It is normal for the scope to take several seconds to move from free run to triggered mode when a signal is first applied to the scope input or is changed significantly.
2.7.2 Normal Triggering
In this mode, the acquisition is primed, but will not start until the input waveform meets some criteria. This mode will cause the waveform on the screen to “lock” to an edge and so appear fixed in time. It is useful for observing regular waveforms or for doing a single triggered acquisition. If no suitable waveform is present, the scope will wait indefinitely with no display update in the meantime.
2.7.3 Free Triggering
This mode is a simple Free Run (like Auto Mode) with no attempt to lock to the input waveform. It is good for checking DC levels etc. Note there are no options for edge selection as these have no effect in Free Mode.
Elan Digital Systems Ltd. | 22 | USBscope50 USER’S GUIDE Iss5 |