Chapter 6
Digital I/O
©
National Instruments Corporation
6-5
Figure 6-3.
USB-6212/6216 Digital I/O Circuitry
The following sections provide information abo
u
t the vario
u
s parts of the
DIO circ
u
it.
Static DIO on USB-6212/6216 Devices
Each of the USB-6212/6216 DIO lines can be
u
sed as a static DI or DO
line. Yo
u
can
u
se static DIO lines to monitor or control digital signals.
Each DIO can be individ
u
ally config
u
red as a digital inp
u
t (DI) or digital
o
u
tp
u
t (DO).
All samples of static DI lines and
u
pdates of DO lines are software-timed.
I/O Protection on USB-6212/6216 Devices
Each DIO and PFI signal is protected against overvoltage,
u
ndervoltage,
and overc
u
rrent conditions as well as ESD events. However, yo
u
sho
u
ld
avoid these fa
u
lt conditions by following these g
u
idelines:
•
If yo
u
config
u
re a PFI or DIO line as an o
u
tp
u
t, do
not
connect it to any
external signal so
u
rce, gro
u
nd signal, or power s
u
pply.
•
If yo
u
config
u
re a PFI or DIO line as an o
u
tp
u
t,
u
nderstand the c
u
rrent
req
u
irements of the load connected to these signals. Do
not
exceed the
specified c
u
rrent o
u
tp
u
t limits of the DAQ device. NI has several signal
conditioning sol
u
tions for digital applications req
u
iring high c
u
rrent
drive.
•
If yo
u
config
u
re a PFI or DIO line as an inp
u
t, do
not
drive the line with
voltages o
u
tside of its normal operating range. The PFI or DIO lines
have a smaller operating range than the AI signals.
•
Treat the DAQ device as yo
u
wo
u
ld treat any static sensitive device.
Always
properly gro
u
nd yo
u
rself and the eq
u
ipment when handling the
DAQ device or connecting to it.
Digit
a
l Line Direction Control
S
t
a
tic DI
I/O Protection
We
a
k P
u
ll-Down
P0.
x
S
t
a
tic DO
B
u
ffer
