Smux.buffer.getstats() - Keithley 2657A Reference Manual

Model 2657A High Power System SourceMeter® Instrument Reference Manual

smuX.buffer.getstats()

This function returns a specified reading buffer's statistics.
Type TSP-Link accessible
Yes
Function
Usage
statistics = smuX.buffer.getstats(bufferVar)
statistics
X
bufferVar
Details
This function returns a table with statistical data about the data that is placed in the buffer.
The SMU automatically updates reading buffer statistics as data is added to the reading buffer. When the
reading buffer is configured to wrap around and overwrite older data with new data, the buffer statistics include
the data that was overwritten.
The table returned from this function is a snapshot. Although the SMU continues to update the statistics, the
table returned is not updated. To get fresh statistics, call this function again.
The statistics parameter has the attributes described in the following table.
Attribute
n
mean
stddev
min
max
If n equals zero (0), all other attributes are nil. If n equals 1, the stddev attribute is nil because the standard
deviation of a sample size of 1 is undefined.
The min and max entries each have the attributes defined in the following table.
Attribute
measurefunction
measurerange
reading
sourcefunction
sourceoutputstate
sourcerange
sourcevalue
status
timestamp
2657A-901-01 Rev. B/December 2012
Affected by
The statistical data about the data in the reading buffer
Source-measure unit (SMU) channel (for example, smua.buffer.getstats()
specifies SMU channel A)
The reading buffer to process
When returned Description
Always The number of data points on which the statistics are based
When n > 0 The average of all readings added to the buffer
The standard deviation of all readings (samples) added to the buffer
When n > 1
When n > 0 A table containing data about the minimum reading value added to the buffer
A table containing data about the maximum reading value added to the buffer
When n > 0
Description
String indicating the function that was measured for the reading (current, voltage,
ohms or watts)
The full-scale range value for the measurement range used when the measurement
was made
The reading value
String indicating the source function at the time of the measurement (current or
voltage)
String indicating the state of the source (off or on)
Full-scale range value for the source range used when the measurement was made
If bufferVar.collectsourcevalues is enabled, the sourced value in effect at
the time of the reading
Status value for the reading; the status value is a floating-point number that encodes
the status value into a floating-point value
If bufferVar.collecttimestamps is enabled, the timestamp, in seconds,
between when the reading was acquired and when the first reading in the buffer was
acquired; adding this value to the base timestamp will give the actual time the
measurement was acquired
Section 7: TSP command reference
Where saved Default value
7-177