Section 2: General operation
Model 2651A High Power System SourceMeter® Instrument Reference Manual
2-34
2651A-901-01 Rev. A / March 2011
Figure 9: 4-wire resistance sensing
Model 2651A
4-wire Sense HI
4-wire Sense LO
I
Input/Output HI
V
M
V
R
Test Current (I)
Resistance
Under Test
Lead
Resistances
R
S
R
LEAD
R
LEAD
= Current sourced by SourceMeter
= Voltage measured by SourceMeter
= Voltage across resistor
I
V
M
V
R
and measured resistance = =
V
M
I
V
M
Sense Current (pA)
Input/Output LO
R
LEAD
R
LEAD
Because sense current is negligible, =
V
M
V
R
I
V
R
= R
S
Sense selection
Front panel sense selection
To select sensing mode:
1. Press
the
CONFIG
key, and then press the
MEAS
key. Choose
V-MEAS
, and then press the
ENTER
key or the navigation wheel
.
2. Select
SENSE-MODE
, then press the
ENTER
key.
3. Select
2-WIRE
or
4-WIRE
, as desired, and then press the
ENTER
key or the navigation wheel
.
Remote sense selection
Use the
smua.sense
command to control sense selection by remote. The programming example
below illustrates how to enable 4-wire sensing:
smua.sense = smua.SENSE_REMOTE
See
Remote source-measure procedure
(on page 2-25) and
(on page 5-1) for
details.
Remote ohms programming
The following paragraphs summarize basic commands necessary for remote ohms programming and
also give a programming example for a typical ohms measurement situation.
