Model 871A User’s Manual MAKING MEASUREMENTS
Bristol Instruments, Inc. 37
Data Semantics
The binary data consists of a wavelength, a relative power, a status word, and a scan
index, in that order, for each buffered measurement. The description of each field is as
follows.
• Wavelength – The wavelength is given in nanometers. It is expressed as a double-
precision (64-bit) floating-point number.
• Power – The power is given as the relative intensity on the detector. It is expressed as
a single-precision (32-bit) floating-point number.
• Status – The status word is a 32-bit-wide bitfield. The meaning of each bit is
described in Appendix E.
• Scan Index – The scan index is a 32-bit, unsigned integer whose value increases by
one with each measurement. The first scan index emitted by the instrument is 0, and
the measurement after scan index 2^32 = 4294967296 will have scan index 0 again.
Unlike the RS-422 communication, there are no escape or start characters to parse while
reading this file.
Downloading Data Buffer
The data buffer is retrieved through the NuView software or over Telnet through USB or
Ethernet SCPI commands in block data format. The data is sent in binary with the
following structure:
#<Digits in byte total><Total bytes in Data><Data><nl>
As an example, if there is 10,000 bytes in the data buffer then the SCPI response would
be:
#510000<data><nl>
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