|This mode uses an external TTL signal fed into the dedicated trigger
TTL input connector on the card. It checks to see if it 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
and waiting for a trigger. 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 TTL 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 M2i card driver software
|An alternative mode is for detecting if the pulses of an external TTL signal
are SHORTER than a programmed pulsewidth. If this is the case then the card is
triggered and will start to record. For any situation when the pulse
is longer than the programmed pulsewidth, no trigger will be initiated.
|The M2i card driver also provides a GATED SAMPLING function. This gate when
combined with the pulsewidth dictates both the start and stops recording.
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
|The pulsewidth function can can also be set to monitor and act directly
on the analogue signal channels, when combined with window triggering.
Pulsewidth can also be combined in a AND / OR logic arrangement with other sources,
e.g. a software trigger (such as key press), or a signal from the card's
optional BASEXIO TTL inputs.
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 09.01.19