Table 7-2
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 requires 4 extra bytes of storage per reading. This value, off or
on, can only be changed when the buffer is empty. When the buffer is cre-
ated, this attribute is initialized to off.
collecttimestamps
When this attribute is on, time stamps will be stored with readings in the
buffer. This requires 4 extra bytes of storage per reading. This value, off or
on, can only be changed when the buffer is empty. When the buffer is cre-
ated, this attribute is initialized to off.
timestampresolution
The time stamp resolution, in seconds. When the buffer is created, its initial
resolution is 0.000001 seconds. At this resolution, the reading buffer can
store unique time stamps 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 7-3
Buffer read-only attributes
Storage attribute
Description
basetimestamp
The time stamp of when the reading at rb[1] was stored, in seconds from
power-up.
capacity
The total number of readings that can be stored in the reading buffer.
n
The number of readings in the reading buffer.
Table 7-4
Buffer control programming examples
Command
Description
smua.nvbuffer1.collectsourcevalues = 1
Enable source value storage.
smua.nvbuffer1.appendmode = 1
Enable buffer append mode.
smua.nvbuffer1.collecttime stamps = 0
Disable time stamp storage.
smua.nvbuffer1.timestampresolution = 0.001
Set time stamp resolution to 0.001s.
Table 7-5
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.
7-6
Return to
2600S-901-01 Rev. C / January 2008
Section 7: Buffer (Data Store)
Series 2600 System SourceMeter® Instruments Reference Manual
Buffer reading attributes
Attributes that control which elements are recalled from the buffer are listed in
. To access
specific elements, simply append the desired attribute to the buffer designation.
For example, the following would return 100 Channel A readings from buffer 1:
printbuffer(1, 100, smua.nvbuffer1.readings)
