About Open Collectors
Open Collector Outputs are used primarily for the purposes of controlling external DC relays and some very small DC solenoids. An open collector output is different than a relay output. Open collector outputs allow the user to control the connection of an external device by connecting and disconnecting the ground wire under software control. To drive an external 12V relay, +12V should be connected to one side of the relay at all times. The other side of your relay should be connected to our Open Collector output. Use our open collector outputs to make the connection to ground under software control. Open Collector outputs are also known as low side drivers (meaning it switches the ground line). In this way, different devices of different voltages may be controlled, providing all power supplies can share a common ground. A relay can provide you with a simulated open collector output by simply by connecting one of the relay outputs to your power supply ground. For wiring diagrams, please see the XR manual page 8.
ProXR Controllers were built with relay expansion in mind. Easily add different types of relays for high-power, signal, general purpose, or solid-state switching. The XR Expansion Port allows you to also add expansion boards and control up to 256 relays.
Above: A 4-channel ProXR Series Controller (bottom) shown with an 8-channel expansion board attached.
Simply chain the XR Expansion Modules, one after another, to add additional relays to any ProXR board up to 256 relays.
XR Expansion Port
XR Relay Expansion Controllers add a large variety of relay switching capabilities to an existing NCD ProXR series controller.
The XR Expansion Port is used to add banks of external relays to a ProXR Controller equipped with a XR Expansion port. As we continue to develop new devices, a modular architecture will be implemented, offering the greatest amount of user flexibility.
Controlling XR Expansion Banks
FXR Expansion Boards have no on-board brains. They are entirely reliant on the brains of a “master” ProXR device. The XR Expansion Modules have many possibilities:
- Adds up to 256 Relays to a ProXR Series Controllers
- Mix and Match Relay Types to Suite your Application Needs
- Choose Between Mechanical and Solid-State Relay Types
- Choose DPDT Relays for Signal Switching Applications
Linking XR Expansion Boards Together
XR Expansion Controllers consist of a XR Input and XR Output Connector. Simply connect the XR Output of your ProXR Controller to the XR Input located on the relay expansion board. Chaining more relays is easy. Simply connect the XR Output of your ProXR expansion board to the XR Input of your next relay expansion. Mix and Match different relay types as your application requires.
We always include a 6″ expansion cable with your expansion board. We can provide longer cables if needed, but it’s important to keep the cabling as short as possible. Not all users will be able to expand to 256 total relays, as it all depends on the installation, the amount of electrical interference, and the overall cable length. For best compatibility, the total length of the ProXR controller and all of the expansions and cabling should not exceed 1 or 2 meters.