National Instruments NI 6602, Руководство пользователя

Страница: 26 / 60

Chapter 3 Signal Connections
© National Instruments Corporation 3-3 NI 660x User Manual
are t
fltrclk
or shorter. A p u lse with a width between these two ranges may or
may not pass, depending on the phase of the p u lse with respect to the filter
clock timebase.
Table 3-1 s u mmarizes the properties of the different filter settings.
Yo u individ u ally config u re the filter setting for each PFI line. The filters are
u sef u l to maintain signal integrity. They can prevent meas u rement errors
ca u sed by noise, crosstalk, or transmission line effects.
Note The digital filters on the NI 660 x devices are not enabled by defa u lt.
For more information abo u t u sing the digital filters on yo u r device, refer to
the NI-DAQmx Help .
Power-On State
The PFI lines are weakly p u lled down within the NI-TIO ASIC, and the
RTSI lines are weakly p u lled high. Connections for p u lling u p the PFI lines
or for stronger p u ll-down connections m u st be made external to the
NI 660 x . These connections affect the drive strength of the NI 660 x when
the lines p u lled u p or down are u sed as o u tp u ts.
Pin Assignments
Table 3-2 lists the pin assignments for the I/O connector on the NI 660 x .
Note The NI 6601 u ses co u nters <0..3> only.
Table 3-1. Filter Settings
Filter Setting Pulse Width Passed Pulse Width Blocked
5
μ
s 5
μ
s 2.5
μ
s
1
μ
s 1
μ
s 500 ns
500 ns 500 ns 250 ns
100 ns 100 ns 50 ns
Programmable setting
with period of clock = t
fltrclk
2*t
fltrclk
t
fltrclk