Keithley 2302 Instruction Manual page 196

11-6 DISPlay, FORMat, and SYSTem
DREal selects the binary IEEE-754 double precision data format and is shown in
Figure 11-2
except that it is 64 bits long.
Figure 11-2
IEEE-754 double precision data format
Header Byte 1
# 0
7
s
Bytes 3, 4, 5, and 6 not shown.
s = sign bit (0 = positive, 1 = negative)
e = exponent bits (11)
f = fraction bits (52)
During binary transfers, never un-talk the power supply until after the data is read (input) to
the computer. Also, to avoid erratic operation, the readings of the data string (and terminator)
should be acquired in one piece. The header (#0) can be read separately before the rest of the
string.
The number of bytes to be transferred can be calculated as follows:
Bytes = 2 + (Rdgs × 4) + 1 for SREAL
Bytes = 2 + (Rdgs × 8) + 1 for DREAL
where: 2 is the number of bytes for the header (#0).
For example, assume that the power supply is configured to trigger 10 voltage readings and
send the 10 voltage measurements to the computer using the binary format.
Bytes = 2 + (10 × 4) + 1 = 43 for SREAL
Bytes = 2 + (10 × 8) + 1 = 83 for DREAL
FORMat:BORDer <name>
Parameters
This command is used to control the byte order for the IEEE-754 binary formats. For normal
byte order, the data format for each element is sent as follows:
Byte 1
Byte 1
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
TestEquipmentDepot.com
(normal byte order shown). This format is similar to the single precision format
Byte 2 Byte 7
0 7 0 7
e
Normal byte order shown. For swapped byte order,
bytes sent in reverse order: Header, Byte 8,
Byte 7 .... Byte 1.
The Header is only sent once for each measurement conversion.
Rdgs is the number of readings to be transferred.
4 or 8 is the number of bytes for each reading.
1 is the byte for the terminator.
<name> = NORMal
SWAPped
Byte 2Byte 3Byte 4
Byte 2• • • Byte 8
Byte 8
0 7 0
f
Specify binary byte order
Normal byte order for binary formats
Reverse byte order for binary formats
(Single precision)
(Double precision)