Understanding DAQ Systems: Basics of Data Acquisition and NI-DAQmx Configuration
This guide provides an overview of data acquisition (DAQ) systems, focusing on how to set up and configure DAQ devices using NI-DAQmx. It covers the fundamentals of data acquisition, the types of DAQ devices available, and the process of creating tasks in Measurement and Automation Explorer (MAX). Additionally, it explains how to integrate NI-DAQmx tasks in LabVIEW and introduces concepts related to counters and measuring signals. This resource is essential for anyone looking to understand the interfacing of digital electronics with computers.
Understanding DAQ Systems: Basics of Data Acquisition and NI-DAQmx Configuration
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Presentation Transcript
Digital Electronics and Computer Interfacing Tim Mewes 5. Computer Interfacing – DAQ cards
5.1 Basics • Data acquisition is the process of gathering a signal and digitizing it for presentation, analysis and storage on a computer • Signals can be either Analog or Digital Digital Electronics and Computer Interfacing
5.1 Basics • Today a wide variety of different DAQ devices are available: • PCI cards • PCMCIA cards (Notebooks) • USB solutions are becoming popular • Most DAQ devices allow to acquire and create signals (Input/Output) Digital Electronics and Computer Interfacing
5.2 DAQ Setup • DAQ setup can be done using the Measurement and Automation Explorer (MAX) • MAX also allows to test basic hardware functionality • The latest version of DAQ device drivers are called NI-DAQmx • A DAQ setup configuration is calledNI-DAQmx task Digital Electronics and Computer Interfacing
5.2.1 Creating a new NI-DAQmx task • Open MAX • Go to devices &Interfaces • Select NI-DAQmx devices • Choose the card you want to use for the task(NI PCI-6014) • Select “Create Task” Digital Electronics and Computer Interfacing
5.2.1 Creating a new NI-DAQmx task • Select the type of taskyou need (Digital I/O) • Select whether you want to input or output data(example: Line Output) • Select the physical channels you want to use(example: P0.0 – P0.3) • Name the task • Select Finish and thentest the hardware Digital Electronics and Computer Interfacing
5.2.2 Using a NI-DAQmx task in LabVIEW • Go to Measurement I/ONI-DAQmx • Choose Read or Write • Create a constant for the task input • Select the task to be used as the constant Digital Electronics and Computer Interfacing
5.2.2 Using a NI-DAQmx task in LabVIEW • Configure the SubVI toinput/output data as needed The NI-DAQmx VIs are examples for so called polymorphic VIs Digital Electronics and Computer Interfacing
Polymorphic VIs • Polymorphic VIs accept different data types for a single input or output terminal • Polymorphic VIs automatically adapt to accept input data of different data types Digital Electronics and Computer Interfacing
5.3 Counter • A counter is a digital timing device • Can be used to • Count rising and/or falling edges • Measure the frequency/period of a signal • Measure the pulse width of a signal • The count register stores the current count of the counter • Counter gates can be used to externally enable/disable counting Digital Electronics and Computer Interfacing
5.3.1 Creating a NI-DAQmx counter task • Open MAX • Select “Create Task” • Choose “Counter Input” • Example: “Frequency” • The NI PCI-6014 has two counters choose one of them Digital Electronics and Computer Interfacing
5.3.1 Creating a NI-DAQmx counter task • Modify the task properties if necessary • Save the settings • Note the PIN to which the signal has to be connected! • Make the physical connection • Test it Digital Electronics and Computer Interfacing
