Bristol 671 - Measurement Instructions

Model 671 User’s Manual REMOTE COMMUNICATIONS
Bristol Instruments, Inc. 36
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> ]?
{ :MEASure | :READ | :FETCh } { :POWer | :ENVironment | :FREQuency | :WAVelength |
:WNUMber | :ALL }?
Description
Queries a reading of the given type from the measurement subsystem.
Query Response
See below.
Examples
See below.