User manual

Series 3700 System Switch/Multimeter Reference Manual Section 7: Buffer: Data Storage and Retrieval
3700S-901-01 Rev. C / July 2008 7-13
Attribute
Description
appendmode
When off, a new measurement to this buffer will clear the previous
contents before storing the new measurement. When 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 over the bus.
However, the default is on for the front panel or web interface to allow
triggered readings to fill a buffer without clearing the previous ones.
collectchannels
When on, channel or channel pattern information is stored with
readings in the buffer. This requires eight extra bytes of storage per
reading.
This value, off or on, can only be changed when the buffer is empty
(cleared). When the buffer is created, this attribute is initialized to on.
collecttimestamps
When on, time stamps will be stored with readings in the buffer. This
requires eight extra bytes of storage per reading.
This value, off or on, can only be changed when the buffer is empty
(cleared). When the buffer is created, this attribute is initialized to on.
Buffer read-only attributes
Use buffer read-only attributes to access the information contained in an existing
buffer. The following attributes are available per reading buffer (for example,
rb.basetimeseconds would access basetimeseconds for reading buffer
rb, and the number of readings the reading buffer can store is accessed as
rb.capacity).
Attribute
Description
basetimefractional
The fractional portion of the time stamp of when the reading at
rb[1] was stored in the reading buffer (in seconds).
basetimeseconds
The seconds portion of the time stamp, in whole seconds, when the
reading at rb[1] was stored in the buffer.
capacity
The total number of readings that can be stored in the reading buffer.
timestampresolution
The time stamp resolution, in seconds. The resolution is fixed at 1e-9
seconds.
Buffer programming examples
Refer to the following for buffer control programming examples. In the example,
the buffer is named readingbuffer.
NOTE You must clear the buffer using the readingbuffer.clear()
command before changing buffer control attributes.