Power-On State - National Instruments NI 6608 User Manual

Filter Setting
5 μs
1 μs
500 ns
100 ns
Programmable setting
with period of clock = t
Note The digital filters on the NI 660x devices are not enabled by default.

Power-On State

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In addition to these hard-wired filter clocks, you can use any PFI, RTSI, or
internal signal as the source for the filter clock timebase. Use signals with
a duty cycle as close to 50 percent as possible.
If the period of the filter clock timebase is t
pass pulse widths that are 2*t
are t or shorter. A pulse with a width between these two ranges may or
fltrclk
may not pass, depending on the phase of the pulse with respect to the filter
clock timebase.
Table 3-1 summarizes the properties of the different filter settings.
Table 3-1. Filter Settings
Pulse Width Passed
5 μs
1 μs
500 ns
100 ns
2*t
fltrclk
fltrclk
You individually configure the filter setting for each PFI line. The filters are
useful to maintain signal integrity. They can prevent measurement errors
caused by noise, crosstalk, or transmission line effects.
For more information about using the digital filters on your device, refer to
Digital Filtering for Counters in the NI-DAQmx Help.
The PFI lines are weakly pulled down within the NI-TIO ASIC, and the
RTSI lines are weakly pulled high. Connections for pulling up the PFI lines
or for stronger pull-down connections must be made external to the
NI 660x. These connections affect the drive strength of the NI 660x when
the lines pulled up or down are used as outputs.
fltrclk
or longer and to block pulse widths that
fltrclk
2.5 μs
500 ns
250 ns
50 ns
t
fltrclk
3-3
Chapter 3 Signal Connections
, this filter guarantees to
Pulse Width Blocked
NI 660x User Manual