Using Pfi Terminals As Timing Input Signals - National Instruments NI USB-621x User Manual

Chapter 10 PFI
and USB-6218
devices only)
Timing Signals

Using PFI Terminals as Timing Input Signals

NI USB-621x User Manual
Isolation
Barrier
(USB-6215
Digital
Isolators
Static DO
Buffer
When a terminal is used as a timing input or output signal, it is called PFI x.
When a terminal is used as a static digital input or output, it is called P0.x
or P1.x. On the I/O connector, each terminal is labeled PFI x/P0 or
PFI x/P1.
The voltage input and output levels and the current drive levels of the PFI
signals are listed in the specifications of your device.
Use PFI terminals to route external timing signals to many different
M Series functions. Each input PFI terminal can be routed to any of the
following signals.
• AI Convert Clock
• AI Sample Clock
• AI Start Trigger
• AI Reference Trigger
• AI Pause Trigger
• AI Sample Clock Timebase
• AO Start Trigger
• AO Sample Clock
• AO Sample Clock Timebase
• AO Pause Trigger
• Counter input signals for either counter—Source, Gate, Aux,
HW_Arm, A, B, Z
47 kΩ Pull-Down
Direction Control
Figure 10-2. NI 621x PFI Output Circuitry
10-2
PFI <4..7>/P1,
I/O Protection
PFI <12..15>/P1
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