Advanced Trigger Modes and Frequency Lists for NI Function Generators
Primary Software: Driver Software>>NI-FGEN
Primary Software Version: 2.4
Primary Software Fixed Version: N/A
Secondary Software: N/A
Problem: What are the various trigger modes that will allow me to output a sequence of waveforms.
Solution: There are four main modes you can use to trigger waveforms from a list. When you make a frequency list, you need to choose a sequence of waveforms and the length of each sequence.
Single Trigger
Single trigger mode is the simplest of all triggering modes because with this mode, a trigger is used only once during the generation period. A start trigger is typically used to begin the generation of the waveform. The signal generator will output a DC value of 0V while waiting to receive the start trigger. Once this trigger condition is met, the signal generator will begin the generation of the waveform or sequence of waveforms. Once the last waveform in the sequence has been generated, the signal generator will continue to drive the last sample value.
Continuous Trigger
In continuous trigger mode, the entire sequence of waveform segments is continuously generated. The signal generator will generate a DC 0V output once the generation session occurs but before the trigger is received. Once the trigger is received, the signal generator will begin outputting the waveform and will continue to the next waveform in the sequence. Once all the waveforms in the sequence are generated the signal generator will loop back to the first waveform and repeat the entire sequence. It will continue to generate the sequence of waveforms until the generation session is stopped.
Stepped Triggering
In stepped trigger mode, a trigger is used to step through each waveform series in a sequence list. The list defines the number of times that a given waveform will be looped before moving on to the next waveform. When the first trigger is received, the first waveform will loop as many times as has been configured for that particular segment. After the waveform has been looped for the appropriate number of iterations, the last sample of the waveform repeats continuously until the next trigger is received. When the next trigger is received, the second waveform will be generated for the configured number of iterations. This process repeats until the last of the configured waveforms has been generated. At this point, a trigger condition is required to start the generation sequence again.
Burst Triggering
Burst trigger mode is similar to stepped trigger mode except that each waveform in the sequence repeats continuously between each received trigger. In this mode, the signal generator will begin generation of a waveform when a trigger is received. In addition, it will continue looping to generate that waveform until a subsequent trigger is received. Only then will it advanced to the next waveform.
Most boards do support frequency lists, however, some like the NI 5404 do not. You can find the list of features for each board in the NI Signal Generators Help file or manual.
Related Links: Product Manuals: NI Signal Generators Help (NI 5401/5402/5404/5406/5411/5412/5421/5422/5431/5441/5442) (July 2007) Knowledge Base 3N6FFJBC: How to Step Through Output Waveforms Using NI-FGEN
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Report Date: 10/24/2006
Last Updated: 11/02/2007
Document ID: 42NJ8ATT
