National Instruments PCI-6281 Digital Output

Digital Output block for PCI-6281 and PXI-6281 boards


Simulink® Real-Time™ Library for National Instruments®


Models can have multiple digital output blocks for one physical board. In this case, the Simulink Real-Time environment executes the blocks based on their sorted order as determined by the Simulink software.

Each board has one set of digital I/O ports. You can independently configure each port to be input or output.

If a digital input block shares channels with a digital output block, the input block reads the last value written to the digital output block on the overlapping channels.

The block compares the value written to each port with 0.5.

Value writtenBlock writes digital output with a value of...
>= 0.51

Scaling of Output to Input

I/O Module Output

Block Input Data Type




< 0.5 = TTL low
≥ 0.5 = TTL high

Block Parameters

Channel vector

Enter numbers between 1 and 8 to select the digital output lines used with this port. This driver allows the selection of individual digital output lines in arbitrary order. The number of elements defines the number of digital lines used.

For example, to use the first eight digital outputs, enter


Number the lines beginning with 1 even if this board manufacturer starts numbering the lines with 0.

Reset vector

The reset vector controls the behavior of the channel at model termination. Enter a scalar or a vector that is the same length as the channel vector. If you specify a scalar value, that setting is replicated over the channel vector. If you specify a value of 1, the corresponding channel is reset to the value specified in the initial value vector. If you specify a value of 0, the channel remains at the last value attained while the model was running.

Initial value vector

The initial value vector contains the initial values (0 or 1) of the output channels. Enter a scalar or a vector that is the same length as the channel vector. If you enter a scalar, that value is replicated as the initial value over the channel vector. The channels are set to these initial values between the time the model is downloaded and the time it is started.

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')

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