Keithley 2520, Руководство пользователя, Страница: 210 / 329

Model 2520 User’s Manual SCPI Command Reference 14-21
Figure 14-2
IEEE-754 single precision data format (32 data bits)
During binary transfers, never un-talk the Model 2520 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.
NOTE The Model 2520 terminates the binary data string with LF + EOI. If your pro-
gram is set to terminate on CR and/or LF, data transfer may terminate prema-
turely because one or more data bytes has a CR or LF value. To avoid the
problem, set your computer program to terminate on EOI only.
The number of bytes to be transferred can be calculated as follows:
Bytes=2+(Rdgs
×
4) + 1
where 2 is the number of bytes for the header (#0).
Rdgs is the product of the number of selected data elements, arm
count, and trigger count.
4 is the number of bytes for each reading.
is the byte for the terminator.
For example, assume the Model 2520 is configured to perform 10 source
and measure operations and send the 10 current measurements to the
computer using the binary format.
Bytes = 2 + (10 x 4) + 1 = 43
s
# 0
7 0 7 0 7 0 7 0
e f
Header
Byte 1 Byte 2 Byte 3 Byte 4
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 and terminator are sent only once for each READ?