What Are the Different Output Modes and Maximum Signal Output Frequencies for the NI 5411?
Hardware: Multifunction DAQ (MIO)
Problem: What are the different output modes and maximum output signal frequencies for the NI 5411?
Solution: There are two output modes for the NI 5411: Arb Mode and Direct Digital Synthesis Mode (DDS Mode)
Arb Mode
- Mainly used for arbitrary waveform generation
- Has a huge FIFO buffer of 2 million samples. Each sample is 16-bit wide. The FIFO can be upgraded to 8 million samples externally by adding optional 16 MB memory.
- Waveform Linking and Looping: You can load buffers of different types of waveforms within the 2 million samples space and output these buffers in any predetermined order.
For example:
Buffer 1: 1 cycle of a sine wave (made of 256 samples)
Buffer 2: 2 cycles of a square wave (made of 512 samples)
Buffer 3: 1 cycle of a triangular wave (made of 512 samples)
Now, you can create something called a "WAVEFORM STAGING LIST" and determine the order and the number of times different buffers will output:
For example:
STAGE 1: 2 loops of Buffer 2 ( which would be 4 cycles of square waves) +
STAGE 2: 4 loops of Buffer 3 (4 cycles of triangular waves) +
STAGE 3: etc., for up to 2 million samples
NOTE 1: Each buffer should be at least 256 samples and should be a multiple of 8
NOTE 2: NI 5411 supports up to 290 different stages
- The maximum update rate (this is not the output waveform frequency, but it is the update rate of the board) is 40 MHz and the board has a 16-bit divide down counter, so the minimum rate is 610.35 Hz:
MAXIMUM UPDATE FREQUENCY 40 MHz
MINIMUM UPDATE FREQUENCY 610.35 Hz
- Use VirtualBench-Arb to work in this mode if you are using VirtualBench.
Direct Digital Synthesis Mode (DDS Mode)
- Use this mode for outputting repetitive signals. You store one buffer of a square, sine, triangular or any arbitrary waveform and loop it many times to produce the repetitive signal.
- You can load one buffer of the waveform you want to output in "Lookup memory" which allows a maximum of 16,384 samples (each sample is a 16-bit number). You should be able to set the maximum update frequency at 40 MHz.
- You can output sine waves of 16 MHz reliably. This is the frequency of the output waveform, not the update frequency; the update frequency should be set to 40 MHz for best resolution.
Related Links: Product Manuals: NI Signal Generators Help
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Report Date: 01/04/1999
Last Updated: 11/19/2008
Document ID: 1H3FIBX4
