Front Panel Operation
2-97
COUNT
With this menu selection, you specify the number of read-
ings to store.
ENTER-COUNT: This item allows you to specify the buffer
size in number of readings. The maximum buffer size is sum-
marized in Table 2-22.
The minimum buffer size is one reading. Note that with only
one reading stored in the buffer, the buffer math operations
(MIN, MAX, StdDev) may not be useful or may not return
valid data.
USE-TRIGGER-MODEL: This selection lets you default to
the measure count in the present trigger configuration, as
long as the measure count is a finite value.
CONTROL
This menu item controls the type of data storage.
FILL-AND-STOP: This control selection fills the buffer
with the requested number of readings and stops. You can
then recall the readings.
PRETRIGGER: This selection continuously stores readings
until a user-programmed trigger event occurs. It then stores
post-trigger readings. For example, with a buffer size of 100
readings, there can be 50 readings stored before the trigger
event and 50 readings stored after the trigger. The first read-
ing after the trigger is reading zero. Pretrigger readings have
reading numbers and relative time-stamps with a minus sign;
post-trigger readings have reading numbers and relative
time-stamps with a plus sign. After selecting PRETRIG-
GER, configure pretrigger control further as follows:
• PERCENTAGE or READING-COUNT — Specify the
number of readings to store before the trigger event as a
percentage of the total number of stored readings, or as
a number of pretrigger readings. You will be prompted
to enter the percentage or count value.
• EVENT — Selects the source of the pretrigger or
“mark-point” event. This can be a Manual, GPIB, Trig-
ger Link or External trigger.
CONTINUOUS: With this control selection, readings are al-
ways stored in the buffer. The process continues, with the
oldest readings being overwritten in a circular manner, until
storage is interrupted with the EXIT key.
NEVER: Gets set to this if data storage has been interrupted.
Pressing the STORE key changes NEVER to FILL-AND-
STOP.
CLEAR-ALL
This action (yes or no) can be used at any time to clear the
data buffer of all stored readings and buffer statistics.
TIMESTAMP
A timestamp is included with each buffer reading if it is se-
lected as a data element (see ELEMENTS). This menu selec-
tion is used to check and/or change the timestamp type and
format.
TYPE: This menu item is used to check and/or change the
timestamp type. Note that changing the timestamp type
clears the buffer.
• RELATIVE-TIME — With this selection, timestamps
are oriented to a timer with the first buffer reading
timestamped at 0.000000 seconds. Each following
timestamp is then based on the currently selected for-
mat (see FORMAT). With the ABSOLUTE format se-
lected, the timestamp for each reading is referenced (in
seconds) to the first buffer reading. With the DELTA
format selected, each timestamp is referenced (in sec-
onds) to the previous timestamp.
• REAL-TIME — With this selection, timestamps are
oriented to the real-time clock and are based on the cur-
rently selected format (see FORMAT). With the ABSO-
LUTE format selected, each reading is simply
timestamped with the actual time and date. Time can be
expressed in the 12-hour (AM, PM) format or the 24-
hour format (see CLOCK in paragraph 2.19.8).
With the DELTA format selected, the first buffer reading is
timestamped at 00000d 00h 00m 00.00s (zero days, hours,
minutes and seconds). Each subsequent timestamp is refer-
enced (in days, hours, minutes and seconds) to the previous
timestamp.
Timestamp type for buffer readings is coupled to timestamp
type for bus readings. Thus, if you change timestamp type
from this menu structure, it also changes in the MAIN
MENU structure (see TIMESTAMP in paragraph 2.19.8).
FORMAT: This menu item is used to check and/or change
the timestamp format. Note that if format is changed after
readings are stored in the buffer, the timestamps will change
to reflect the alternate format.
• ABSOLUTE — With this selection, each timestamp
provides the time and date that the reading was taken
(see REAL-TIME timestamp type), or the number of
seconds from the first buffer reading that the reading
was taken (see RELATIVE-TIME timestamp type).
