Agilent Technologies 3458A User Manual

Chapter 6 Command Reference 187
ISCALE?
control The control parameter choices are:
Power-on control = OFF.
Default control = ON.
Remarks • Turning the input buffer OFF causes a minor degradation in speed performance,
but is useful for synchronizing bus activity. With the input buffer OFF, the
multimeter accepts only one command at a time and does not release the bus
until it has finished executing that command. This ensures that subsequent
commands sent to other bus devices cannot be executed until the multimeter has
finished executing its command(s).
• Turning the input buffer ON causes the multimeter to buffer (store) incoming
messages and release the GPIB bus as soon as message transmission is complete.
This allows the controller to communicate with other bus devices while the
multimeter executes its command(s). However, synchronization with other bus
devices may be lost if they execute their instructions before the multimeter
finishes its instructions. In this case, the ready bit in the status register may be
monitored (using a serial poll) to determine when the multimeter is finished.
• A series of commands longer than 255 characters fills the input buffer and causes
the multimeter to halt bus activity while it executes the first commands received.
The remainder of the message is input when room becomes available in the
buffer.
• Query Command. The INBUF? query command returns the present input
buffer mode. Refer to "Query Commands" near the front of this chapter for more
information.
Example The following program enables the input buffer prior to running all of the
autocalibration routines. This prevents the bus from being held during the autocal
which takes over 11 minutes to complete.
10 OUTPUT 722;"INBUF ON" !ENABLE INPUT BUFFER
20 OUTPUT 722;"ACAL ALL" !AUTOCAL (TAKES >ll MINUTES)
30 END
ISCALE?
Integer Scale Query. Returns the scale factor for readings output in the SINT or
DINT formats.
control
Parameter
Numeric
Query
Equiv. Description
OFF 0 Disables the input buffer; commands are accepted
only when the multimeter is not busy
ON 1 Enables the input buffer; commands are stored,
releasing the bus immediately

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