NI High-Speed Digitizers Help (NI-SCOPE)

Edition Date: January 2017

Part Number: 370592AB-01

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C Function Prototype

ViStatus niScope_ConfigureTriggerHysteresis (ViSession vi, ViConstString triggerSource, ViReal64 level, ViReal64 hysteresis, ViInt32 slope, ViInt32 triggerCoupling, ViReal64 holdoff, ViReal64 delay);


Configures common properties for analog hysteresis triggering. This kind of trigger specifies an additional value, specified in the hysteresis parameter, that a signal must pass through before a trigger can occur. This additional value acts as a kind of buffer zone that keeps noise from triggering an acquisition.

When you initiate an acquisition, the digitizer waits for the start trigger, which is configured through the NISCOPE_ATTR_ACQ_ARM_SOURCE (Start Trigger Source). The default is immediate. Upon receiving the start trigger the digitizer begins sampling pretrigger points. After the digitizer finishes sampling pretrigger points, the digitizer waits for a reference (stop) trigger that you specify with a function such as this one. Upon receiving the reference trigger the digitizer finishes the acquisition after completing posttrigger sampling. With each Configure Trigger function, you specify configuration parameters such as the trigger source and the amount of trigger delay.

Note  Some features are not supported by all digitizers. Refer to Features Supported by Device for more information.

Related topics:


Name Type Description
vi ViSession The instrument handle you obtain from niScope_init that identifies a particular instrument session.
triggerSource ViConstString Specifies the trigger source. Refer to NISCOPE_ATTR_TRIGGER_SOURCE for defined values.
level ViReal64 The voltage threshold for the trigger. Refer to NISCOPE_ATTR_TRIGGER_LEVEL for more information.
hysteresis ViReal64 The size of the hysteresis window on either side of the level in volts; the digitizer triggers when the trigger signal passes through the hysteresis value you specify with this parameter, has the slope you specify with slope, and passes through the level. Refer to NISCOPE_ATTR_TRIGGER_HYSTERESIS for defined values.
slope ViInt32 Specifies whether you want a rising edge or a falling edge to trigger the digitizer. Refer to NISCOPE_ATTR_TRIGGER_SLOPE for more information.
triggerCoupling ViInt32 Applies coupling and filtering options to the trigger signal. Refer to NISCOPE_ATTR_TRIGGER_COUPLING for more information.
holdoff ViReal64 The length of time the digitizer waits after detecting a trigger before enabling NI-SCOPE to detect another trigger. Refer to NISCOPE_ATTR_TRIGGER_HOLDOFF for more information.
delay ViReal64 How long the digitizer waits after receiving the trigger to start acquiring data. Refer to NISCOPE_ATTR_TRIGGER_DELAY_TIME for more information.

Return Value

Name Type Description
Status ViStatus Reports the status of this operation. To obtain a text description of the status code, call niScope_GetErrorMessage. To obtain additional information concerning the error condition, use niScope_GetError and niScope_ClearError. The general meaning of the status code is as follows:

Value Meaning
0 Success
Positive Values Warnings
Negative Values Errors


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