|Any of the multi-purpose I/O lines on the M2p card can be fed by an
external LVTTL trigger signal pulse. The card can be programmed to check
if it duration is LONGER than a programmed pulsewidth. The card will then
trigger and record. The next trigger event will only be detected if the current recording
has finished and the card has re-armed. For any situation when the pulse is shorter than
the programmed pulsewidth, no trigger will be detected. This has the added benefit
that a noisy LVTTL signal would not initiate false triggers. The diagram shows
high-going pulses, but another mode allows low-going pulses to be utilised.
For which ever case a programmed pulsewidth is simply made in the appropriate
code register of the M2p card driver software. Digital I/O and waveform generator cards
may control their replay of signals using a similar method.
|An alternative mode is for detecting if the pulses are SHORTER than a programmed
pulsewidth. If this is the case then the card is triggered and will start to record or replay.
For any situation when the pulse is longer than the programmed pulsewidth, no trigger will be initiated.
|The M2p card driver also provides a GATED SAMPLING function. This gate when
combined with the pulsewidth dictates both the start and stop of recording (or replay).
In the diagram gate period starts when the programmed pulsewidth has been exceeded.
The card is now triggered and sampling until the next falling edge. This also
works for low going pulses where the sampling will end on a rising edge. Ths process
can be repeated for a series of pulses and gates.
|Pulsewidth can also be combined in a AND / OR logic arrangement with other sources,
e.g. a software trigger (such as key press). The above is just a summary of the pulsewidth features.
Full details can be found in the user manual.
Images courtesy of Spectrum GmbH
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Last modified by DataQuest Solutions Ltd 05.05.21