Sense And Sample Buffer - Keithley 2750 User Manual

D-8 Signal Processing Sequence and Data Flow
NOTE

SENSe and sample buffer

The TRACe:CLEar command clears the data store, INITiate:CONTinuous OFF command
disables continuous initiation, and TRIGger:COUNt 1 configures the instrument to per-
form one measurement cycle. The INIT command can then be used to initiate the mea-
surement cycle. When the INIT command is sent, the programmed number of
measurements (set by the SAMPle:COUNt command) are performed and the respective
data is temporarily stored in the sample buffer.
For example, if 20 measurements were performed (SAMP:COUN 20), then 20 data arrays
will be stored in the sample buffer. Data from this buffer is then routed to other enabled
data flow blocks. The data in the sample buffer remains there until data from another mea-
surement cycle overwrites the buffer.
NOTE
For the following discussion, a "data array" is defined as the group of data ele-
ments that are included with each measured reading. Each data array includes
the reading as well as the channel, reading number, units, timestamp, and limits
result (see "FORMat:ELEMents <item list>," page
For example, assume the selected data elements to be returned by a read com-
mand include the reading, units designator, and reading number. Now assume a
1VDC input and the READ? command is sent to trigger two readings and return
the two data arrays. The two returned data arrays would look like this:
+1.00000000E+00VDC, +00000RDNG#, +1.00000000E+00VDC. +00001RDNG#
(Data Array #1)
The trigger count (TRIG:COUN) determines how many measurement cycles are
performed. However, only the data arrays for the last measurement cycle end up
in the sample buffer. For example, assume TRIG:COUN 2 and SAMP:COUN 20.
The first measurement cycle stores 20 data arrays in the sample buffer. The sec-
ond measurement cycle then overwrites the 20 data arrays in the sample buffer.
Model 2750 Multimeter/Switch System User's Manual
14-5, for details).
(Data Array #2)