Low-Cost Industrial Digital I/O – 150 V
Eliminate Noise with
Programmable Input Filters
Software
NI-DAQmx Software Technology
Programmable input filters remove noise, glitches, and spikes on input,
and provide debouncing for digital switches and relays. This feature is
important for applications in noisy 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 in seconds.
Any digital noise, glitch, or spike that is shorter than half of the specified
filter time is blocked by the digital I/O device, preventing invalid readings
and false triggers for change detection events.
NI 6521 devices require and are shipped with NI-DAQmx driver software,
Version 7.5 or later. NI-DAQmx software is also available for download
from ni.com/downloads. With NI-DAQmx, you can use your NI digital
I/O device in NI LabVIEW, ANSI C, Microsoft Visual C++, and the
Microsoft .NET languages C# and Visual Basic .NET.
Using NI-DAQmx technology, you can access the full functionality
and state-of-the-art hardware technology of your NI 6521 digital I/O
devices. NI-DAQmx technology speeds up your development with
many features such as automatic code generation to make configuration
and programming easy. The NI 6521 devices take full advantage of key
NI-DAQmx software technologies such as multithreaded streaming
technology for dramatic improvements in I/O performance and ease of use.
• Use DAQ Assistant to guide you to fast, accurate measurements
with no programming.
Relay Forms
Relays are classified by number of poles and number of throws. The
pole of a relay is the terminal common to every path. Each position
where the pole can connect is called a throw. A relay can be made of
n poles and m throws. A single-pole single-throw (SPST) relay has one
pole and one throw. A single-pole double-throw (SPDT) relay has one
pole and two throws.
• Use automatic code generation to create your application in
LabVIEW, C, Visual Basic .NET, or C#.
• Take advantage of multithreaded streaming technology for
1,000X performance improvements.
Single-Pole Single-Throw (SPST) Relay
Single-Pole Double-Throw (SPDT) Relay
• Use automatic timing, triggering, and synchronization technology
to make advanced applications easy.
Figure 2. Relay Diagrams
Form
Symbol
Description
• Visit ni.com for more than 3,000 FREE software downloads to
jump-start your project.
Form A
SPST relay with a normally open default state
• Use the NI-DAQmx functions for software configuration of all
digital I/O features without hardware switches/jumpers.
• Develop your application with easy and open programming in
LabVIEW, ANSI C, Microsoft Visual C++, C#, and Visual Basic .NET.
Form C
SPDT relay that breaks the connection
with one throw before making contact with
the other (break-before-make)
Table 1. Relay Descriptions
Nonlatching Relays
Low-Cost 37-Pin Accessories
Several low-cost, high-voltage accessory options are available for
connecting to the 37-pin D-Sub connector of NI 6521 devices. NI 6521
devices ship with an accessory safety kit for keying connectors.
A nonlatching relay has a power-off initial position of normally closed
(NC). This position is maintained by the force of a spring or permanent
magnet while no current flows. The normally open (NO) contact is
maintained by the force of a magnetic field while current flows through
the coil. When the current stops, the relay reverts back to its initial NC
position. Nonlatching relays return to the default NC position in case of a
fault or power failure. This feature is particularly useful when controlling
a motor or valve where the motor or valve needs to be turned off in case
of power failure or fault.
BUY ONLINE at ni.com or CALL (800) 813 3693 (U.S.)
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NI [ National Instruments ]
