Chapter 6
Digital I/O
6-2
ni.com
Fig
u
re 6-1 shows the circ
u
itry of one DI line and one DO line. The
following sections provide information abo
u
t the vario
u
s parts of the DIO
circ
u
it.
Figure 6-1.
USB-6210/6211/6215/6218 Digital I/O Circuitry
The DI terminals are named P0.<0..7> on the USB-6210/6211/6215/6218
device I/O connector. The DO terminals are named P1.<0..7> on the
USB-6210/6211/6215/6218 device I/O connector.
The voltage inp
u
t and o
u
tp
u
t levels and the c
u
rrent drive levels of the DIO
lines are listed in the
NI USB-621x Specifications
.
Static DIO on USB-6210/6211/6215/6218 Devices
Yo
u
can
u
se static DI and DO lines to monitor or control digital signals.
All samples of static DI lines and
u
pdates of DO lines are software-timed.
I/O Protection on USB-6210/6211/6215/6218 Devices
Each DI, DO, 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:
•
Do
not
connect a DO or PFI o
u
tp
u
t lines to any external signal so
u
rce,
gro
u
nd signal, or power s
u
pply.
•
Understand the c
u
rrent req
u
irements of the load connected to DO or
PFI o
u
tp
u
t 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.
•
Do
not
drive a DI or PFI inp
u
t line with voltages o
u
tside of its normal
operating range. The PFI or DI lines have a smaller operating range
than the AI signals.
S
t
a
tic DI
I/O Protection
47 k
Ω
P
u
ll-Down
P0.
x
I/O Protection
47 k
Ω
P
u
ll-Down
P1.
x
S
t
a
tic DO
