Tektronix Keithley SourceMeter 2470, Reference Manual

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Section 6: Reading buffers 2470 High Voltage SourceMeter Instrument Reference Manual
6-10 2470-901-01 Rev. A /
May
2019
Setting reading buffer capacity
The capacity of a reading buffer determines how many readings the buffer holds. You can change the
capacity of reading buffers.
Stored readings and statistics are deleted when you change the capacity of a buffer.
For user-defined buffers, you assign a capacity when you create the reading buffer. For default
buffers (
defbuffer1
and
defbuffer2
), the initial buffer size is 100,000 readings.
The buffer style you choose when you create the reading buffer affects the capacity of the reading
buffer. The compact buffer style stores more readings with lower resolution and less reading
information. For more information about buffer styles and their capacities, see Creating buffers (on
page 6-5).
The buffer fill mode affects the capacity of the reading buffer. For example, if the reading buffer fill
mode is set to fill once, when the buffer reaches capacity, no more readings are made and event
code 4915, "Attempting to store past capacity of reading buffer" is displayed. If a buffer that is set to
fill once is partially filled and a new reading count is set that exceeds the remaining capacity of the
buffer, the new reading count is lowered so that the capacity is not exceeded. For more information
on fill modes, see Setting the fill mode (on page 6-12).
The capacity of a new reading buffer is affected by the capacity of all other buffers defined in the
instrument. All buffers in the instrument share a finite amount of space; the total capacity of those
buffers combined defines the remaining space that can be allocated to a new buffer. If you try to
define a buffer that uses more space than the remaining space to be allocated, you will receive an
event message. If this happens, try defining a smaller capacity for the buffer.
To increase the amount of space available for buffers, delete user-defined reading buffers that you
are not using or reduce the capacity of existing reading buffers. This clears existing data in the buffer
you change. Power cycling the instrument deletes all user-defined buffers in the instrument.
The overall capacity of all buffers stored in the instrument cannot exceed 5,000,000 readings for
standard reading buffers and 21,000,000 for compact reading buffers.
The following topics describe how to set the reading buffer capacity.
Using the front panel to set buffer capacity:
When you resize a reading buffer, data in the buffer is cleared.