20
Agilent 34950A 64-Bit Digital I/O and Counter Module User’s Guide
Byte Ordering
Byte Ordering
When using buffered memory operations, the width of the data sets how
the memory data is interpreted. Changing the width of the first channel in
a bank invalidates any traces stored or captured.
Output Operations
For output operations (see
page 14
), traces are put into
memory using the
TRACe:DATA:DIGital
command.
For output operations, the data stored in memory is output as follows:
•
BYTE
output - first byte in memory on the first handshake, next byte in
memory on the second handshake, and so on.
•
WORD
output - first and second byte in memory on the first handshake,
next two bytes in memory on the second handshake, and so on.
•
LWORd
output - first four bytes in memory on the first handshake, next
four bytes in memory on the second handshake, and so on.
Note that for
WORD
outputs the first byte in memory is considered the
most significant byte and is output on the upper bits (8 through 15).
For
LWORd
outputs the first byte is output on bits 24 through 31.
You can change the byte order reported using the
FORMat:BORDer
command. This command allows you to swap the most- significant and
least- significant byte ordering for all data transfer operations.
The command is applied globally and cannot be assigned to an individual
slot or channel.
Input Operations
For input operations (see page
page 16
), bytes are read
into memory as follows:
•
BYTE
input - the first byte in memory was read on the first handshake,
the next byte in memory was read on the second handshake, and so on.
•
WORD
input - first and second byte in memory were read on the first
handshake, next two bytes in memory were read on the second
handshake, and so on.
•
LWORd
input - first four bytes in memory were read on the first
handshake, next four bytes in memory were read on the second
handshake, and so on.
Note that for
WORD
inputs the first byte in memory is considered the most
significant byte and was read on the upper bits (8 through 15). For
LWORd
inputs the first byte was read on bits 24 through 31.
