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National Instruments Corporation
7-1
DAQ-STC Technical Reference Manual
7
Digital I/O
7.1 Overview
This chapter describes the digital I/O (DIO) module and explains how to use it on the
DAQ-STC. The DIO module contains eight high-current bidirectional digital I/O lines and
serial I/O shift registers. The EXTSTROBE/SDCLK signal serves as the shift clock in the
serial mode. Eight additional output lines, CTRL<0..7>, are provided for use as a board-level
control register. Four additional lines, STATUS<0..3>, are provided for use as a board-level
status register.
7.2 Features
The DIO module has the following features:
•
Eight individually programmable bidirectional lines
•
24 mA sink current, 13 mA source current
•
Serial I/O support for SCXI serial link on digital I/O lines
•
Control and Status Registers
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8 output lines for use as a board-level control register
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4 input lines for use as a board status register
7.3 Simplified Model
The DIO module contains the hardware necessary to perform serial and parallel digital I/O,
as well as support for a status and control register interface. Figure 7-1 shows a simplified
model of the DIO module.