Memory Formats - Agilent Technologies 3458A User Manual

Memory Formats

Note
1. The ASCII format is actually 15 bytes for the reading plus 1 byte per reading for a null character which is used
to separate stored ASCII readings only.
clearing any stored readings by sending:
OUTPUT 722;"MEM CONT"
Readings can be stored in one of five formats: ASCII, single integer (SINT),
double integer (DINT), single real (SREAL), or double real (DREAL). The
memory space required for each format is:
ASCII -
SINT -
DINT -
SREAL -
DREAL -
To determine how many readings can be stored using a particular format,
divide the reading memory size (first response returned by the MSIZE?
command) by the number of bytes per reading shown above.
•
Single Integer (SINT) or Double Intcgcr (DINT) Use the SINT memory
format when making low-resolution measurements (3.5 or 4.5 digits) at the
fastest possible rate on a fixed range (autorange disabled). (Since the SINT
format is only 2 bytes per reading, you can store more readings using SINT
than in any other memory format.) Use the DINT memory format when
making high-resolution measurements (5.5 digits or greater) at the fastest
possible rate on a fixed range.
When using the SINT or DINT memory format, the multimeter applies a
scale factor to the readings. The scale factor is based on the multimeter's
configuration (measurement function, range, A/D converter setup, and
enabled math operations). When recalling readings, the multimeter
calculates the scale factor based on its present configuration. If the
configuration was changed since the readings were stored, a different scale
factor may be used which produces incorrect readings. When recalling
stored readings, it is very important that the multimeter be configured as it
was when the readings were stored. You should not use the SINT or DINT
format for frequency or period measurements; when a realtime or
post-process math operation is enabled (except STAT or PFAIL); or when
autorange is enabled.
•
Single Real (SREAL) or Double Real (DREAL) Unlike the SINT and
DINT formats, readings stored in SREAL or DREAL format are not scaled
and can be used with any measurement function/multimeter configuration.
(Since there is no scale factor, the SREAL and DREAL formats are ideal
when auto ranging and/or a math function is enabled). Use the SREAL
format for measurements with £6.5 digits of resolution. Use the DREAL
format for measurements with >6.5 digits of resolution.
1
16 bytes per reading
2 bytes per reading
4 bytes per reading
4 bytes per reading
8 bytes per reading
Chapter 4 Making Measurements 95