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Trigger holdoff is an adjustable period of time during which the digitizer cannot trigger. NI high-speed digitizers use trigger holdoff to guarantee a minimum time between two Reference Triggers. This feature is useful if incoming triggers are a known time apart and only a relatively small window of samples adjacent to the trigger are necessary. In this case, setting the holdoff allows you to efficiently allocate the onboard memory, and prevents the device from triggering on sections of the input waveform that are not of interest. Each device uses an onboard counter that is programmed by software to implement this functionality. While the holdoff counter is decrementing, incoming Reference Triggers are ignored. The device arms itself for the next Reference Trigger when the holdoff counter reaches zero. Each device that supports trigger holdoff has a minimum holdoff value, which is listed in the specifications document for each device.
|Note Trigger holdoff is not supported by all digitizers. Some digitizers allow only trigger holdoff or trigger delay at any given time. Refer to Features Supported by Device to find out which digitizers support trigger holdoff.|
The details of how holdoff is implemented on each device varies. Refer to the device-specific help sections for more information on your particular digitizer.