National Instruments NI 5911 User Manual

Also see for NI 5911: Getting started guide

Contents

National Instruments NI 5911 User Manual Manual pdf 22 page image

Chapter 2 Hardware Overview© National Instruments Corporation 2-11 NI 5911 User ManualMultiple-Record AcquisitionsAfter the trigger has been received and the posttrigger samples have beenstored, the NI 5911 can be configured to begin another acquisition that isstored in another onboard memory record. This is a multiple-recordacquisition. To perform multiple-record acquisitions, configure theNI 5911 to the number of records you want to acquire before starting theacquisition. The NI 5911 acquires an additional record each time a triggeris accepted until all the requested records are stored in memory. You mayacquire up to 1024 records if your NI 5911 is equipped with 4 MB ofonboard memory, or 4096 records with 16 MB. Software intervention afterthe initial setup is not required.Multiple-record acquisitions can quickly acquire numerous triggeredwaveforms because they allow hardware rearming of the digitizer beforethe data is fetched. Therefore the dead time, or the time when the digitizeris not ready for a trigger, is extremely small.For more information on multiple-record acquisitions and dead time, seethe Making a Multiple-Record Acquisition section in Chapter 5, Tasks andExamples, of your NI-SCOPE Software User Manual.RTSI Bus and Clock PFIThe RTSI bus allows NI digitizers to synchronize timing and triggering onmultiple devices. The RTSI bus has seven bidirectional trigger lines andone bidirectional clock signal.You can program any of the seven trigger lines to provide or accept asynchronous trigger signal. You can also use any of the RTSI trigger linesto provide a synchronization pulse from a master device if you aresynchronizing multiple NI 5911s.You can use the RTSI bus clock line to provide or accept a 10 MHzreference clock to synchronize multiple NI 5911 devices.PFI LinesThe NI 5911 has two digital lines that can accept a trigger, accept orgenerate a reference clock, or output a 1 kHz square wave. The function ofeach PFI line is independent. However, only one trigger source can beaccepted during acquisition.