Keithley 2790, User Manual, Page: 32 / 130

Model 2790 SourceMeter
®
Switch System User’s Manual 2-11
Front panel operation
An ohms math function is enabled from the MATH menu, which is accessed by pressing
and releasing SHIFT and then MATH (see
Figure 2-3 ). Note that an ohms math function is
only available in the menu if the associated 7751, 7752, or 7753 module is installed.
Figure 2-3
Enabling ohms math function
Remote programming
As shown in Table 2-2 , the :CALC:FORMat command is used to select an ohms math
function. Notice that the math setting can be global to all qualified channels or set on a
per-channel basis by using the <clist> parameter.
NOTE
With an ohms math function selected, the Model 2790 is actually measuring
DCV. Therefore, if you send SENS1:FUNC? to query the selected function, it
will return “VOLT:DC”.
Source tracking
The Model 2790 provides source tracking to ensure that the most recently set source
amplitude is used in the selected ohms calculation. If the source output level changes, the
“m” constant for the calculation will change accordingly.
Source tracking is enabled automatically when the desired ohms function is selected. No
other actions are required by the user.
However, if desired, source tracking can be disabled or the source that is being tracked can
be changed. The :TRACk and :SOURCe commands are listed in
Table 2-2 .
SHIFT
Press
Press
Select math
function
S1IOHMS S1VOHMS S2IOHMS S2VOHMS
MATH
7751/7753
in slot 1
7751/7752/7753
in slot 1
7751/7752/7753*
in slot 2
7751/7753*
in slot 2
* 7753 should be installed in slot 1 for rated accuracy.