Highest-Reliability Digital I/O at the Lowest Cost

The new industrial digital I/O (DIO) devices from National Instruments offer a host of features to extend the reach of PC-based data acquisition to mission-critical industrial applications, and are powered by NI-DAQmx software technology for dramatic improvements in I/O performance and ease of use.

NI Continues to Set the Price-Performance Standard

The industrial digital input/output (DIO) devices from NI offer superior features at the lowest price for industrial control and manufacturing test applications such as factory automation, embedded machine control, and production line verification. With high current drive and isolation, you can connect the digital I/O devices directly to a wide array of industrial sensors and actuators. The NI digital I/O devices are designed from top to bottom to incorporate the latest hardware technologies and provide innovative features for applications requiring ease of use, high reliability, and performance. All of the industrial digital I/O devices take advantage of NI-DAQmx technology to speed up application development with many helpful features including NI DAQ Assistant, automatic code generation, and high-performance multithreaded streaming technology.

Device	Bus	Isolation	Voltage Range	Logic Levels	Sinking/ Sourcing	Current Drive	# Channels
NI 6501	USB	None	5 V	TTL CMOS	Both	8.5 mA	24 DIO
NI 6503	PCI, ISA, PCMCIA					2.5 mA
NI 6508	PCI, PXI, USB, ISA						96 DIO
NI 6509	PCI, PXI, USB					24 mA
NI 6511		Bank	30 V	24 V		-	64 DI
NI 6512				-	Sourcing	350 mA	64 DO
NI 6514				24 V			32 DI, 32 DO
NI 6513				-	Sinking	475 mA	64 DO
NI 6515				24 V			32 DI, 32 DO
NI 6510	PCI				Both	-	32 DI
NI 6516				-	Sourcing	350 mA	32 DO
NI 6518				24 V			16 DI, 16 DO
NI 6517				-	Sinking	475 mA	32 DO
NI 6519				24 V			16 DI, 16 DO
NI 6521	PCI, PXI	Ch-Ch	150 V		Both	2 A	8 DI, 8 DO
NI 6520	PCI		60 V
NI 6525	USB			5 V		500 mA
NI 6528	PCI, PXI					150 mA	24 DI, 24 DO
NI 6527			28 V			120 mA

The new low-cost digital I/O devices deliver high-reliability industrial feature set that includes digital I/O watchdogs, programmable power-up states, programmable input filters, isolation, and change detection. These features are particularly valuable for mission-critical industrial control and test and measurement applications, including discrete and batch process control in factory automation, machine control and production line automated test.

• Isolation protects hardware with direct connection to industrial sensors/actuators.
• Programmable input filters eliminate glitches/spikes and remove noise.
• Digital I/O watchdogs detect computer or application errors and ensure safe recovery.
• Programmable power-up states provide safe operation when connected to pumps/valves/motors/relays.
• Change detection triggers your application and returns I/O data after a digital event with minimal processor usage.

 

The NI-DAQmx Software Difference

The quality and productivity of software is the key to your ability to achieve success on your project in an efficient, timely manner. With NI-DAQmx driver software, you have full access to the state-of-the-art hardware technology in your digital I/O devices. NI-DAQmx technology speeds up your development with many features designed to make configuration and programming easy. NI digital I/O devices take advantage of the latest advances in driver software, such as multithreaded streaming technology.

NI-DAQ Measurement Services software is available for free of charge with all data acquisition NI hardware. This package includes NI-DAQmx technology, an innovative interface between hardware and software for dramatic improvements in I/O performance and ease of use.

• Use NI DAQ Assistant to guide you to fast, accurate measurements with no programming
• Use automatic code generation to create your application in NI LabVIEW, C, Visual Basic .NET, or C#
• Take advantage of multithreaded streaming technology for 1000X performance improvements
• Use automatic timing, triggering, and synchronization to make advanced applications easy
• Visit NI.COM for more than 3,000 FREE software downloads to jump-start your project
• Use NI-DAQmx functions for jumper-free software configuration of all digital I/O features (no hardware switches/jumpers)
• Develop your application with easy, open programming in LabVIEW, ANSI C, Microsoft Visual C++, C#, and Visual Basid .NET

  Use NI DAQ Assistant to Guide You
  

1. Install NI-DAQmx software and test your new NI digital I/O module

With the revolutionary NI-DAQmx software, no programming is necessary to install and test your NI digital I/O module. Just double-click the Measurement & Automation Explorer (MAX) icon that appears on your desktop after the installation of NI-DAQmx. MAX is a configuration tool designed to help you get up and running quickly. In MAX, open the Devices and Interfaces tab. You’ll find your digital I/O device listed under NI-DAQmx Devices. You can right-click on the module name to open Test Panels or select Properties to configure the Programmable Power-Up States.



Figure 1. Measurement & Automation Explorer (MAX)

Once you’ve verified that your device is installed and working properly, you are ready to configure an input/output task. Right click on the Data Neighborhood tab and select Create New. Select NI-DAQmx Task, click Next, and then choose Digital I/O. Then allow NI DAQ Assistant to guide you.

Figure 2. NI DAQ Assistant

Once you have launched NI DAQ Assistant, select Line Input to read one or more digital lines or Line Output to write one or more digital lines. Alternately, you can select Port Input or Port Output to read or write one or more groups of eight lines. Finally select the lines or ports on your NI digital I/O device and any additional settings such as change detection, as shown in Figure 3. If desired, you may choose to Test your digital I/O task.



Figure 3. NI-DAQmx Task for Digital I/O

Use NI DAQ Assistant in Any Language

You can use NI DAQ Assistant in LabVIEW 7 or later, LabWindows/CVI (C programming), Visual Basic .NET, or Microsoft C#. In the sections below, we will show you how to use launch NI DAQ Assistant to set up a digital I/O task in NI LabVIEW and Microsoft Visual Basic .NET with Measurement Studio.

Graphical Programming with LabVIEW

Launch LabVIEW and click the New button. On the templates browser, select Data Acquisition with NI-DAQmx.vi. Then double-click DAQ Assistant and it will guide through the configuration of your digital I/O task. When you are finished, right-click the data terminal to wire your digital I/O signal to a control or indicator such as a Digital Waveform Graph.

Figure 4. Using DAQ Assistant in LabVIEW

 

Text Programming with Microsoft Visual Basic .NET

Launch Microsoft Visual Studio 2003 or 2005 .NET with Measurement Studio. Measurement Studio delivers powerful data acquisition and analysis programming tools for Microsoft Visual Studio. Navigate to New » Project » Measurement Studio Projects » Visual Basic Projects. Select Windows Application. Follow the instructions and check the Launch the DAQmx Task Wizard box.



Figure 5. Using DAQ Assistant in Visual Basic .NET

Use NI-DAQmx to Write Your Code

If you are an advanced programmer who wants to obtain low-level access to your data acquisition and control code, you may wish to perform automatic code generation. You can use the DAQ Assistant to configure your I/O operation, and then generate native source code in your software language of choice. Development time for even the most advanced applications is reduced dramatically when you use NI-DAQmx to write your application software for you. The code automatically generated for digital I/O can then be integrated with your larger application or modified to suit your needs. For example, you may decide to add Programmable Input Filters to your automatically generated code.

Figure 6. Right-Click to Generate Code

 

 

Perform Automatic Code Generation in LabVIEW

To perform automatic code generation in LabVIEW, open a new VI and go to the block diagram. Then right-click on the block diagram and navigate to the NI Measurements » DAQmx Data Acquisition palette. Then drop down a DAQmx Task Name Constant, click on it and select Browse, and then select Create New. The DAQ Assistant will guide you through the set up of your digital I/O task. When you are finished, right click on the Task Name Constant and navigate to Generate Code » Example.

Figure 7. Automatic Code Generation in LabVIEW

Take Advantage of Multithreaded Streaming Technology
Multithreading is achieved automatically when you use the NI-DAQmx technology with LabVIEW. You can see up to 1000X performance improvements in applications with large channel counts. With multithreading, each I/O task runs independently and simultaneously for optimal performance.




Figure 8. Multithreading technology can increase performance up to 1000X.

Take Advantage of Automatic Timing, Triggering, and Synchronization

With the innovative NI-DAQmx driver software, engineers and scientists can access the full functionality of the new digital I/O devices. NI-DAQmx technology speeds up development with many built-in features designed to make configuration and programming easy. As an example, you can easily configure your digital I/O module to perform a read operation upon a trigger from a digital change of state event on one or more digital lines. This type of trigger is called change detection.

3,000 FREE Software Downloads
Jump-start your application development with more than 3000 free, easy-to-use LabVIEW, C, and Visual Basic measurement examples for analog and digital I/O, counter/timer operations, signal processing and analysis, and more. Plus, search on applications ranging from temperature and strain to sound and vibration to machine vision and motion control. You can save hours of development time when you find an example that closely matches your application, and you can easily customize the example programs. To get started, visit ni.com/devzone.

Jumper-Free Software Configuration
The new NI digital I/O devices are completely jumper-free and every feature is software configurable. Simply plug in your digital I/O module and configure the settings in MAX or your programming language of choice using the NI-DAQmx driver software.

Easy and Open Programming in Any Language
With the NI-DAQmx driver, you can use your NI device in a variety of software development environments, such as LabVIEW, ANSI C, Microsoft Visual C++, C#, and Visual Basic .NET. All applications environments share a single set of commands and functions, so your knowledge of a single programming methodology can be bridged to multiple programming languages.

NI Digital I/O High-Reliability Industrial Feature Set

All of the new digital I/O devices offer the following high-reliability features designed to automate even the most demanding applications:

• Isolation protects hardware with direct connection to industrial sensors/actuators.
• Programmable input filters eliminate glitches/spikes and remove noise.
• Digital I/O watchdogs detect computer or application errors and ensure safe recovery.
• Programmable power-up states provide safe operation when connected to pumps/valves/motors/relays.
• Change detection triggers your application and returns I/O data after a digital event with minimal processor usage.

Connect Sensors Directly with Isolation

Isolation is a form of built-in signal conditioning that provides several advantages. Isolation provides an extended voltage range for direct connection to industrial sensors and actuators. Isolation also improves signal quality and protects computer circuitry. Isolation physically and electrically separates two parts of a circuit, which breaks ground loops, improves common-mode voltage and noise rejection, and permits the two parts of the circuit to be at different voltage levels. Many industrial applications require isolation to protect the electronics from transient voltage spikes and provide greater common-mode noise rejection in electrically noisy environments containing machinery and inductive loads.

In the case of channel-to-channel isolated I/O, each channel has its own ground terminal. In bank-to-bank isolated devices, each bank (or group) of several channels share the same ground but are isolated from other banks.


Eliminate Glitches with Programmable Input Filters

Programmable input filters remove noise, glitches, and spikes on inputs, and also provide debouncing for digital switches and relays. This feature is important for applications in noisy industrial environments to prevent false readings based on noise. The programmable input filter for each digital line can be configured by setting the filter time in seconds. Any digital noise, glitch, or spike that is faster than the filter time will be ignored by the digital I/O device, preventing invalid readings or false triggers.



Figure 9. Digital I/O Programmable Input Filters


Detect and Recover with Digital I/O Watchdogs

NI digital I/O watchdogs are a completely new technology that provides protection against a variety of fault conditions.

• Computer crash -- total crash of the operating system
• Application crash -- software application ceases to respond
• PCI bus failure -- communications cease to respond

Watchdogs drive the digital outputs to a defined safe output state, allowing safe recovery. Watchdogs are important whenever the module is connected to actuators such as pumps, valves, motors, and relays. The digital I/O module monitors the software application and, if it fails to respond within the time limit, automatically sets the output lines to the safe state. For an example, launch the NI Example Finder in LabVIEW.

In the past, high reliability applications that required protection against these potential failure modes would have required expensive and complex fault-detection/response systems.

Figure 10. Digital I/O Watchdogs are Important for Mission-Critical Control Applications

Connect Safely to Actuators with Programmable Power-Up States
Using programmable power-up states, you can configure the initial output states of the digital I/O module in software. The digital I/O module holds these I/O states, while your computer boots and your software application begins running. This process ensures a safe start-up operation when connected to industrial actuators such as pumps, valves, motors, and relays. The programmable power-up states are glitch-free, meaning the outputs never go through an incorrect state during power up.

Each port and line can be configured as input, output high (true), or output low (false). The digital I/O module stores the settings in onboard nonvolatile memory and implements the power-up states instantaneously after power is applied to the device.

Figure 11. Programmable power-up states are configured in MAX.

 

Trigger Your Application with Change Detection

With change detection, you can automatically trigger your software application to perform a digital read operation upon a digital change of state. The digital I/O module notifies the software application when this event occurs, so no polling is necessary. Using change detection, you can monitor for digital events with minimal processor usage. No polling is necessary, because the digital I/O module generates an interrupt to automatically "wake up" your application.




Figure 12. Change Detection Triggering for Digital I/O

Best Digital I/O Value at the Lowest Cost

As a market leader for data acquisition in measurement and control, NI continues to set the price-performance standard by developing state-of-the-art technology, driving down costs, and passing the savings to our customers. NI offers a complete low-cost data acquisition solution with superior accuracy, reliability, software productivity, and support. To order an NI digital I/O module now, visit ni.com/digitalio online or call your local sales engineer.

See Also:
DAQ
Digital Input/Output Devices

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Plis document in spanish Plis!
- jorge decimo, Electricidad Decimo. decimoelectricidad@hotmail.com - Jan 13, 2004