READ?
The
READ?
command is most commonly used with
CONFigure
to:
Place the multimeter in the wait-for-trigger state (executes the
INITiate
command).
Transfer the readings directly to the output buffer when the trigger is received (same
action as
FETCh?
but the readings are not stored in memory).
Subsystem Syntax
READ?
Comments
•
The
READ?
command is slower than the
INITiate
command since readings are
formatted and sent to the output buffer as they are taken. However, the sample
count and trigger count are not limited with
READ?
since memory is not used.
•
This command causes the multimeter to start taking readings as soon as its trigger
requirements are met (this is the same as the
INIT
command).
•
Each reading sent to the output buffer is terminated with a Line Feed (LF). The
HP-IB End-or-Identify (EOI) signal is sent with the last byte transferred. If
multiple readings are returned, the readings are separated by commas and EOI is
sent only with the last byte.
•
The output buffer capacity is 128 bytes. When the buffer fills, the multimeter
remains "busy" until you begin removing readings from the buffer.
•
Readings are placed directly in the output buffer; therefore, mainframe RAM is not
allocated for the readings. You may want to use this mode of operation when
readings need to be taken at a continuous rate.
•
The rate the controller removes the readings need to match the multimeter to keep
from causing an overflow condition.
controller output buffer 128 characters
multimeter
FIFO 512
words
for example, 10
µ
s aperture equals 1 word per reading; all other apertures equals 2
words per reading.
•
Related Commands:
CONFigure
,
FETCh?
,
INITiate
Example
Transferring Readings Directly to Output Buffer
dimension array
!Dimension computer array to store 100
readings.
CONF:VOLT:DC
!Function: DC voltage; stand-alone
multimeter.
SAMP:COUN 100
!Specify 100 readings per trigger
(stand-alone multimeter only).
155 Command Reference
Chapter 5
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