National Instruments NI660 Series, Руководство пользователя

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Chapter 3 Signal Connections
NI 660x User Manual 3-12 ni.com
Yo u can export the Ctr n Gate signal to the I/O connector’s defa u lt PFI inp u t
for each Ctr n Gate. For example, yo u can export the gate signal connected
to co u nter 0 to the PFI 38/CTR 0 GATE pin, even if another PFI is inp u tting
the Ctr0Gate signal. This o u tp u t is set to high-impedance at start u p.
Fig u re 3-6 shows the timing req u irements for the Ctr n Gate signal.
Figure 3-6. Timing Requirements for CtrnGate Signal
Table 3-6 shows the minim u m p u lse width req u ired for the internal signals.
Note For b u ffered meas u rements, the minim u m period req u ired for the Ctr n Gate signal is
determined by how fast the system can transfer data from yo u r device to comp u ter memory.
Counter n Auxiliary Signal
Yo u can select any PFI or RTSI, as well as many other internal signals as
the Co u nter n A u xiliary (Ctr n A u x) signal. M u ch like this Ctr n Gate signal,
the Ctr n A u x signal is config u red in edge-detection or level-detection mode
depending on the application performed by the co u nter. The a u x signal can
perform many different operations incl u ding starting and stopping the
co u nter, generating interr u pts, and saving the co u nter contents. Yo u can
also u se this signal to control the co u nting direction in edge-co u nting
applications.
Table 3-6. Minimum Pulse Width for Ctr n Gate Internal Signals
Parameter Minimum
Minimum with
RTSI Connector Description
Tgatepw 5 ns 5 ns Ctr n Gate minim u m p u lse width
Ctr n Gate
Tgatepw
Tgatepw
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