User`s manual

Using Indefinite Length Arbitrary Blocks to Transfer Data
The AFG can receive DAC codes as Indefinite Length Arbitrary Block Data
using either the Signed or Unsigned number format. This is a much faster
method to transfer data than using a comma (“,”) separated list that was
used in “Using Signed Data to Generate Waveforms” on page 225 and
“Using Unsigned Data to Generate Waveforms” on page 229. (The speed is
about the same as the method used in “Using Definite Length Arbitrary
Blocks to Transfer Data” on page 231.)
Indefinite Length
Block Data Format
A typical data block using the indefinite length format consists of:
where:
• “#” – Shows that the data to be sent is in an arbitrary block format.
• “0” – Shows that the format is an indefinite length arbitrary block
format; the “
0” number must be sent since a different number shows
the definite length arbitrary block format.
• “<8-bit data bytes>” – Is the data (i.e., DAC codes) sent to the AFG.
• “LF^END” – Means line feed (LF) sent with END (EOI) asserted. It
indicates to the AFG that the end of data has been reached.
Data Byte Size The DAC codes are transferred to the AFG as 16-bit integer values that meet
the coding set by the IEEE 488.2 standard. Since IEEE 488.2 requires an 8-bit
code, the 16-bit integer must be sent as 2 8-bit values for each 16-bit integer.
For example, to send a waveform segment consisting of 1000 DAC codes
(1000 points), the actual number of “digits” and “8-bit data bytes” equals:
1000 * 2 = 2000
# 0 <8-bit data bytes> LF^END
Start of Data Block End of Line
A "0" Value Data Bytes
Chapter 7 High Speed Operation 235