Connect Sensors Directly with Isolation

Isolation is a form of built-in signal conditioning that provides an

extended voltage range for direct connection to industrial sensors and

actuators. NI 6528 and PXI-6529 devices provide channel-to-channel

isolation where every channel is physically and electrically separated

from the others and earth ground. Optical isolators separate the high-

voltage front end from the low-voltage back end, breaking ground

loops, improving common-mode voltage rejection, and protecting

computer circuitry from hazardous voltages. Industrial environments

containing machinery and inductive loads require isolation to protect

the electronics from transient voltage spikes and provide greater

common-mode noise rejection.

Achieve Glitch-Free Startup with

Programmable Power-Up States

Using programmable power-up states, you can configure the initial

NI 6528 output states in software to ensure glitch-free operation

when connected to industrial actuators such as pumps, valves, motors,

and relays. An NI 6528 holds these output states after receiving power,

so your computer can boot and your software application can begin

running. Programmable power-up states are glitch-free, meaning the

outputs never go through an incorrect state during power up.

You can configure each individual digital line as high-output or

low-output. An NI 6528 stores the settings in onboard nonvolatile

memory and implements the power-up states instantaneously after

power is applied to the device.

Detect Faults and Recover with Digital

I/O Watchdogs

Digital I/O watchdog timers are an innovative technology that can

detect a variety of fault conditions, such as an application crash, and

automatically respond by setting the outputs to a user-configured safe

state. Watchdogs are important whenever the module is connected to

actuators such as pumps, valves, motors, and relays. An NI 6528

monitors the software application; if the application fails to respond

within a preset time limit, an NI 6528 automatically sets the output

lines to a user-defined safe state. An NI 6528 remains in the watchdog

state until the watchdog timer is disarmed, an NI 6528 is reset, or the

computer is restarted.

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. A digital change of state is defined as the rising edge

(0 to 1 transition) or falling edge (1 to 0 transition) on one or more

digital lines. 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.

Using NI-DAQmx software technology, NI 6528 and PXI-6529 devices

notify the software application when an event is detected, causing the

application to automatically perform a read operation. To minimize

the effects of noisy input lines, use programmable input filters in

combination with change detection to eliminate spurious change-

detection events caused by noise or glitches.

Eliminate Noise with Programmable

Input Filters

Programmable input filters remove noise, glitches, and spikes on

inputs as well as provide debouncing for digital switches and relays.

These features are important for applications in industrial environments

to prevent false readings caused by noise. You can configure the

programmable input filter for each digital line by setting the filter time.

NI 6528 and PXI-6529 devices block any digital noise, glitch, or spike

that is shorter than half of the specified filter time, preventing invalid

readings and false triggers for change-detection events.

Use High-Voltage Triggering

With NI 6528 and PXI-6529 devices, you can route isolated high-voltage

(±60 VDC) signals to the PXI trigger bus or RTSI (Real-Time System

Integration) bus, so you can synchronize between multiple high-voltage

devices without additional circuitry. This feature benefits automotive,

aerospace, and industrial monitoring and control applications needing

high-voltage triggers.

Recommended Software

National Instruments measurement services software, built around

NI-DAQmx driver software, includes intuitive application programming

interfaces, configuration tools, I/O assistants, and other tools designed

to reduce system setup, configuration, and development time. National

Instruments recommends using the latest version of NI-DAQmx driver

software for application development in National Instruments LabVIEW,

LabWindows/CVI, and Measurement Studio. To obtain the latest version

services software speeds up your development with features including:

• A guide to create fast and accurate measurements with no

programming using the DAQ Assistant

• Free LabVIEW SignalExpress LE data-logging software

• Automatic code generation to create your application in NI LabVIEW,

LabWindows/CVI, and LabVIEW SignalExpress as well as Microsoft Visual

Studio .NET, C/C++/C#, or Visual Basic using NI Measurement Studio

Industrial Digital Input/Output – 60 V, Channel-to-Channel Isolated

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