User`s manual

Using the VXIbus Backplane
You can use the VXIbus backplane to download or transfer segment and
sequence data to the AFG, and to set the phase modulation angle.
Downloading
Segment Data
There are two ways to use the VXIbus backplane to download the data:
– downloading the list into memory to be executed later
– downloading directly to the DAC for immediate execution
Downloading
Segment Data into
Memory
Download a Combined Segment List and a Combined Sequence List into
memory using the requirements in this section.
Combined Waveform
Segment List Format
Figure 7-4 shows a single 16-bit integer used to download a Combined
Waveform Segment List. Bits 3 through 15 are the DAC codes for the
waveform voltage values, bit 1 is the marker bit, and bit 0 the last point.
• Store the list either as Signed or Unsigned Combined Segment Lists
into memory. Use either Definite Length or Indefinite Length
Arbitrary Block Data to store the data. The list uses a 16-bit word
for each point of the waveform segment.
• Download the segment data directly into the AFG’s High Speed Data
Register. The data must go to the register address with a 38 decimal
(26 hex) offset in the AFG’s A24 address space.
• Be sure to set the last point bit (bit 0) in the list. This indicates to the
AFG that all the segment data has been transferred. Set the bit at the
third-to-last point of the waveform segments (the actual last point = -3).
For example, for a Combined list with a size of 2048, set the bit at
point number 2048 - 3 = 2045.
Figure 7-4. Combined List Format for Downloading
Chapter 7 High Speed Operation 259