National Instruments NI USB-621x - Manual (Page 119)

© National Instruments Corporation 10-1 NI USB-621x User Manual
10
PFI
NI 621x devices have up to eight input and eight output Programmable
Function Interface (PFI) signals, which also can be used as static digital
input or static digital output signals.
Each input PFI can be individually configured as the following:
• A static digital input
• A timing input signal for AI, AO, or counter/timer functions
Each output PFI can be individually configured as the following:
• A static digital output
• A timing output signal from AI, AO, or counter/timer functions
Each PFI input also has a programmable debouncing filter. Figure 10-1
shows the circuitry of an input PFI line.
Figure 10-1. NI 621x PFI Input Circuitry
Figure 10-2 shows the circuitry of an output PFI line.
Static DI
I/O Protection
To Input Timing
Signal Selectors
PFI
Filters
Weak Pull-Down
PFI <0..3>/P0,
PFI <8..11>/P0
Isolation
Barrier
(USB-6215
and USB-6218
devices only)
Digital
Isolators