Keithley 2657A User Manual

Section 7: TSP command reference Model 2657A High Power System SourceMeter® Instrument Reference Manual
7-20 2657A-901-01 Rev. B/December 2012
Details
This function clears all readings from the specified cache.
If you run successive operations that overwrite reading buffer data, the reading buffer may return stale cache
data. This can happen when you:
• Initiate successive sweeps without reconfiguring the sweep measurements. Watch for this when running
Lua code remotely on more than one node, because values in the reading buffer cache may change
while the Lua code is running.
• Overwrite data in the reading buffer by setting the bufferVar.fillmode attribute to
smuX.FILL_WINDOW.
To avoid this, you can include explicit calls to the bufferVar.clearcache() function to remove stale values
from the reading buffer cache.
Example
smua.nvbuffer1.clearcache()
Clears the reading buffer cache for
dedicated reading buffer 1.
Also see
bufferVar.cachemode (on page 7-17)
bufferVar.fillmode
(on page 7-22)
Reading buffers
(on page 3-6)
Removing stale values from the reading buffer cache
(on page 6-60)
smuX.nvbufferY
(on page 7-210)
bufferVar.collectsourcevalues
This attribute sets whether or not source values will be stored with the readings in the buffer.
Type TSP-Link accessible Affected by Where saved Default value
Attribute (RW) Yes Not applicable See Details 0 (disabled)
Usage
state = bufferVar.collectsourcevalues
bufferVar.collectsourcevalues = state
state
Source value collection status; set to one of the following:
• 0: Source value collection disabled (off)
• 1: Source value collection enabled (on)
bufferVar
The reading buffer; can be a dynamically allocated buffer (user-defined), or a
dedicated reading buffer (such as smua.nvbuffer1)
Details
Assigning a value to this attribute enables or disables the storage of source values. Reading this attribute returns
the state of source value collection. This value can only be changed with an empty buffer. Empty the buffer using
the bufferVar.clear() function.
For dedicated reading buffers, all buffer attributes are saved to nonvolatile memory only when the reading buffer
is saved to nonvolatile memory.
When on, source values will be stored with readings in the buffer. This requires four extra bytes of storage for
each reading. Turning on additional collection items, such as source values (this attribute) and timestamps,
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.

Keithley 2657A Specifications

General

Brand	Keithley
Model	2657A
Category	Measuring Instruments
Language	English