2.7 Trigger Modes
The USBscope50 can use three main types of triggering. These modes are used when the “run” button or the “once14” button has been pressed causing the scope to enter the run state.
2.7.1 Auto Triggering
In this mode the acquisition begins just after the software has set up the scope. The scope will effectively free run, but it will try periodically to trigger from the input waveform. If a trigger is detected the scope will stay in a mode to enable it run as though it is in Normal mode (see below). This means the scope will lock to the waveform. If no trigger is detected the scope will carry in in a Free Run mode. Note that when you adjust the trigger threshold or the timebase, the scope will shorten the time until the next trigger test so that it can lock to the waveform more rapidly as you adjust these settings. If the scope looses lock on the waveform, you will observe a brief delay (1 to 2 seconds) before the Free Run mode is resumed.
In Auto mode, when triggering is detected, the trigger status panel will illuminate red.
14The once button does a single acquisition and so does not perform any trigger test when in Auto mode. Effectively, using the once button in Auto mode is the same as using it in Free mode. In Norm mode, the scope will wait for the trigger event during a “once” acquisition.
Elan Digital Systems Ltd. | 21 | USBscope50 USER’S GUIDE Iss5 |