Keithley 6430 User Manual

7-4 Relative and Math
Math operations
Math functions
The SourceMeter has built-in math functions to calculate the following:
• Power
• Offset Compensated Ω
• Varistor Alpha
• Voltage Coefficient
• Percent Deviation
The Power and Percent Deviation math functions use a single voltage and/or current mea-
surement to perform the calculation. The Offset-Compensated Ω, Varistor Alpha, and Voltage
Coefficient math functions require 2-point measurements to perform a calculation.
Power
This math function calculates power using the measured voltage and measured current val-
ues as follows:
Power = V × I
where: V = measured voltage
I = measured current
Offset-compensated Ω
The presence of thermal EMFs (V
EMF
) can adversely affect low-resistance measurement
accuracy. To overcome these unwanted OFFset voltages use the Offset Compensated Ω mea-
surement method. In general, this method measures resistance (V/I) at a specific I-Source level
and then subtracts a resistance measurement made with the I-Source set to a different level
(typically zero).
NOTE Offset-compensated Ω is also available from the CONFIG OHMS menu structure.
Using Offset-Compensated Ω from this menu automatically selects zero as one of the
source values. For details, see Section 4, “Offset-compensated ohms.”
This two-point measurement method is mathematically expressed as:
Offset-Compensated Ω = ∆V / ∆I where ∆V = V2 – V1 and ∆I = I2 – I1.
• V1 is the voltage measurement with the I-Source set to a specific level.
• V2 is the voltage measurement with the I-Source set to a different level (typically zero).
• I1 is the current measurement with the I-Source set to a specific level.
• I2 is the current measurement with the I-Source set to a different level (typically zero).
You will be prompted to enter the two I-Source values. See Front panel math operations.

Keithley 6430 Specifications

General

Type	Sub-Femtoamp Remote SourceMeter
Compliance Voltage	200 V
Maximum Output Voltage	200 V
Maximum Output Current	100 mA
Compliance Limit	Programmable
Interface	GPIB, RS-232
Input Impedance	>10^14 Ω

Summary

Safety Precautions

3 Basic Source-Measure Operation

Basic Source-Measure Procedure

Details setup for source-measure operations: function, values, limits, and output control.

5 Source-Measure Concepts

Compliance limit

Discusses compliance limits, values, and determination.

Operating boundaries

Covers voltage/current boundaries for source, sink, I-source, V-source, and source-measure modes.

6 Range, Digits, Speed, and Filters

Range and digits

Discusses available ranges, limits, manual/autoranging, and display resolution.

Speed

Filters

Provides information on 3-stage filtering to reduce reading noise.

7 Relative and Math

Math Operations

Details math (FCTN) operations: power, offset ohms, varistor, etc.

9 Sweep Operation

Configuring and Running a Sweep

Discusses setup, configuration, delay setting, and performing sweeps.

10 Triggering

Trigger Model

Discusses trigger model, layers, event detection, delay, and device action.

Configuring Triggering

Details how to configure various triggering aspects.

Remote Triggering

Details remote trigger model, commands, and basic triggering example.

11 Limit Testing

Types of Limits

Discusses three limit types: compliance, coarse, fine; summarizes grading and sorting modes.

Configuring and Performing Limit Tests

Describes configuration for limit tests and typical test procedure.

Remote Limit Testing

12 Digital I/O Port, Interlock, and Output Configuration

Digital I/O Port

Safety Interlock

Describes using Digital I/O Port as a safety interlock.

Front Panel Output Configuration

14 Status Structure

Programming and Reading Registers

Status Byte and Service Request (SRQ)

Explains programming Status Byte for SRQs and using serial poll to detect SRQs.

15 Common Commands

Command Summary

Lists IEEE-488.2 common commands used by the SourceMeter.

Command Reference

Provides detailed reference for common commands, excluding status structure.

16 SCPI Signal-Oriented Measurement Commands

Command Summary

Configuring Measurement Function

Provides detailed info on commands to configure measurement function.

Acquiring Readings

Describes commands to acquire post-processed readings, trigger, acquire, and single measurement.

17 SCPI Command Reference

18 Performance Verification

Verification Test Requirements

Recommended Test Equipment

Performing the Verification Test Procedures

Details restoring factory defaults, setting ranges, and output values.

Mainframe Verification

Covers procedures to verify mainframe accuracy alone.

19 Calibration

Recommended Calibration Equipment

Unlocking Calibration

Mainframe Calibration

Includes procedures to calibrate the mainframe without the Remote PreAmp.

20 Routine Maintenance

Line Fuse Replacement

Covers procedure and part numbers for replacing the line fuse.

Front Panel Tests

F Measurement Considerations

Floating measurement safety concerns

Discusses safety concerns for measurements up to 42V above chassis ground.

Low current measurements

Leakage currents and guarding

Explains reducing leakage currents using insulators, humidity control, and guarding.