Bristol 871A - Page 46

Model 871A User’s Manual REMOTE COMMUNICATIONS
Bristol Instruments, Inc. 46
*SAV
Description
The *SAV command saves instrument settings.
*STB?
Description
The *STB (status byte) query returns the current value of the
instrument’s status byte.
Query Response
Returns an integer that is the sum of all the bit values for those bits
that are set. See the instrument Status Byte table.
Instrument Status Byte
BIT
BIT VALUE
CONDITION
5
32
A bit is set in the questionable register (see STATus subsystem)
3
8
Errors are in the error queue (see SYSTem subsystem)
2
4
A bit is set in the event status register
Measurement Instructions
The measurement instructions are used to return a reading to the computer. The three
basic measurement instructions are MEASure, READ, and FETCh. The functions for
these instructions are POWer, ENVironment, FREQuency, WAVelength, WNUMber, and
ALL. The ALL function will return the scan index, instrument status, wavelength
measurement, and power measurement.
The :FETCh command will return a reading of the instrument’s current measurement. If:
FETCh queries are made faster than the instrument’s update rate, it is possible to get the
same reading twice. Duplicate readings are indicated by a bit in the questionable status
register.
The :READ command will return the instrument’s next measurement. The: MEASure
command will return the following measurement. The :MEASure and :READ commands
guarantee that each reading returned is a new one. To get multiple measurement types
from an update (i.e., WAVelength, POWer, etc.), use the :ALL query. Using separate
consecutive :WAVEelength and :POWer queries does not guarantee that they will be
from the same measurement.
The :MEASure command can be considered a macro that executes multiple SCPI
commands and is equivalent to:
:ABORt
:INITiate
:FETCh[ : <function> ]?