Rel Remote Operation; Scanning - Keithley 3700 series Reference Manual

Section 5: Relative, Math, and dB
5. Apply the signal to be measured. The relative value will be subtracted from the next reading
that is triggered.
Pressing REL a second time disables REL. The user also has the option to manually enter a
REL level value rather than acquiring a value from an input signal. This can be done by
selecting the LEVEL item under the REL configuration menu using the front panel and entering
the value. REL will still need to be enabled by selecting the ENABLE menu item. A REL acquire
can also be done from this menu. Note that pressing the REL key is equivalent to doing an
acquire followed by enabling REL.
NOTE

REL remote operation

The dmm.rel.level() command specifies the REL value (for the active function only), while
the dmm.rel.acquire() command uses the input signal as the REL value (again, for the
active function only). The dmm.rel.acquire() command is typically used to zero the display.
For example, if the instrument is displaying a 1µV offset, sending dmm.rel.acquire() and
enabling REL (dmm.rel.enable = dmm.ON) zeros the display.
The following command sequence is equivalent to pressing the front panel REL key:
dmm.rel.acquire()
dmm.rel.enable=dmm.ON
To manually set a REL value of 1.5V, use this command sequence:
dmm.rel.level=1.5e-6
dmm.rel.enable=dmm.ON
For example:
If the instrument is on the DCV function, the dmm.rel.acquire() command is applicable to DCV
measurements.

Scanning

When a scan is configured, each channel can have its own unique rel value. For remote
programming, the <ch_list> parameter is used to configure channels for a scan.
For example: To attach a 1µV REL level to a desired configuration, send the following
commands:
Command
dmm.func = 'dcvolts'
5-2
You can perform the equivalent of REL manually using the mX+b math function. Set M
for 1 and B for any value you want. See the mX+b function (covered later in this
section).
Series 3700 System Switch/Multimeter Reference Manual
Description
Select DC volts function.
Document Number: 3700S-901-01 Rev. A / August 2007