National Instruments 636 Series User Manual

© National Instruments | 8-5
X Series User Manual
Assume that an input terminal has been low for a long time. The input terminal then changes
from low to high, but glitches several times. When the filter clock has sampled the signal high
on N consecutive edges, the low to high transition is propagated to the rest of the circuit. The
value of N depends on the filter setting; refer to Table 8-1.
The filter setting for each input can be configured independently. On power up, the filters are
disabled. Figure 8-3 shows an example of a low to high transition on an input that has a custom
filter set to N = 5.
Figure 8-3. Filter Example
Enabling filters introduces jitter on the input signal. The maximum jitter is one period of the
timebase.
When a RTSI input is routed directly to PFI, the X Series device does not use the filtered version
of the input signal.
Table 8-1. Filters
Filter Setting Filter Clock
N (Filter
Clocks
Needed to
Pass Signal)
Pulse Width
Guaranteed
to Pass Filter
Pulse Width
Guaranteed
to Not Pass
Filter
None — — — —
90 ns
(short)
100 MHz 9 90 ns 80 ns
5.12 µs
(medium)
100 MHz 512 5.12 µs 5.11 µs
2.56 ms
(high)
100 kHz 256 2.56 ms 2.55 ms
Custom User
configurable
N N/timebase (N - 1)/
timebase
12314123 45
RTSI, PFI, or
PXI_STAR Terminal
Filtered input goes
high when terminal
is sampled high on
five consecutive filter
clocks.
Filter Clock
Filtered Input

National Instruments 636 Series Specifications

General

Brand	National Instruments
Model	636 Series
Category	Data Loggers
Language	English