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National Instruments PCI-6221 PFI Digital Input

PFI Digital Input block for PCI-6221 and PXI-6221 boards


Simulink® Real-Time™ Library for National Instruments®


A model can have more than one PFI digital input block for a given physical board. If a model has more than one digital input block, it executes the blocks in the order that the Simulink software has determined.

The two counters and the PFI digital input and output blocks share the 16 PFI digital I/O lines. Follow these rules when using these blocks:

You can read a PFI bit with this digital input block when...You cannot read a PFI bit with this digital input block when...
PWM measure block is using the bitPWM generate block is using the bit
Incremental encoder block is using the bit PFI digital output block is using the bit

Scaling of Input to Output

I/O Module Input

Block Output Data Type




TTL low ≥ 0.0
TTL high = 1.0

Block Parameters

PFI bit vector (0-15)

This block uses 0 based numbering to reflect the names of the bits described in the National Instruments M Series user manual.

Enter a vector that contains the bits you want to monitor. For example, to read bits PFI 0, PFI 5, and PFI 7, enter

[0, 5, 7]

Sample time

Enter the base sample time or a multiple of the base sample time (-1 means sample time is inherited).

PCI slot (-1:autosearch)

If only one board of this type is in the target computer, enter -1 to locate the board.

If two or more boards of this type are in the target computer, enter the bus number and the PCI slot number of the board associated with this driver block. Use the format [BusNumber,SlotNumber].

To determine the bus number and the PCI slot number, type:

tg = slrt;
getPCIInfo(tg, 'installed')

See Also

External Websites

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