Keithley 2002, User Manual

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IEEE-488 Reference
3-80
REAL,32 or SREal will select the binary IEEE754 single precision data format. Figure 3-19
shows the normal byte order format for each data element. For example, if three valid elements
are specified, the data string for each reading conversion is made up of three 32-bit data blocks.
Note that the data string for each reading conversion is preceded by a 2-byte header that is the
binary equivalent of an ASCII # sign and 0.
REAL,64 or DREal selects the binary IEEE754 double precision data format and is shown in
Figure 3-20 (normal byte order shown). This format is similar to the single precision format
except that it is 64 bits long.
Figure 3-19
IEEE754 single precision data format (32 data bits)
Byte 1
7 0
Header
# 0
Byte 2
7 0
Byte 3
7 0
Byte 4
7 0
s e f
s = sign bit (0 = positive, 1 = negative)
e = exponent bits (8)
f = fraction bits (23)
Normal byte order shown. For swapped byte order,
bytes sent in reverse order: Header, Byte 4, Byte 3,
Byte 2, Byte 1.
The Header is only sent once for each measurement conversion.