Chapter2 HardwareOverview
©NationalInstruments Corporation 2-11 NI5911 User Manual
Multiple-Record Acquisitions
Afterthe trigger has been received and the posttrigger samples have been
stored,t heN I 5911 can be configured to begin another acquisition that is
stored in another onboard memory record. This is a multiple-record
acquisition.To perform multiple-record acquisitions, configure the
NI 5911 to the number of records you want to acquire before starting the
acquisition.The NI 5911acquires an additional record each timea trigger
is accepteduntil all the requestedrecords are stored in memory. You may
acquire up to 1024 records if your NI 5911 is equipped with 4 MB of
onboardmemory, or 4096 records with 16 MB. Software intervention after
the initial setup is not required.
Multiple-record acquisitions can quickly acquire numerous triggered
waveformsbecause they allow hardware rearming of the digitizer before
thedata is fetched. Therefore the dead time, or the time when the digitizer
is not ready fora trigger, is extremely small.
Formore information on multip le-recordacq uisitions and dead time, see
theMaking a Multiple-Reco rdAcqu isition section in Chapter5, Tasks and
Examples, of your NI-SCOPE Software User Manual.
RTSI Bus and Clock PFI
TheRTSI bus allows NI digiti zers to synchronize timing and triggering on
multiple devices. The RTSI bus has seven bidirectional trigger lines and
one bidirectional clock signal.
Youcan program any of the seven trigger lines to provide or accept a
synchronous trigger signal. Youcan also use any of the RTSI trigger lines
to providea synchronization pulse fro ma master d eviceif you are
synchronizing multiple NI 5911s.
Youcan use the RTSI bus clock line to provide or accept a 10 MHz
reference clock to synchronize multiple NI 5911 devices.

PFI Lines

The NI 5911 hastwo digital lines that can accept a trigger, accept or
generatea reference clock, or output a 1 kH z square wave. The function of
each PFIline is independent. However, only one trigger source can be
accepted duringacquisition.