3-20
Basic DMM Operation
Model 2701 User’s Manual
Resistance measurements (
Ω
2 and
Ω
4)
The Model 2701 has seven ohms ranges to measure resistance from 100µ
Ω
to 120M
Ω
.
Available measurement ranges include 100
Ω
, 1k
Ω
, 10k
Ω
, 100k
Ω
, 1M
Ω
, 10M
Ω
, and 100M
Ω
.
Information for this topic is structured as follows:
•
Connections
—
2-wire or 4-wire connections can be made to the front panel input
terminals of the mainframe or to a switching module (such as the Model 7700).
•
Standard resistance measurements — The Model 2701 can make resistance
measurements from 100µ
Ω
to 120M
Ω
. For resistances >1k
Ω
, the
Ω
2 function
(2-wire) is typically used for measurements. For resistances
≤1
k
Ω
, the
Ω
4 function
(4-wire) is typically used. The
Ω
4 function should be used to cancel the effect of
test lead (and channel path) resistances.
•
Offset-compensated ohms (OCOMP) — The presence of thermal EMFs (voltages)
can adversely affect low-resistance measurement accuracy. To overcome these
unwanted offset voltages, you can use offset compensated ohms on the 100
Ω,
1k
Ω,
and 10k
Ω
ranges for the
Ω
4 function.
•
Measurement methods
— For the 100
Ω
to 1M
Ω
ranges, the Model 2701 uses the
constant-current method to measure resistance. The Model 2701 sources a constant
current (I) to the resistance and measures the voltage (V). Resistance (R) is then
calculated (and displayed) using the known current and measured voltage (R = V/
I). For the 10M
Ω
and 100M
Ω
ranges, the ratiometric method is used to measure
resistance.
•
4-wire common-side (CSID) ohms measurements
— Explains the CSID ohms
mode which is used with the 7701 module to perform 4-wire common-side ohms
measurements.
Connections
NOTE
When using the front panel inputs, the INPUTS switch must be in the “F” (out)
position. For switching modules, it must be in the “R” (in) position.
Front panel inputs
Connections for resistance measurements are shown in Figure 3-8. For 2-wire resistance
measurements (
Ω
2), connect the test leads to INPUT HI and LO as shown in Figure 3-8A.
For 4-wire resistance (
Ω
4), connect the test leads to INPUT HI, INPUT LO, SENSE
Ω
4
HI, and SENSE
Ω
4 LO as shown in Figure 3-8B.
2701-900-01.book Page 20 Wednesday, August 3, 2011 9:43 AM
Summary of Contents for 2701
Page 344: ...12 CommonCommands 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...
Page 366: ...15 SCPIReferenceTables 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...
Page 393: ...A Specifications 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...
Page 399: ...B Model7700ConnectionGuide 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...
Page 410: ...C StatusandErrorMessages 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...
Page 417: ...D SignalProcessing SequenceandDataFlow 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...
Page 430: ...E MeasurementConsiderations 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...
Page 450: ...G KE2700InstrumentDriver Examples 2701 900 01 book Page 1 Wednesday August 3 2011 9 43 AM...