Keithley 2461 Reference Manual

Section
2: General operation Model 2461 Interactive SourceMeter® Instrument
Reference Manual
2-94 2461-901-01 A/November 2015
Using TSP commands:
To change to 4-wire sensing, send these commands:
smu.measure.func = smu.FUNC_DC_VOLTAGE
smu.measure.sense = smu.SENSE_4WIRE
To assign a different measure function, replace smu.FUNC_DC_VOLTAGE with one of the following:
• For current measurements: smu.FUNC_DC_CURRENT
• For resistance measurements: smu.FUNC_RESISTANCE
Ohms measurements
You can make ohms measurements using either 2-wire or 4-wire sensing.
Accuracy of 2-wire resistance measurements
The 2-wire sensing method has the advantage of requiring only two test leads. However, as shown in
the following figure, the total lead resistance is added to the measurement. This can seriously affect
the accuracy of 2-wire resistance measurements, particularly with low resistance values.
Figure 63: Two-wire resistance sensing for a high impedance DUT
Measured resistance:
Actual resistance:

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