Chapter4 ConnectingSignals
NI6013/6014 User Man ual 4-22 ni.com
Pretriggereddata acquisition allows you to view data that is acquired before
the trigger of interest in addition to data acquired after the trigger.
Figure4 -12 showsa typical pretriggered DAQ sequence. The description
foreach signal shown in these figures is included later in this chapter.
Figure4-12. TypicalPretriggered Acquisition
TRIG1 Signal
Any PFIpin can externally input the TRIG1 signal, which is available as
an output on the PFI0/TRIG1 pin.
Refert o Figures 4-11 and 4-12 for the relationship of TRIG1 to the DAQ
sequence.
As ani nput, TRIG1 is configuredin the edge-detection m ode. Youcan
select anyPFI pin as the so urce for TRIG1 and configure the polarity
selectionfor either rising or falling edge. The selected edge of TRIG1starts
the DAQsequence for both posttriggered and pretriggered acquisitions.
Asan output, TRIG1 reflects the action that initiates a DAQ sequence, even
ifthe acquisition is being externally triggered by another PFI. The output is
anactive high pulse with a pulse width of 50 to 100 ns. This o utput is set to
high-impedance at startup.
n/a
01231 0222
TRIG1
TRIG2
STARTSCAN
CONVERT*
ScanCounter