Keithley 2001 Operator's Manual page 71

q~ÄäÉ=PJNV
 
2 and 4 auto filter
2-wire resistance
4-wire resistance
RESOLUTION
The RESOLUTION parameter sets the display resolution. It
is discussed in paragraph
the differences for 2 and 4 are noted here.
The available resolution on all resistance functions and types
is 3.5 digits to 7.5 digits. If the 2 or 4 resolution is AUTO,
refer to Table 3-20 for the resolution associated with the
integration time.
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 
2 and 4 auto resolution
0.01 to <0.02 PLC
0.02 to <0.20 PLC
0.20 to <2.00 PLC
2.00 to 10.00 PLC
Note: If the resolution is AUTO and the integration time
SET-BY-RSLN, the resolution will be 6.5 digits and the
integration time 1.0 PLC.
OFFSETCOMP
Offset compensation is used to compensate for voltage
potentials, such as thermal offsets, across the device under
test. This feature eliminates errors due to a low level external
voltage source configured in series with the unknown
resistor. Offsets up to ±0.2V on the 20 and 200 ranges,
and from -0.2V to +2V on the 2k and 20k ranges can be
corrected with offset compensation. Offset compensation is
available for 2- and 4-wire resistance measurements.
During offset compensated resistance measurements, the
Model 2001 performs the following steps for each A/D
conversion:
1. Makes a normal resistance measurement of the device.
In general, this consists of sourcing a current through the
device, and measuring the voltage drop across the
device.
2001-900-01 Rev. K/ August 2010
On Advanced
On Advanced
3.4.1, DC and AC voltage. Only
4.5d
5.5d
6.5d
7.5d
10 1.0%
10 1.0%
2. Turns off the internal current source and again measures
the voltage drop across the device. This is the voltage
caused by an external device.
3. Calculates and displays the corrected resistance value.
Offset compensation not only corrects for small error
voltages in the measurement circuit, but it also compensates
for thermal voltages generated within the Model 2001. In
normal mode ohms, these thermal EMF offsets are
accounted for during calibration.
You can enable/disable offset compensation as follows:
1. From the CONFIGURE OHMS-2W or CONFIGURE
OHMS-4W menu, select OFFSETCOMP and press EN-
TER. The following menu is displayed:
SET OFFSET COMP
ON OFF
2. Highlight the desired selection and press ENTER.
Offset compensated readings are indicated by "OCmp" to
the right of the reading.
Note that the offset compensation settings of the ohms
functions are discrete. Thus, enabling offset compensation in
2-wire ohms has no effect on 4-wire ohms.
MAXAUTORANGE
By setting an upper limit on autoranging, you can prevent
changes to ranges that you do not want to use. This speeds up
the reading rate while still using auto-ranging. You can
program the MAXAUTORANGE as follows:
1. From the CONFIGURE OHMS-2W or CONFIGURE
OHMS-4W menu, select MAXAUTORANGE and
press ENTER. One of the following menus is displayed:
SET 2 MAX AUTORANGE
1G 200M 20M 2M 200k 20k
or
SET 4 MAX AUTORANGE
200k 20k 2k
Front Panel Operation
Moving
Moving
3-39