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Chapter 2 Function Reference — DIG_Trigger_Config
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National Instruments Corporation 2-193 NI-DAQ FRM for PC Compatibles
stopTrig specifies the source of the stop trigger.
0: None.
1: Hardware trigger.
2: Digital pattern trigger (input group only).
stopPol specifies the polarity of the stop trigger.
0: Active high.
1: Active low.
2: Pattern matched.
3: Pattern not matched.
ptsAfterStopTrig is the number of data points to acquire following the trigger. This
parameter is valid only if stopTrig is not 0. If stopTrig is 2, this number will include the
matching pattern.
Range: 2 through count, where count is the value of the count parameter in the
DIG_Block_* functions.
pattern is the digital pattern to be used as a trigger point. This parameter is used only when
either startTrig or stopTrig is 2.
lineMask selects the individual data lines to be compared when startTrig or stopTrig is 2
or 3 or when you enable change detection, using
DIG_Block_PG_Config. This parameter
allows you to set all the DON’T_CARE bits in the pattern. A 0 means DON’T_CARE, but
a 1 is significant.
Using This Function
If startTrig is 0, a digital block operation begins as soon as you call a DIG_Block_*
function. If startTrig is 1, a digital block operation does not begin until NI-DAQ receives an
external trigger pulse on the group’s ACK (STARTTRIG) pin.
If stopTrig is 0, a digital block operation ends as soon as the operation reaches the end of the
buffer (unless you enable double buffering with the
DIG_DB_Config function). If stopTrig
is 1, a digital block operation continues in a cyclical mode until NI-DAQ receives an external
trigger pulse on the group’s STOPTRIG pin, at which time NI-DAQ acquires an additional
number of data points specified by ptsAfterStopTrig before terminating the operation. The
DIG_Block_Check function rearranges the data into chronological order (from oldest to
newest).
If startTrig or stopTrig is 2 or 3, the board compares incoming data to the specified pattern.
The DIO 6533 contains a single pattern-detection circuit per group. Therefore, you cannot set
both startTrig and stopTrig to 2 or 3. You also cannot set startTrig or stopTrig to 2 or 3
and also configure a pattern-detection message (DAQEvent = 7 or 8) using
Config_DAQ_Event_Message.