Agilent Technologies 3458A User Manual

322 Appendix D Optimizing Throughout and Reading Rate
the speed of testing. For example, in many systems accuracy can be traded for
speed; or flexibility in timing the measurement can lead to real increases in the
rate of rms AC measurements with good accuracy. The set of trade-offs one may
make with the 3458A Multimeter is covered in detail in this Product Note.
Maximizing the Testing Speed
Program Memory The speed of the testing process can also be maximized by tailoring the
communication path between the 3458A and the computer. The dmm is generally
the fastest instrument in the system; hence to perform a series of measurements,
the computer may be compelled to take more time with other instruments. Several
features of the 3458A Multimeter allow the allocation of measurement tasks to
be split optimally between the computer and the dmm. Its unique, non-volatile
Program Memory allows sequences of measurement to be performed dynamically
using external events such as external, auxiliary, or GPIB
1
triggers to step through
the measurement sequence. In addition, using Program Memory, complete
measurement sequences can be programmed and initiated from the front panel for
standalone operation without a controller.
State Storage State Storage permits a static instrument state to be totally defined and recalled
from memory with a simple program command. In addition, the 3458A transfers
high-speed measurement data over GPIB or into and out its standard 10,000 (or
optional 75,000) Reading Memory at 100,000 readings per second.
Reading Analysis Additional flexibility is provided by the 3458A's capability to perform data
analysis internally to speed throughput and still give you the data you need for
statistica1 quality control or for simple limit checking. Program Memory can
perform the pass/fail math function and alert the computer to out-of-limits
measurements with an interrupt flag. Alternatively, the many available math
functions may be used to post-process the data acquired in memory, without loss
of the maximum reading rate. These include statistical functions (mean, standard
deviation, maximum, minimum, number of readings), dB and dBm, thermistor
linearization, RTD linearization, scale, filter functions, and others. The choice of
whether to perform data analysis in the computer or in the dmm depends on the
testing task and the convenience offered to the user by having these analysis
functions available with a simple programming command.
Task Grouping and
Sequence
Further gains in test throughput can be obtained by tailoring the measurement
sequence to group similar measurements together, thus minimizing the number
of instrument configuration changes between measurements. Custom programs
written without the aid of automatic program generators can be so structured.
Program generators are usually optimized for ease of programming and offer a
simplistic approach to the testing task that lets you choose limits for each group
of tests but do not necessarily group the tests for the fastest throughput. Functional
test management software like the FTM300 allows the tests to be customized for
1. GPIB is an implementation of the IEEE Standard 488 and the identical ANSI Standard MC1.1 "Digital
interface for programmable instrumentation "

Agilent Technologies 3458A Specifications

General

Model	3458A
Manufacturer	Agilent Technologies
Category	Multimeter
Digits	8.5
Sampling Rate	100, 000 readings/second
Interface	GPIB

Summary

Safety Symbols and Warnings

General Safety Precautions (WARNINGS)

Outlines essential safety precautions for operating, servicing, and repairing the product to prevent injury or damage.

Chapter 2 Getting Started

Operating from the Front Panel

Covers using front panel keys, making measurements, changing functions, and controlling display settings.

Operating from Remote

Explains how to control the multimeter remotely via GPIB, including address management and command sending.

Chapter 3 Configuring for Measurements

General Configuration

Configuring for DC or Resistance Measurements

Details how to configure the multimeter for DC voltage, DC current, and 2-wire or 4-wire resistance measurements.

Configuring for AC Measurements

Explains how to configure the multimeter for AC voltage, AC current, frequency, or period measurements.

Chapter 4 Making Measurements

Triggering Measurements

Explains the three-event triggering hierarchy (arm, trigger, sample) and various event choices.

Using Reading Memory

Sending Readings Across the Bus

Increasing the Reading Rate

Discusses the multimeter's high-speed mode and factors affecting reading rate and transfer speed.

Math Operations

Explains real-time and post-process math operations, enabling/disabling them, and math registers.

Chapter 5 Digitizing

Digitizing Methods

Details DCV, Direct-Sampling, and Sub-sampling methods, summarizing their characteristics and signal paths.

The Sampling Rate

Level Triggering

Describes how to specify voltage and slope for sampling initiation, with examples for DCV and direct-sampling.

DCV Digitizing

Direct-Sampling

Explains direct-sampling using track-and-hold, its bandwidth, and specifying ranges via max._input parameter.

Sub-Sampling

Covers sub-sampling fundamentals, advantages, and how to specify effective interval and number of samples.

Chapter 6 Command Reference

ACAL

Instructs the multimeter to perform self-calibrations (ALL, DCV, AC, OHMS) and discusses autocalibration security.

NRDGS

OFORMAT

PRESET

Configures the multimeter to one of three predefined states: NORM, FAST, or DIG for different operation modes.

SUB

Stores a series of commands as a subprogram, assigning a name for later execution.

TARM

Defines the trigger arm event to enable the trigger event and can be used for multiple measurement cycles.

TEST

Causes the multimeter to perform a series of internal self-tests to check hardware and software integrity.

TRIG

Specifies the trigger event that initiates a measurement, working with TARM and NRDGS.

Chapter 7 BASIC Language for the 3458A

BASIC Language Commands

Subprograms

Explains how to store, execute, and manage BASIC language subprograms for system control and automation.

Appendix B GPIB Commands

TRIGGER (GET)

Appendix C Procedure to Lock Out Front/Rear Terminals and Guard Terminal Switches

Procedure

Outlines the steps for installing the switch lockout kit, including covers and pushrod removal.

Appendix D Optimizing Throughout and Reading Rate

Maximizing the Testing Speed

Covers strategies like tailoring communication paths, program memory, and state storage for optimal testing speed.

DC Volts, DC Current and Resistance

Explains the measurement paths (DCV, track-and-hold) and trade-offs for DC measurements.

AC Volts and AC Current

Details the three ACV measurement techniques (Analog, Synchronous, Random) and their trade-offs.

Frequency and Period

Optimizing the Testing Process Through Task Allocation

Discusses allocating tasks between the DMM and computer using math functions, memory, and program structure.

Math Operations

State Storage and Program Memory

A Benchmark

Appendix E High Resolution Digitizing With the 3458A

Speed with Resolution

Details the multimeter's flexibility in speed and resolution for audio frequency bandwidth.

Digitizing Analog Signals

Avoiding Aliasing

Provides methods to avoid signal distortion caused by aliasing, ensuring accurate waveform representation.

Choice of Two Measurement Paths

Describes the standard DCV path and the track-and-hold path for digitizing and sampling.

Capturing the Data

High Speed Data Transfers

Errors in Measurements