Keithley 2461 Reference Manual

Model 2461
Interactive SourceMeter® Instrument Reference Manual Section 2:
General operation
2461-901-01 A/November 2015 2-105
Making resistance measurements
When you make resistance measurements, the resistance is calculated by either sourcing current
and measuring voltage or by sourcing voltage and measuring current.
When source readback is on, the instrument measures both voltage and current and uses these
values in the ohms calculations. When source readback is off, the instrument uses the programmed
source value and the measured value in the ohms calculations. Note that the measured source value
is more accurate than the programmed source value, so measurements made with source readback
on are more accurate.
When you are measuring resistance, you can set the offset-compensated ohms option.
Resistance measurement methods
From the front panel, you can use one of the following methods to measure resistance with the Model
2461:
• Press FUNCTION and select source current and measure resistance
• Press FUNCTION and select source voltage and measure resistance
• Press QUICKSET and select Ohmmeter. When Ohmmeter is selected, the source current and
source limit are set automatically.
From a remote interface, you can use one of following methods to measure resistance with the Model
2461:
• Source voltage, measure current, and set measure units to ohms
• Source current, measure voltage, and set measure units to ohms
• Set the measure function to resistance. When the measure function is set to resistance, the
instrument sets the source current and source limit automatically.
Each of these methods is described in the following topics.
Source voltage, measure current, and read ohms
If you want to make resistance readings by sourcing voltage and measuring current, you can use this
method.
The examples below use a 100 kΩ device under test. The code:
• Makes five readings by sourcing 5 V
• Measures current with autorange enabled
• Sets the measure units to ohms
• Uses offset compensation
• Retrieves the source and measure values
Even though the measurement units are in ohms, the measurement range is 10 µA.

Keithley 2461 Specifications

General

Maximum Current	7 A
Power	100 W
Resolution	6.5 digits
Source Measure Unit (SMU)	Yes
DC Voltage	100 V
Maximum Voltage	100 V
Display	5-inch capacitive touchscreen
Connectivity	USB, GPIB
Software	TSP
DC Current	7 A
Current Source Range	0 to 7 A
Voltage Measurement Range	100 mV to 100 V
Current Measurement Range	10 nA to 7 A
Voltage Measurement Resolution	100 nV