Chapter4 HardwareOverview
©NationalInstruments Corporation 4-9 NI5102 User Manual
Note IfScan Clock is externally supplied, you must supply a free-running clock for proper
operation.
On the NI 5102 (ISA, PCMCIA, USB), data transfer takes place after an
acquisitionends, limiting th e scan count to the size of the onboard memory.
On the NI 5102 (PCI, PXI), data can be movedvery quickly from the
digitizer to host memory while an acquisition is in progress. The NI 5102
(PCI,PXI) takes advantage of the NI MITE on the application-specific
integratedcircuit (ASIC) to master the PCI bus and transfer data acquired
on both channels to PC memory in real time without losing data. This
technologylets you acquire more data than 663,000 samples, the size of the
onboardmemory. This property of the PCI bus extends the maximum scan
countto16millionscans.
Figure 4-8 showsthe timin g signals involvedin a posttrigger acquisition.
In this example,the hardware is programmed to acquire 10 posttriggered
scans.
Figure4-8. PosttriggerAcquisition
Table4-4. PossibleNumber of Samples for Posttriggered Scans
Number
of
Channels
NI5 102 (PCI, PXI)
NI 5102 (ISA,
PCMCIA, USB)
Min Max Min Max
One 116,777,088* 1663,000
Two 116,777,088* 1331,500
*Dependent on available memory
StartTrigger
ScanClock
Endof
Acquisition
Input
FirstScan Clock Pulse
=Posttrigger Points