VTI Instruments EMX-4016B, User Manual

Page: 40 / 118

VTI Instruments Corp.
APPENDIX B 40
Trigger
Offset
Trigger Delay < 0
Trigger
First data point
Sample
Interval
InitialX < 0
Waveform Record
Pre-Trigger
Samples
Re-arm Time
Trigger Holdoff
Figure 4-3: Negative Trigger Delay
The TriggerCount property defines how many times the trigger events are accepted and data blocks
are acquired. After “
TriggerCount
” triggers are processed, the measurement waits for the next
arming condition or finishes. The HoldOff time specifies the minimum amount of time the
measurement has to wait before it can be triggered again once a trigger is detected. Any trigger
events that occurred during the
HoldOff time are ignored. When the specified Holdoff time is shorter
than one data record time length, the two successive data records may be overlapped.
Waveform Record
Waveform Record
Waveform Record
Trigger Holdoff
Trigger
Trigger Trigger
Overlap
Overlap
Figure 4-4: Overlapped Data Acquisition
Alarm
The Alarm is a mechanism that generates events at fixed time interval. The Alarm starts at the time
specified by
TimeSeconds and TimeFraction and repeats for RepeatCount times. The Period
property defines the interval between the two successive alarm events. The Alarm can be used as an
arm or a trigger event source. The Alarm is currently supported by EMX-2500 and Platform driver.