Chapter 4
Signal Connections
PCI-4451/4452/4453/4454 User Manual
4-18
www.ni.com
Digital Power Connections (PCI-4451/4452 Only)
Four pins on the digital I/O connector 5 V (+4.65 to +5.25 VDC at
1 A) from the computer power supply through a self-resetting fuse. The
fuse resets automatically within a few seconds after an overcurrent
condition is removed. These pins are referenced to DGND and you can use
them to power external digital circuitry.
Caution
Do not under any circumstances connect these +5 V power pins directly to analog
ground, digital ground, or to any other voltage source on the PCI-4451/4452 or any other
device. Doing so can damage the PCI-4451/4452 device and the computer. National
Instruments is not liable for damages resulting from such a connection.
Timing Connections
♦
PCI-4451/4452
All external control over the timing of your PCI-4451/4452 is routed
through the 10 programmable function inputs labeled PFI0 through PFI9
(excluding PFI2 and PFI5) and through the RTSI bus. See Figure 3-9,
, for a list of these signals. These signals are
explained in detail in the next section,
Connections (PCI-4451/4452 Only)
. Most of these PFIs are bidirectional.
As outputs, they are not programmable and reflect the state of acquisition,
waveform generation, and general-purpose timing signals. As inputs, the
PFI signals are programmable and can control any acquisition, waveform
generation, and general-purpose timing signals.
♦
PCI-4453/4454
Since the PCI-4453/4454 has no digital connector, timing signals can only
be routed to the RTSI bus. See Figure 3-9,
.
♦
PCI-4451/4452/4453/4454
The acquisition signals are explained in the
section in this chapter. The waveform generation signals are
explained in the
Waveform Generation Timing Connections
section in this
chapter. The general-purpose timing signals are explained in the
General-Purpose Timing Signal Connections
section in this chapter.
All digital timing connections are referenced to DGND.
