Chapter 4
Signal Connections
©
National Instruments Corporation
4-11
6711/6713/6715 User Manual
Power Connections
Two pins on the I/O connector 5 V from the computer power
supply through a self-resetting fuse. The fuse will reset automatically
within a few seconds after the overcurrent condition is removed. You can
use these pins, referenced to DGND, to power external digital circuitry.
•
Power rating: +4.65 to +5.25 VDC at 1 A (0.75 A, DAQCard-6723)
1
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 671X device or any other
device. Doing so can damage the 671X 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 671X device and the computer. National Instruments is not liable for any
damages resulting from such signal connections.
All external control over the timing of the 671X device is routed through
the 10 programmable function inputs labeled PFI0 through PFI9. These
signals are explained in detail in the next section,
Programmable Function
Input Connections
. These PFIs are bidirectional; as outputs they are not
programmable and reflect the state of many DAQ, waveform generation,
and general-purpose timing signals. On 671X device, six PFIs are
bidirectional and four PFIs are input only (PFI0, PFI1, PFI2, PFI7). There
are four other dedicated outputs for the remainder of the timing signals (on
the 671X SCANCLK is not used). As inputs, the PFI signals are
programmable and can control any DAQ, waveform generation, and
general-purpose timing signals.
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
General-Purpose
Timing Signal Connections
section later in this chapter.
1
The +5 V line on the connector of the DAQCard-6715 is fused at 0.75 A, however, the actual current available can be limited
below this value by the host computer. National Instruments recommends limiting current from this line to 250 mA.
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