Chapter 3
Signal Connections
©
National Instruments Corporation
3-3
Note
If possible, camera power should be provided through the ATX connector inside the
computer. If you cannot supply camera power through the ATX connector, camera power
is supplied by the PCI Express bus and should be limited to 3 W, shared by both ports.
General-Purpose Digital I/O
The 44-pin D-SUB connector provides access to the general-purpose
digital inputs and outputs and the isolated power supply. The
general-purpose digital I/O available on this connector includes 2 TTL
inputs, 10 TTL outputs, 13 isolated inputs, and 4 isolated outputs. In
addition to I/O, the 44-pin D-SUB connector provides access to V
iso
and
C
iso
for powering the isolated outputs with an external power supply. The
orange LED on the front panel of the NI 8255R illuminates when power for
the isolated outputs is present. For easy connection to the digital I/O
connector, use the National Instruments digital I/O cable and the NI Vision
I/O Terminal Block and Prototyping Accessory.
Note
The accessories available for use with the NI 8255R do
not
provide access to all
available I/O on the NI 8255R device. To access this I/O, you can create a custom cable
using a standard male 44-pin D-SUB connector.
For more information about the National Instruments digital I/O cable
and terminal blocks, refer to the
Optional Equipment
section of
Getting
Started with the NI PCIe-8255R
.
Note
Isolated inputs are compatible with 5 V logic if the external circuit meets the voltage
and current requirements listed in the
Specifications
section of
Getting Started with the
NI PCIe-8255R
.
Caution
Do
not
draw more than 100 mA from 24 V or 30 V isolated outputs. Do
not
draw
more than 50 mA from 5 V isolated outputs.