Data Acquisition Toolbox

Digital Input/Output

Digital I/O (DIO) subsystems are designed to input and output digital values to and from hardware. These values are typically handled either as single bits or lines, or as a port, which typically consists of eight lines. While most popular data acquisition boards include some digital I/O capability, it is usually limited to simple operations and special dedicated hardware is required for performing advanced digital I/O operations. The Data Acquisition Toolbox provides access to digital I/O subsystems through a digital I/O object.

Note    The Data Acquisition Toolbox does not directly support buffered digital I/O or handshaking (latching). However, you can write your own M-code to support this functionality. Buffered digital I/O means that the data associated with a digital I/O subsystem is stored in the engine. Handshaking allows your digital I/O subsystem to input or output data after receiving a digital pulse.

The purpose of this chapter is to show you how to perform data acquisition tasks using your digital I/O hardware. Topics include:

• Creating a digital I/O object
• Adding lines to a digital I/O object
• Writing and reading digital I/O line values
• Generating timer events
• Evaluating the digital I/O object status

Starting Multiple Device Objects

Creating a Digital I/O Object