Chapter 4
Signal Connections
4-20
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Power Connections
Two pins on the I/O connector 5 V from the computer power
supply via a self-resetting fuse. The fuse will reset automatically within a
few seconds after the overcurrent condition is removed. These pins are
referenced to DGND and can be used to power external digital circuitry.
The power rating is +4.65 to +5.25 VDC at 1 A.
Caution
Under no circumstances should you connect these +5 V power pins directly to
analog or digital ground or to any other voltage source on the device or any other device.
Doing so can damage the device and the computer. National Instruments is not liable for
damages resulting from such a connection.
Timing Connections
Caution
Exceeding the maximum input voltage ratings, which are listed in Table 4-2, can
damage the device and the computer. National Instruments is not liable for any damages
resulting from such signal connections.
All external control over the timing of your device is routed through the 10
programmable function inputs labeled PFI<0..9>. These signals are
explained in detail in the section,
. These PFIs are bidirectional; as outputs they are not
programmable and reflect the state of many DAQ, waveform generation,
and general-purpose timing signals. There are five other dedicated outputs
for the remainder of the timing signals. As inputs, the PFI signals are
programmable and can control any DAQ, waveform generation, and
general-purpose timing signals.
The DAQ signals are explained in the
later in this chapter. The waveform generation signals are explained in the
Waveform Generation Timing Connections
section later in this chapter.
The general-purpose timing signals are explained in the
All digital timing connections are referenced to DGND. This reference
is demonstrated in Figure 4-10, which shows how to connect an external
TRIG1 source and an external CONVERT* source to two PFI pins.
