control anything... anywhere
National Control Devices, LLC

DPDT Relay Controllers

DPDT Relay Controllers

DPDT Relay

Relay Boards with DPDT Relays Installed

Double Pole Double Throw Relay

A DPDT Relay, Double Pole Double Throw Relay, has a single coil with two arms that move at the same time.  There are two completely separate SPDT switch mechanisms inside a DPDT relay.  A DPDT relay board is most commonly used for signal switching applications, but can be found in high power switching applications as well.

Content on this page requires a newer version of Adobe Flash Player.

Get Adobe Flash player

Data Collection and Control with Future Expandability in Mind. This ProXR Series Controller is Feature Rich and Ready to Grow with your Needs!
    Summary of DPDT Relays
  • 1, 3, or 5 amp versions available
  • A/D Versions available
  • UPS Port available on select models
  • Many computer interface options available
  • ProXR versions can expand to 256 total relays
  • Add A/D, contact closure or Potentiometer to
    any UXP version

DPDT Relay

DPDT Relay

Our DPDT boards offer your choice of 1, 3 or 5 amp relays and are available with your choice of eight channel 8/10-Bit Analog to Digital Conversion or UXP Expansion Port on selected models, look for AD or UXP in the part number. All are of course SignalSwitch compatible.  Select Wireless Relays feature the ProXR Command Set and an XR Expansion Port, simply look for PROXR in the part number.  The XR Expansion Port will allow you to expand any ProXR model board to 256 relays using our XR Expansion Modules.  The UXP port will allow you to add Analog to Digital Expansion Modules, Contact Closure Input Modules or Digital Potentiometers to any UXP board.


New to Computer Controlled Relay? Click the following links for helpful wireless articles to get you started.

A/D Conversion
Wireless Analog to Digital Converter
UXP Expansion
UXP Expansion Port
XR Expansion
ProXR versions
Wireless Relay with Analog to Digital Conversion Wireless Relay with UXP Expansion Port Wireless Relay with XR Expansion Port

Onboard analog to digital conversion is available on selected models of these controllers! This will allow you to:

  • Read light and temperature levels
  • Easily activate relays when A/D limits are reached
  • Detect audio levels in a room when connected to a microphone
  • Read switches, potentiometers, and analog joysticks
  • applications are limitless, and surprisingly easy to integrate
  • Available on select boards

UXP is a new standardized data port, specifically for the purpose of speaking to various expansion modules. If the controller you are considering is equipped with a UXP port, you can take advantage of extended commands to speak to our growing line of I/O expansion modules. UXP in the part number allows you to:

  • Add Contact Closure Inputs
  • Add Analog to Digital Inputs
  • Add Voltage Detectors
  • Digital Potentiometer Outputs
  • Available on select boards

Models with the ProXR suffix will feature the ProXR commend set. The ProXR series will allow you to:

NCD Component Library

Download NCD Component Library

By downloading the NCD Component Library you will receive over 40 samples from A/D Conversion to Duration and Pulse Timing and best of all it's FREE!! We want the user to be able to experiment with all the different samples available so as of right now the samples cannot be downloaded individually. 

We've "Started" the Programming for You

With the NCD Component Library we've "started" the programming for you.  We say started because these are fully functioning samples but we've also included the source code so you can customize them to your exact needs.  Start by downloading the file from the NCD Component page.
Download NCD Component Library

Over 40 samples included with this download!  To view screen shots of each example visit our NCD Component Library Page.


This video is a basic introduction to the world of Computer Controlled Switching and Relays in general.
Also read our "Introduction to Computer Control" Article.


Watch to find out the advantages of wireless communications and the differences between wireless communications.
Also read our Articles on Communication Protocols.


This video will show you what Induction is and how to use Capacitors to Suppress it.
Also read our Article on Induction Suppression.


Learn about the mechanics, applications, and tricks to Analog to Digital Conversion.
Also read our Article on Analog to Digital Conversion.


This movie will show you how to find the Com Port assigned to your Relay Controller.
The first half of the video will show you how to do so in Windows Vista and the second half is using Windows XP.