. The terminator may be either an NL
(New Line) character, an EOI (End-Or-Identify) asserted in the HP-IB
interface, or a combination of the two. Asserting the EOI sets the EOI control
line low on the last byte of the data message. The NL character is an ASCII
linefeed (decimal 10).
New Line Terminator Functions
The NL (New Line) terminator hasthe same function as an EOS (End Of String)
and EOT(End Of Text) terminator.
Selecting multiple subsystems
You can send multiple program commands and program queries for different
subsystems on the same line by separating each command with a semicolon.
The colon following the semicolon enables you to enter a new subsystem. For
example:
<program mnemonic><data>;
:<program mnemonic><data><terminator>
:TRIGGER:MODE NORMAL;:TIMEBASE:RANGE 1
Combining Compound and SimpleCommands
Multiple commands may be any combination of compound andsimple
commands.
Introduction to Programming
Program messageterminator
20