Agilent Technologies 3458A User Manual

LFILTER
190 Chapter 6 Command Reference
circuitry only. This does not affect the coupling of the signal being measured.
Power-on coupling = AC.
Default coupling = AC.
Remarks • Level triggering can be used for DC voltage, direct-sampling, and sub-sampling.
(The LEVEL command also affects the zero crossing threshold and the input
signal coupling for frequency and period measurements.) For DC voltage and
direct-sampling, level triggering can be used as the trigger event (TRIG LEVEL
command) or the sample event (NRDGS n, LEVEL command). For
sub-sampling, level triggering can be used for the sync source event only (SSRC
LEVEL command).
• Because of hysteresis, the actual level triggering point is the specified
percentage ±4% of the measurement range.
• Autozero should be disabled when using level triggering (AZERO OFF
command) for DC voltage measurements. (Autozero doesn't apply to direct- or
sub-sampling.)
• Query Command. The LEVEL? query command returns two responses
separated by a comma. The first response is the currently specified percentage.
The second response is the present coupling mode. Refer to "Query Commands"
near the front of this chapter for more information.
• Related Commands: DCV, DSAC, DSDC, LFILTER, NRDGS, SETACV,
SYNC, SLOPE, SSAC, SSDC, SSRC, TRIG
Example 10 OUTPUT 722;"TARM HOLD" !SUSPENDS TRIGGERING
20 OUTPUT 722;"PRESET DIG" !FAST DCV MEASUREMENTS, 10V RANGE
30 OUTPUT 722;"TRIG LEVEL" !SELECT LEVEL TRIGGER EVENT
40 OUTPUT 722;"SLOPE POS" !TRIGGER ON POSITIVE SLOPE OF SIGNAL
50 OUTPUT 722;"LEVEL 50,AC" !TRIGGER AT 50% OF 10V RANGE (5V) AC-COUPLED
60 END
LFILTER
Level Filter. Enables or disables the level filter function. When enabled, the level
filter function connects a single pole low-pass filter circuit to the input of the
level-detection circuitry. The low-pass filter has a 3-dB point of 75 kHz and
prevents high frequency components from causing false triggers.
coupling
Parameter
Numeric
Query
Equiv. Description
DC 1 Selects DC-coupled input to level-detection
circuitry
AC 2 Selects AC-coupled input to level-detection
circuitry

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