Keysight Technologies 3458A Guide D'utilisation page 449

Optimizing the Testing Process Through Task Allocation
Math operations
Individually, math operations performed within the 3458A slow the measurement
speed of the 3458A, but many times the combination of the 3458A with the
controller will perform faster together to achieve final answers if the 3458A does
some of the math itself. This is particularly true for pass/fail limit checking where
The computer is alerted only if the test has failed. If statistics are important on the
measurements, then it is a simple matter to let the 3458A assume the task of
computation instead of having to write a program on the controller. The computer
in the 3458A is a very powerful Motorola 68000 with a 8 MHz operating clock;
therefore, many times it will have the same computational power that the
controller has.
Data storage
The memory of the 3458A can be used to store measurements for later transfer to
the controller for up to 10,000 readings (20 kBytes). Optionally, one may use the
Option 001, Expanded Memory and get an additional 65,000 reading (128 kBytes)
storage. The transfer rate into and out of the Reading Memory and the GPIB
transfer rate using direct memory access with an HP 9000 Series 200/300
computer is 100,000 readings per second. The advantage of the memory is that
one may access the data when it is convenient for the controller and not have to
tie the system up waiting for the measurement to finish (a long integration period,
a long settling time, or an average of multiple readings can cause even the fastest
dmm to hold up the system).
Output formats
The 3458A offers five different data formats for both memory and GPIB output:
single integer (SINT), double integer (DINT), IEEE-728 four byte single real
(SREAL), IEEE-728 eight byte double real (DREAL), and ASCII. The fastest format
for data transfer is the single integer. This is a 16 bit integer format so range
information must be known to determine the placement of the decimal point. In
addition, it only has 16 bits; hence, if more than 4 1/2 digits is desired from a
measurement, one of the other formats must be used. The next highest speed
format is double integer. This is a 32 bit integer format so, except for the range
Keysight 3458A User's Guide
Optimizing Throughout and Reading Rate D
449