IEEE-488 Reference
4-89
#0, stored in the buffer. If using Pre-trigger to store readings, the pre-trigger readings will be as-
signed negative numbers.
UNITs: This element attaches the function unit to the reading, the time unit (sec) to the
timestamp, and the channel unit (internal or external) to the channel number. An internal channel
refers to an internally installed switching card (such as the Model 2001 SCAN) channel, while
an external channel refers to the channel from an external switch system. This element is not
available for the binary formats.
TIMEstamp: This is simply a timer that is used to reference each reading to a point in time. The
timer starts at zero seconds when the instrument is turned on. After 99,999.999999 seconds, the
timer will reset to zero seconds and start over. When a reading is sent over the bus (i.e. FETCh?),
the TIMEstamp element will indicate the time that the reading was taken. The instrument also
provides a time-stamp for readings stored in the buffer. When buffer readings are sent over the
bus (:TRACe:DATA?), the time-stamp for each reading will be referenced to the first reading,
which is time-stamped at 0 seconds, stored in the buffer. If using Pre-trigger to store readings,
each pre-trigger reading will have a negative time-stamp.
STATus: This element indicates if the reading is normal (N), overflowed (O) or referenced (R)
to another value. This element is not available for the binary formats.
The ASCII format shown in Figure 4-19 shows the byte order of the data string. Keep in mind
that the byte order can only be reversed for the binary formats.
When using this command to add an element, you must include all elements that you want in the
format. For example, if the reading is already specified and you want to add the time-stamp, you
must include the READing parameter.
:form:elem time, read
Data elements for the item list can be listed in any order, but are always sent in the order shown
in Figure 4-19.
NOTE
At power-on, all data elements will be selected. If the SCPI fetch for-
mat is selected (see :SYSTem:FORMat:ELEMents command), send-
ing *RST will select the READing element only.
Programming example 10 OUTPUT 716; “:form:elem read, stat, unit, time; elem?”
20 ENTER 716; A$
30 PRINT A$
40 END
Line 10 Two commands in this program message; the first selects four data elements, and the
second queries the elements.
Line 20 Addresses the Model 2001 to talk.
Line 30 Displays the elements (READ, UNIT, TIME, STAT).
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