2600AS-901-01 Rev. B / September 2008
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19-13
Series 2600A System SourceMeter® Instruments Reference Manual
Section 19: Remote Commands
Reading buffers
Readings can be obtained in multiple ways. Reading acquisition can be synchronous or
overlapped. Furthermore, the routines that make single point measurements can be configured to
make multiple measurements where only one would ordinarily be made. Also, consider that the
measured value is not the only component of a reading. The measurement status (for example “In
Compliance” or “Over ranged”) is also data associated with a particular reading.
All routines that return measurements can return them in reading buffers. Overlapped
measurements are always returned in a reading buffer. Synchronous measurements return a
single value or both a single value and a reading buffer. The more advanced user can use the
reading buffer to access the additional information stored in the reading buffer.
A reading buffer is based on a TSL table. The measurements themselves are accessed by
ordinary array access. If
rb
is a reading buffer, the first measurement is accessed as
rb[1]
and
the 9
th
measurement as
rb[9]
, etc. The additional information in the table is accessed as
additional members of the table. The following values are all available per reading buffer, i.e.,
rb.appendmode
:
The following values are available per reading, i.e.,
rb.measurefunctions[3]
, as enabled.
Each is actually a nested table. Related entries are stored at the same index as the relevant
measurement.
appendmode
Off or on. If off, a new measurement to this buffer will overwrite
the previous contents. If 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.
basetimestamp
The time stamp of when the reading at
rb[1]
was stored, in
seconds, since 12:00 am January 1, 1970 (UTC).
capacity
The total number of readings that can be stored in the reading
buffer.
collectsourcevalues
When on, source values will be stored with readings in the
buffer. This requires four extra bytes of storage per reading.
This value, off or on, can only be changed when the buffer is
empty. When the buffer is created, this attribute is initialized to
off.
collecttimestamps
When on, time stamps will be stored with readings in the buffer.
This requires four extra bytes of storage per reading. This value,
off or on, can only be changed when the buffer is empty. When
the buffer is created, this attribute is initialized to off.
n
The number of readings in the reading buffer.
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.
measurefunctions
An array (TSL table) of strings indicating the function measured
for the reading (Current, Voltage, Ohms or Watts).
measureranges
An array (TSL table) of full-scale range values for the measure
range used when the measurement was made.
readings
An array (TSL table) of the readings stored in the reading buffer.
This array holds the same data that is returned when the
reading buffer is accessed directly, i.e.,
rb[2]
and
rb.readings[2]
are the same value.
sourcefunctions
An array (TSL table) of strings indicating the source function at
the time of the measurement (Current or Voltage).