Section 7: TSP command reference
Model 2657A High Power System SourceMeter® Instrument Reference Manual
7-18
2657A-901-01 Rev. B/December 2012
Details
Assigning a value to this attribute enables or disables the reading buffer cache. When enabled, the reading
buffer cache improves access speed to reading buffer data.
If you run successive operations that overwrite reading buffer data, the reading buffer may return stale cache
data. This can happen when initiating successive sweeps without reconfiguring the sweep measurements or
when overwriting data in the reading buffer by setting the
bufferVar
.fillmode
attribute to
smu
X
.FILL_WINDOW
. To avoid this, make sure that you include commands that automatically invalidate the
cache as needed (for example, explicit calls to the
bufferVar
.clearcache()
function) or disable the cache
using this attribute (
bufferVar
.cachemode
).
Example
smua.nvbuffer1.cachemode = 1
Enables reading buffer cache of
dedicated reading buffer 1.
Also see
(on page 7-19)
(on page 3-6)
bufferVar.capacity
This attribute contains the capacity of the buffer.
Type
TSP-Link accessible
Affected by
Where saved
Default value
Attribute (R)
Yes
Not applicable
See
Details
Not
applicable
Usage
bufferCapacity
=
bufferVar
.capacity
bufferCapacity
The maximum number of readings the buffer can store
bufferVar
The reading buffer; can be a dynamically allocated user-defined buffer or a
dedicated reading buffer
Details
This read-only attribute reads the number of readings that can be stored in the buffer.
For dedicated reading buffers, all buffer attributes are saved to nonvolatile memory only when the reading buffer
is saved to nonvolatile memory.
The buffer's capacity does not change as readings fill the buffer. A dedicated reading buffer that only collects
basic items can store over 140,000 readings. Turning on additional collection items, such as timestamps and
source values, decreases the capacity of a dedicated reading buffer (for example,
smua.nvbuffer1
), but does
not change the capacity of a user-defined dynamically allocated buffer. A user-defined dynamically allocated
buffer has a fixed capacity that is set when the buffer is created.
See the
smu
X
.nvbuffer
Y
attribute for details on accessing dedicated reading buffers. See the
smu
X
.makebuffer()
function for information on creating user-defined dynamically allocated reading buffers.
Example
bufferCapacity = smua.nvbuffer1.capacity
print(bufferCapacity)
Reads the capacity of dedicated reading
buffer 1.
Output:
1.05
The above output indicates that the buffer
can hold 149789 readings.
Summary of Contents for 2657A
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