Recalling Readings; Overload Indication; Using Reading Numbers - Agilent Technologies 3458A User Manual

Overload Indication

Recalling Readings

Using Reading Numbers

96 Chapter 4 Making Measurements
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ASCII This memory format can be used for any measurement
function/multimeter configuration. Since ASCII has the greatest. number
of bytes per reading, you should use it only when the output format is
ASCII, measurement speed is not critical, and the number of readings to
be stored is not great.
The MFORMAT command specifies the reading memory format (the
power-on and default format is SREAL). For example, to select the single
integer format, send:
OUTPUT 722; "MFORMAT SINT"
The multimeter indicates an overload condition (input greater than the
present range can measure) by storing the value ± 1E+38 in reading memory
instead of a reading. When overload values are recalled to the display, the
value ± lE+38 is displayed. When overload values are transferred from
reading memory to the GPIB output buffer, they are converted to the overload
numbers for the specified output format. Refer to "Sending Readings Across
the Bus" later in this chapter for more information.
You can recall readings from memory using the reading number or by a
method called "implied read". Regardless of the specified reading memory
format, recalled readings are output in the format specified in the OFORMAT
command (refer to "Sending Readings Across the Bus" later in this chapter
for more information). Before recalling readings, you may want to determine
the number of readings stored. This can be done using the MCOUNT? query
command. The following program returns the total number of stored
readings.
10 OUTPUT 722;"MCOUNT?"
20 ENTER 722;A
30 PRINT A
40 END
The multimeter assigns a number to each reading in reading memory. The
most recent reading is assigned the lowest number (1) and the oldest reading
is assigned the highest number. Reading numbers are always assigned in this
manner regardless of whether the LIFO or FIFO mode is used. The RMEM
command allows you to use the reading number(s) to copy a reading or group
of readings from memory to the output buffer. The RMEM command does
not destroy readings in memory: it merely copies the reading(s) to the output
buffer.
The RMEM command turns reading memory OFF. This means all previously
stored readings remain intact and new readings are not stored. The first
parameter in the RMEM command specifies the beginning reading (first
parameter). The second parameter (count) specifies the number of readings
to be recalled, starting with first. The third parameter (record) specifies the
record from which to recall readings. Records correspond to the number of
readings specified in the NRDGS or SWEEP command. For example, if you
have specified four readings in the NRDGS command, each record in reading
memory contains four readings. The following program specifies 10 readings
per trigger (NRDGS 10) and uses the TARM SGL command to take 8 groups
of 10 readings (multiple trigger arming). This will place a total of 80 readings