Detects a trigger point in a waveform. You can detect the trigger point in terms of index or relative time. The trigger point is specified in terms of threshold level, hysteresis, and slope. You can use this polymorphic VI to perform trigger detection on single channel or multichannel data. The data type you wire to the signal in input determines the polymorphic instance to use.
![]() | Note Do not use the single-channel version of this VI for continuous multiple-channel processing. |
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Reset specifies if the history (or internal state) of the VI has to be reset. The default value is FALSE. The internal state contains the final data value in the input signal. The VI uses this as the initial value the next time the VI is called. | ||||||
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signal in contains the signal in which to detect a trigger. | ||||||
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level contains the threshold level value for the channel.
The low and high threshold values are computed as:
high threshold = level + h/2.0 low threshold = level - h/2.0 where h is the hysteresis value for each channel contained in hysteresis. |
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hysteresis contains the hysteresis for the channel.
The low and high threshold values are computed as:
high threshold = l + hysteresis/2.0 low threshold = l - hysteresis/2.0 where l is the level for each channel contained in level. |
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Mode determines whether trigger is detected in terms of Index or Relative Time. Select Index to detect trigger point in terms of an array index. Select Relative Time to detect trigger point in terms of relative time, where relative time = start time + (array index*time increment). | ||||||
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error in describes error conditions that occur before this VI or function runs.
The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. This VI or function runs normally only if no error occurs before this VI or function runs. If an error occurs while this VI or function runs, it runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node.
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slope contains the slope information for the channel. Rising Edge indicates that the VI detects a trigger on the rising edge (positive slope). Falling Edge indicates that the VI detects a trigger on the falling edge (negative slope). A rising edge (positive slope) trigger is detected if there is a low state to a high state transition. A falling edge (negative slope) trigger is detected if there is a high state to a low state transition. | ||||||
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trigger contains the index at which the trigger is detected in terms of Index or Relative Time, depending on Mode. | ||||||
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trigger detected? indicates if a trigger is detected. | ||||||
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error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, it describes the error status that this VI or function produces.
Right-click the error out indicator on the front panel and select Explain Error from the shortcut menu for more information about the error.
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Reset specifies if the history (or internal state) of the VI has to be reset. The default value is FALSE. The internal state contains the final data value in the input signal. The VI uses this as the initial value the next time the VI is called. | ||||||
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signal in contains the signals in which to detect a trigger. | ||||||
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level contains the threshold level value for all channels.
The low and high threshold values are computed as:
high threshold = level + h/2.0 low threshold = level - h/2.0 where h is the hysteresis value for each channel contained in the input hysteresis. |
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hysteresis contains the hysteresis for all channels.
The low and high threshold values are computed as:
high threshold = l + hysteresis/2.0 low threshold = l - hysteresis/2.0 where l is the level for each channel contained in the input level. |
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Mode determines whether trigger is detected in terms of Index or Relative Time. Select Index to detect trigger point in terms of an array index. Select Relative Time to detect trigger point in terms of relative time, where relative time = start time + (array index*time increment). | ||||||
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error in describes error conditions that occur before this VI or function runs.
The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. This VI or function runs normally only if no error occurs before this VI or function runs. If an error occurs while this VI or function runs, it runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node.
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slope contains the slope information for all channels. Rising Edge indicates that the VI detects a trigger on the rising edge (positive slope). Falling Edge indicates that the VI detects a trigger on the falling edge (negative slope). A rising edge (positive slope) trigger is detected if there is a low state to a high state transition. A falling edge (negative slope) trigger is detected if there is a high state to a low state transition. | ||||||
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trigger contains the value at which the trigger is detected for each channel in terms of Index or Relative Time, depending on Mode. | ||||||
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trigger detected? indicates if a trigger is detected for each channel. | ||||||
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error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, it describes the error status that this VI or function produces.
Right-click the error out indicator on the front panel and select Explain Error from the shortcut menu for more information about the error.
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This VI can perform single-channel measurements in both one-shot mode (single call) and continuous mode (multiple calls with history). It can perform multichannel measurements only in one-shot mode. If you want to make multiple-channel measurements in continuous mode, you must either use the multichannel version of this VI or use one instance of this VI per channel.
The single-channel version of this VI is primarily intended for continuous processing of a single channel. Generalizing this behavior to the multichannel case, typically by using this single-channel VI in a for loop to continuously process multiple channels by indexing an array of waveforms, is a misuse of this VI.
The single-channel version of this VI maintains internal state information for a single channel only. Calling this VI to process another channel without clearing the history, using reset or restart averaging, results in an unexpected behavior of this VI because the internal state information is passed from one channel to another.