Chapter 2
NI 5450 Overview
©
National Instruments Corporation
2-47
NI PXIe-5450 User Manual
Calculate the amount of memory that a waveform takes up in the onboard
memory with the following two rules.
1.
Each sample in the waveform uses two bytes of memory space. Four
bytes are used when the onboard signal processing block is enabled
and the Data Processing Mode property is set to Complex or the
NIFGEN_ATTR_OSP_DATA_PROCESSING_MODE
is set to
NIFGEN_VAL_OSP_COMPLEX
.
2.
Memory is written to in blocks of 4 bytes.
Calculate the memory size by multiplying the number of samples in the
waveform by two (or four) and then rounding this value up to the nearest
multiple of 128.
Examples
1.
A waveform containing 16 samples occupies 32 bytes in memory. By
rounding up to the nearest multiple of 128, you can determine that the
waveform occupies 128 bytes in memory.
2.
A waveform containing 64 samples occupies 128 bytes in memory. By
rounding up to the nearest multiple of 128, you can determine that the
waveform occupies 128 bytes in memory.
3.
A waveform containing 68 samples occupies 136 bytes in memory. By
rounding up to the nearest multiple of 128, you can determine that the
waveform occupies 256 bytes in memory.
4.
A waveform containing 10,000 samples occupies 20,000 bytes in
memory. By rounding up to the nearest multiple of 128, you can
determine that the waveform occupies 20,096 bytes in memory.
5.
A waveform containing 64 complex samples occupies 256 bytes in
memory. By rounding up to the nearest multiple of 256, you can
determine that the waveform occupies 256 bytes in memory. This
example is only possible with the OSP block enabled.
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