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Data Store
8-5
The timestamp is based on an oscillator with a frequency of approximately 8kHz. This oscil-
lator is used as the system clock and is divided by eight to generate system “ticks” every milli-
second. Therefore, the timestamp should provide lms resolution for test timing. However, since
the actual oscillator frequency is 8.192kHz, a system tick occurs every 8.192kHz/8 or 1024
times a second, which results in a system tick every 0.9765625ms. As a result, the reported
timestamp value is off by 24ms every second. Thus, to obtain more accurate timestamp values,
simply multiply the timestamp displayed on the front panel or returned via remote by a factor
of 0.9765625.
Buffer considerations
From the front panel, 2,500 source-measure readings can be stored and accessed using the
method described earlier in this section. Over the bus, however, there are actually two separate
2,500 reading buffers for a total of 5,000 readings. The :TRACe buffer is a 2,500 reading buffer
used by front panel data store, bus :TRACe commands, and to store sweep data, and it is bat-
tery backed-up. The READ? buffer is a separate 2,500 reading buffer that can only be accessed
over the bus using the :READ? command. You can store and access data from these two buffers
separately as outlined below.
Using :TRACe commands to store data
Use :TRAC:POIN <n> and :TRIG:COUN <n> followed by :TRAC:FEED:CONT NEXT to
store data. (n = number of readings; 2,500 maximum.) Turn on the output with :OUTP ON and
then send :INIT to take the unit out of idle and store readings. After data is stored, send
:TRAC:DATA? to access it. See Table 8-1 for a summary of these commands and
:TRACe sub-
system
in Section 17 for more details.
Using :READ? to store data
Use :TRIG:COUN <n> to set the number of readings to be stored. (n = number of readings;
2,500 maximum.) Turn on the output with :OUTP ON and then send the :READ? command to
trigger and access readings. (Once you access these readings, you will still be able to access
previously stored. :TRACe buffer readings using :TRAC:DATA?.) See Section 10 and
Trigger
subsystem
in Section 17 for triggering details, and Section 16 for information on the :READ?
command.
Summary of Contents for 6430
Page 26: ......
Page 32: ......
Page 78: ...2 14 Connections ...
Page 98: ...3 20 Basic Source Measure Operation ...
Page 138: ...5 30 Source Measure Concepts ...
Page 156: ...6 18 Range Digits Speed and Filters ...
Page 168: ...7 12 Relative and Math ...
Page 176: ...8 8 Data Store ...
Page 202: ...9 26 Sweep Operation ...
Page 248: ...11 22 Limit Testing ...
Page 310: ...16 6 SCPI Signal Oriented Measurement Commands ...
Page 418: ...17 108 SCPI Command Reference ...
Page 450: ...18 32 Performance Verification ...
Page 477: ...A Specifications ...
Page 489: ...B StatusandErrorMessages ...
Page 498: ...B 10 Status and Error Messages ...
Page 499: ...C DataFlow ...
Page 503: ...D IEEE 488BusOverview ...
Page 518: ...D 16 IEEE 488 Bus Overview ...
Page 519: ...E IEEE 488andSCPI ConformanceInformation ...
Page 523: ...F MeasurementConsiderations ...
Page 539: ...G GPIB488 1Protocol ...
Page 557: ......