Keithley 6487 Reference Manual

6-14 Buffer and Sweeps Model 6487 Reference Manual
C) :VOLTage:SWEep:STEP <NRf>
This command programs the step voltage. In cases where there are not an exact number of
steps between the start and stop point, the last step will be truncated. Step sizes larger than
the (stop - start) interval will generate Error -842 “Sweep step size too large”. Step sizes
that will result in a sweep with more than the 3,000 point buffer maximum or below the
minimum source resolution for the source range required by the sweep will also generate
Error +841 “Sweep step size too small”. The STEP size is an absolute value, so the lower
limit is zero and the upper limit is restricted by the STARt and STOP settings.
D) :VOLTage:SWEep:CENTer <NRf>
This command enters the mid-point of the sweep. Note that CENTer and SPAN are inti-
mately coupled with STARt and STOP and simply offer another way to specify the sweep.
E) :VOLTage:SWEep:SPAN <NRf>
This command enters the total span of the sweep. CENTer and SPAN are coupled with
STARt and STOP and are another way to specify the sweep.
F) :VOLTage:SWEep:DELay <NRf>
This command programs the delay period, which is the time that the Model 6487 waits
after sourcing the voltage before starting to take the measurement at each step.
G) :VOLTage:SWEep:INITiate
This command places the voltage source in operate and begins sweep operation with the
next trigger. Once the sweep is triggered, the buffer is opened and the unit begins saving
readings. Error checking is held off until the SOUR:VOLT:SWEep:INIT command is sent.
A step size that is too small and would result in more than 3,000 points in the sweep gen-
erates Error +841 “Sweep step size too small”. If the step size exceeds the interval (STOP
- STARt), then you get Error +842 “Sweep step size too large”.
H) :VOLTage:SWEep:ABORt
This command immediately places the voltage source in standby (Operate off), cancels
buffer storage, and restores the trigger model to its prior settings before the sweep was
started.
I) :VOLTage:SWEep:STATe?
This query provides a means to determine whether or not a sweep is still running. A
returned value of 1 indicates that the sweep is still in progress, while a value of 0 shows
that no sweep is active.

Keithley 6487 Specifications

General

Type	Picoammeter/Voltage Source
Current Measurement Range	20 fA to 20 mA
Interfaces	GPIB, RS-232
Voltage Burden	< 200 µV
Input Impedance	>10^14 Ω
Power	100 V / 120 V / 220 V / 240 V
Basic Current Measurement Accuracy	0.4%