National Instruments Multifunction RIO NI R Series, User Manual

Page: 37 / 71

Chapter 2 Hardware Overview of the NI 78xxR
R Series Multifunction RIO User Manual 2-18 ni.com
NI 7830R has one RMIO and one RDIO connector for a total of 56 DIO
lines. The NI 7831R/7833R/784
x R/785 x R has one RMIO and two RDIO
connectors for a total of 96 DIO lines.
Refer to Fig
u
re A-1, NI 781xR Connector Pin Assignments and Locations ,
for the connector locations and the I/O connector pin assignments on the
NI 781
x R. Refer to Fig
u
re A-2, NI 783xR/784xR/785xR Connector Pin
Assignments and Locations , for the connector locations and the I/O
connector pin assignments on the NI 783 x R/784 x R/785 x R.
The DIO lines on the NI 78 xx R are TTL-compatible. When config
u
red as
inp
u
ts, they can receive signals from 5 V TTL, 3.3 V LVTTL, 5 V CMOS,
and 3.3 V LVCMOS devices. When config
u
red as o
u
tp
u
ts, they can send
signals to 5 V TTL, 3.3 V LVTTL, and 3.3 V LVCMOS devices. Beca
u
se
the digital o
u
tp
u
ts provide a nominal o
u
tp
u
t swing of 0 to 3.3 V
(3.3 V TTL), the DIO lines cannot drive 5 V CMOS logic levels.
To interface to 5 V CMOS devices, yo
u
m
u
st provide an external p
u
ll-
u
p
resistor to 5 V. This resistor p
u
lls
u
p the 3.3 V digital o
u
tp
u
t from the
NI 78 xx R to 5 V CMOS logic levels. Refer to the NI R Series Multifunction
RIO Specifications , available at
ni.com/manual
s
, for detailed DIO
specifications.
Caution Exceeding the maxim
u
m inp
u
t voltage ratings, listed in Table A-2, NI 78xxR I/O
Signal Summary , can damage the NI 78 xx R and the comp
u
ter. NI is not liable for any
damage res
u
lting from s
u
ch signal connections.
Caution Do not short the DIO lines of the NI 78 xx R directly to power or to gro
u
nd. Doing
so can damage the NI 78 xx R by ca
u
sing excessive c
u
rrent to flow thro
u
gh the DIO lines.
Yo
u
can connect m
u
ltiple NI 78 xx R digital o
u
tp
u
t lines in parallel to
provide higher c
u
rrent so
u
rcing or sinking capability. If yo
u
connect
m
u
ltiple digital o
u
tp
u
t lines in parallel, yo
u
r application m
u
st drive all of
these lines sim
u
ltaneo
u
sly to the same val
u
e. If yo
u
connect digital lines
together and drive them to different val
u
es, excessive c
u
rrent can flow
thro
u
gh the DIO lines and damage the NI 78 xx R. Refer to the NI R Series
Multifunction RIO Specifications , available at
ni.com/manual
s
, for more
information abo
u
t DIO specifications. Fig
u
re 2-11 shows signal
connections for three typical DIO applications.