DISPlay, FORMat, and SYSTem 11-5
Command notes (SCPI commands — data format)
FORMat[:DATA] <type> Select data format
Parameters <type> = ASCii ASCII format
SREal IEEE754 single precision format
DREal IEEE754 double precision format
This command is used to select the data format for transf
erring readings over the bus. The
reading(s) that is sent depends on the presently selected function (voltage, current, pulse-current,
DVM or long integration). See the :FUNCtion command (SENSe subsystem in Section 2) and
“Signal Oriented Measurement Commands” (Section 10) for more information.
NOTE Re
gardless of which data format for output strings is selected, the power supply will
only respond to input commands using the ASCII format.
ASCII format
The ASCII data format is in a direct readable form for the operator. Most Basic languages
easily con
vert ASCII mantissa and exponent to other formats. However, some speed is
compromised to accommodate the conversion. The following shows the ASCII format for a
reading of 10.058 volts.
+1.00580000 E+01
IEEE754 formats
SREal will select the binary IEEE-754 single precision data format. Figure 11
-1 shows the
normal byte order format for each data element (voltage, current, etc.).
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. Not shown in Figure 11-1 is a byte for the terminator that is attached to the
end of each data string.
Byte 1
70
Header
# 0
Byte 2
70
Byte 3
70
Byte 4
70
se 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.
Figure 11-1
IEEE-754 single precision data format
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