National Instruments NI 5401 Manuel D’Utilisation

Chapter 2

Function Generator Operation

2-4

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Each stage is made up of two instructions: the frequency, which specifies 
the frequency of the waveform to be generated, and the time, which 
specifies the time for which the frequency is to be generated.

You cannot specify the number of iterations for a waveform to be generated.

You can define a staging list for performing frequency hops and sweeps. 
The entire staging list uses the same buffer loaded into the lookup memory. 
All stages differ in the frequency to be generated. 

The minimum time that a frequency should be generated is 2 µs. Therefore, the 

maximum hop rate from frequency to frequency is 500 kHz.

The maximum number of stages that can be stored in the instruction FIFO 
for DDS mode is 512. For more information on the waveform generation 
process, refer to your software documentation.

You use triggering to start and step through a waveform generation. The 
trigger sources and modes of operation are explained in the following 
sections.

Trigger sources are software selectable. By default, the software produces 
the trigger sources. You can also use an external trigger from a pin on the 
digital I/O connector, the RTSI trigger lines on the RTSI bus, or the TTL 
trigger lines on the PXI trigger bus on the backplane. Figure 2-4 shows the 
trigger sources for the NI 5401.