Burst Mode; Available Functions In Burst Mode; Table - Keithley 2002 User Manual

Front Panel Operation

Table 2-30

Available functions in burst mode

Function
DC voltage
AC voltage
DC current
AC current
2-wire resistance
If these changes are not made, a "Settings conflict" error or
similar message is displayed when you attempt to turn on

burst mode.

When burst mode is selected, the Model 2002 is automati-
cally configured for taking fast measurements. (The instru-
ment's previous settings are restored when burst mode is
aborted.) Selecting burst mode makes these temporary
changes:
• Triggers are idled between bursts.
• Autoranging is disabled.
• Autozero is disabled.
• Integration time is set to 0.01 PLC (167µsec).
• Resolution is fixed at 4.5 digits.
• Buffer data group is set to compact.
• Buffer control is set to fill-and-stop.
Some instrument settings allowed in burst
mode, such as a trigger event source of
timer in the measure layer, may affect the
acquisition speed of 2000 readings/
second.
Enabling burst mode
Once burst mode is enabled, the instrument is dedicated to
that purpose. Other than setting the buffer size, you cannot
change any configuration parameters until burst mode is
aborted.
Thus, make sure to configure the instrument's function,
range and triggering to be compatible with burst mode before
enabling it. An incompatible configuration causes a "Set-
tings conflict" error when you try to enable burst mode.
Burst mode is enabled through the CONFIG DATA STORE
menu. This menu us displayed by pressing CONFIG and
2-66
Type
Normal
RMS, average
Normal
RMS, average
Normal
NOTE
then STORE. Rules for navigating menu structures are pro-
vided in paragraph 2.3.4.
BURST-MODE
This CONFIG DATA STORE menu selection is used to
enable or disable the burst mode:
OFF: Selecting this menu item returns the instrument to the
CONFIG DATA STORE menu.
ON: Select ON to enable burst mode. This action clears the
buffer, puts the unit into idle and takes it out of autorange.
The following typical message then prompts you for the
number of readings to store in the buffer:
BURST: 00100 READINGS
After ENTERing the desired buffer size, the following typi-
cal message will be displayed:
00100 READING BURST
Use TRIG to start; EXIT to abort
Burst mode operation
Table 2-31 details the sequence of steps during burst mode.
The steps assume just one burst of readings before aborting
the burst mode, but you are able to initiate more than one
burst, each time overwriting the previously stored readings.
As can be seen from the table, a front panel trigger starts the
burst acquisition. The Model 2002 remains looping in the
measure layer of the trigger model until the requested num-
ber of readings is acquired. To enhance burst acquisition
speed, the front panel is not updated until the raw readings
are being post-processed.
Meter Complete output pulses are sent at the rate of 2kHz
during the acquisition phase. (Note: The last one is not sent
until post-processing is done.)
After the acquisition phase, the unit returns to the idle state
and starts post-processing, which consists of converting the
raw readings into measurements by applying the calibration
constants. During the post- processing phase, the front panel
"*" annunciator is lit.
The acquisition phase of burst mode can be aborted by press-
ing the EXIT key. Then the Model 2002 starts post-process-
ing on that portion of the reading buffer.
Since burst mode turns off autozero, an autozero refresh is
required once every 24 hours (by changing functions, resolu-
tion, or issuing an autozero bus command).