Chapter 4
Arb Operation
DAQArb 5411 User Manual
4-4
©
National Instruments Corporation
Waveform Size and Resolution
The DAQArb 5411 stores arbitrary waveforms in memory as 16-bit
digital words. Only the 12 most significant bits are sent to the digital
filter and the DAC. The following sections describe the waveform
memory, the sizes available, and minimum buffer size.
Waveform Memory
The DAQArb 5411 uses a waveform memory16 bits wide. The standard
memory size is 2,000,000 samples. This large memory means you can
store very long waveforms on the board itself and obtain reliable
waveform generation even at full speed. You can upgrade to an
8 million-sample waveform memory by installing the optional 16 MB
memory module. See Chapter 2, Installation and Configuration, for
more information on the memory module.
As shown in Figure 4-3, a 2,000,000-sample waveform memory is
organized as eight banks of 256 k by 16-bit memory chips. These eight
banks are then shifted serially to achieve a single data stream of 16-bit
words at 40 MHz.
Figure 4-3.
Waveform Memory Architecture
256 k X 16 bits
(1 M X 16 bits)
2 M Words
(8 M Words)
256 k X 16 bits
(1 M X 16 bits)
256 k X 16 bits
(1 M X 16 bits)
256 k X 16 bits
(1 M X 16 bits)
256 k X 16 bits
(1 M X 16 bits)
256 k X 16 bits
(1 M X 16 bits)
256 k X 16 bits
(1 M X 16 bits)
256 k X 16 bits
(1 M X 16 bits)
Pi Load + Shift Register
16
Clock
Memory
Control Lines
Waveform Data
16
16
16
16
16
16
16
16
