Buffervar.capacity - Keithley 2601B Reference Manual

Series 2600B System SourceMeter® Instrument Reference Manual
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
smuX.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
Also see
bufferVar.clearcache()
bufferVar.fillmode
Reading buffers

bufferVar.capacity

This attribute contains the capacity of the buffer.
Type TSP-Link accessible
Attribute (R) Yes
Usage
bufferCapacity = bufferVar.capacity
bufferCapacity
bufferVar
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 smuX.nvbufferY attribute for details on accessing dedicated reading buffers. See the
smuX.makebuffer() function for information on creating user-defined dynamically allocated reading buffers.
2600BS-901-01 Rev. B / May 2013
(on page 7-18)
(on page 7-22)
(on page 3-6)
Affected by
Not applicable
The maximum number of readings the buffer can store
The reading buffer; can be a dynamically allocated user-defined buffer or a
dedicated reading buffer
Section 7: TSP command reference
Enables reading buffer cache of
dedicated reading buffer 1
(source-measure unit (SMU)
channel A).
Where saved
See Details
Default value
Not applicable
7-17