Keithley 2600a series, Справочное руководство, Страница: 142 / 696

7-8 Return to Section Topics 2600AS-901-01 Rev. B / September 2008
Section 7: Reading Buffers Series 2600A System SourceMeter® Instruments Reference Manual
Reading buffer attributes
Use the reading buffer attributes to access the reading buffer data. Table 7-7 displays the
attributes that you can use to access the reading buffer data.
For example, the following would return 100 Channel A readings from Buffer 1:
printbuffer(1, 100, smua.nvbuffer1.readings)
Similarly, the following would return 100 Channel A source values from Buffer 1:
printbuffer(1, 100, smua.nvbuffer1.sourcevalues)
Table 7-3
Buffer storage control attributes
Storage attribute Description
appendmode
The append modes are either off or on. When the append mode is off, a new
measurement to this buffer will overwrite the previous contents. When the
append mode is on, the first new measurement will be stored at what was
formerly rb[n+1]. This attribute is initialized to off when the buffer is created.
collectsourcevalues
When this attribute is on, source values will be stored with readings in the
buffer. This value, off or on, can only be changed when the buffer is empty.
When the buffer is created, this attribute is initialized to off.
collecttimestamps
When this attribute is on, timestamps will be stored with readings in the
buffer. This value, off or on, can only be changed when the buffer is empty.
When the buffer is created, this attribute is initialized to off.
timestampresolution
The timestamp resolution, in seconds. When the buffer is created, its initial
resolution is 0.000001 seconds. At this resolution, the reading buffer can
store unique timestamps for up to 71 minutes. This value can be increased
for very long tests. Note: The minimum resolution setting is 1µs (0.000001
seconds).
Table 7-4
Buffer read-only attributes
Storage attribute Description
basetimestamp
The timestamp of when the reading at rb[1] was stored, in seconds from mid-
night January 1, 1970 GMT, see page
19-14 for additional details.
capacity
The total number of readings that can be stored in the reading buffer.
n
The number of readings in the reading buffer.
Table 7-5
Buffer control programming examples
Command Description
smua.nvbuffer1.collectsourcevalues = 1
Enable source value storage.
smua.nvbuffer1.appendmode = 1
Enable buffer append mode.
smua.nvbuffer1.collecttimestamps = 0
Disable timestamp storage.
smua.nvbuffer1.timestampresolution = 0.001
Set timestamp resolution to 0.001024s.
Table 7-6
Buffer read-only attribute programming examples
Command Description
number = smua.nvbuffer1.n
Request number of readings in buffer.
buffer_size = smua.nvbuffer1.capacity
Request buffer size.