Agilent Technologies 3458A User Manual

Chapter 6 Command Reference 237
SSAC, SSDC
SSAC, SSDC
Sub-Sampling. Configures the multimeter for sub-sampled voltage
measurements (digitizing). The SSAC function measures only the AC component
of the input waveform. The SSDC function measures the combined AC and DC
components of the waveform. Otherwise, the two functions are identical. The
input signal must be periodic (repetitive) for sub-sampled measurements.
Sub-sampled measurements use the track/hold circuit (2 nanoseconds aperture)
and a wide bandwidth input. path (12 MHz bandwidth).
Syntax SSAC [max._input] [,% resolution]
SSDC [max._input] [,%_resolution]
max._input
Selects the measurement range (you cannot use autorange for sub-sampled
measurements). To select a range, you specify max._input as the input signal's
expected peak amplitude. The multimeter then selects the correct range. The
following table shows the max._input parameters and the ranges they select.
Power-on max._ input = not applicable.
Default max._input = 10V.
% resolution
Is ignored by the multimeter when used with the SSAC or SSDC command. This
parameter is allowed in the command syntax to be consistent with the other
function commands (FUNC, ACI, DCV, etc.).
Remarks • Autozero and autorange do not function for sub-sampled measurements.
Executing the SSAC or SSDC command suspends autozero and autorange
operation.
• As with direct-sampling, you can specify a level triggering voltage up to 500%
of the range. The required SINT format, however, cannot handle samples greater
then 120% of range.
• If reading memory is disabled when you execute the SSAC or SSDC command,
the multimeter automatically sets the output format to SINT (the memory format
max._input
Parameter
Selects
Range
Full
Scale
0 to .012 10mV 12mv
>.012 to .120 100mV 120mV
>.120 to 1.2 1V 1.2V
>1.2 to 12 10V 12V
>12 to 120 100V 120V
>120 to 1E3 1000V 1050V

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