National Instruments PCI-6601, User Manual

Page: 28 / 52

Chapter 3 Signal Connections
© National Instruments 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 NI 660 x devices
when the lines p
u
lled
u
p or down are
u
sed as o
u
tp
u
ts.
I/O Connector Pinout
Fig
u
re 3-2 shows the pino
u
t of the NI 6601. Fig
u
re 3-3 shows the pino
u
t of
the NI 6602/6608. The descriptions beside each pin are in the following
format: Signal Name / DIO Context / Co
u
nter Context (Defa
u
lt).
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