Spectrum M2p.59 Series, Руководство по оборудованию, Страница: 102 / 190

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Trigger holdoff Trigger modes and appendant registers
The example shows, how to use the trigger delay command:
Using the delay trigger does not affect the ratio between pre trigger and post trigger recorded number of samples, but only shifts
the trigger event itself. For changing these values, please take a look in the relating chapter about „Acquisition Modes“.
Trigger holdoff
All the cards of the Spectrum M2p series allow the user to program a trigger holdoff time when using one of the segmented acquisition or
generation modes, such as Multiple Recording/Multiple Replay, ABA Mode (analog acquisition cards only) or Gated Sampling/Gated Re -
play. This can be useful when observing and analyzing certain signals that are packeted or bursty in nature.
Using a trigger holdoff will result in an artificially inserted dead-time after each posttrigger area, in which the trigger engine will reject all
detected trigger events. The holdoff value is programmed in samples and the resulting holdoff time will therefore be [Programmed Delay] /
[Sampling Rate].
The following table shows the related register and the possible values. A value of 0 disables the trigger holdoff.
The example shows, how to use the trigger holdoff command:
Main analog external trigger (Ext0)
The M2p series has one primary external trigger input consisting of
an input stage with programmable either 5 kOhm or 50 Ohm input
termination and one comparator that can be programmed in the
range of ±5000 mV. Using a comparators offers a wide range of dif -
ferent logic levels for the available trigger modes that are support like
edge, level.
The external analog trigger can be easily combined with channel trig -
ger or with the additional logic triggersvia the multi-purpose I/O
lines, when being programmed as an additional external trigger in -
put. The programming of the masks is shown in the chapters above.
spcm_dwSetParam_i64 (hDrv, SPC_TRIG_DELAY, 2000); // A detected trigger event will be
// delayed for 2000 sample clocks.
Table 62: Spectrum API: trigger holdoff related registers and settings for these
Register Value Direction Description
SPC_TRIG_AVAILHOLDOFF 40802 read Contains the maximum available holdoff as a decimal integer value.
SPC_TRIG_HOLDOFF 40811 read/write Defines the trigger holdoff for the card’s trigger engine for segmented modes (Multi, ABA, Gate).
0 No additional holdoff will be added.
1…[4G -1] in steps of 1 (16 bit cards) Defines the trigger holdoff in number of sample clocks. The trigger holdoff can be programmed up to
(4 GSamples - 1) = 4294967295. The stepsize is 1 samples for 16 bit cards.
spcm_dwSetParam_i64 (hDrv, SPC_TRIG_HOLDOFF, 2000); // A trigger holdoff is set to 2000
Image 61: trigger engine overview and external trigger