Sensor Activated Relay Controller

"Intelligent Relay Control Starts Here!"

Configure with USB. Operate Automatically

Every Reactor Controller is configured using the included Base Station Software and a imple USB connection. Create your automation using an easy point-and-click interface, upload the configuration to the controller, and disconnect the computer.

Once configured, the Reactor continuously monitors connected sensors and contact closure inputs, automatically controlling relays according to the conditions you've defined. Need to make changes? Simply reconnect the USB cable, update your configuration, and upload it to the controller.

---

Intelligent Relay Automation

Reactor Controllers go far beyond turning relays on and off. Configure sensor thresholds that activate relays above, below, or within a specific operating range. Add programmable time delays to keep equipment running after an event or automatically turn outputs off after a preset time.

Whether you're controlling a fan, pump, warning light, or alarm, Reactor continues making decisions long after the computer has been disconnected.

---

Build Powerful Automation

As your application grows, Reactor grows with it.

Configure up to 8 independent background timers and 4 rotation counters to create sophisticated automation routines. Timers can activate relays for precise durations, while rotation counters make it easy to alternate equipment, sequence relays, or create repeating operations.

Need even more flexibility? Event Piping allows timers and rotation counters to trigger additional events, making complex relay automation possible without writing software.

---

Monitor Eight Sensor Inputs

Every Reactor Controller continuously monitors 8 analog or contact closure inputs. Connect sensors operating from 0 to 5 VDC, switches, or dry contacts and define exactly how Reactor should respond.

Each input can independently trigger relays, timers, or automation sequences, allowing a single controller to monitor multiple sensors simultaneously.

---

Precision Trigger Control

Reactor converts each 0 to 5 VDC input into 256 programmable trigger levels, allowing precise control over when events occur.

Instead of simply reacting to ON and OFF signals, you can configure trigger points above, below, or within a specific sensor range. This provides exceptional flexibility for monitoring temperature, pressure, liquid level, light intensity, and countless other analog sensors.

---

USB Communications

The Reactor connects to your computer through USB and appears as a standard COM port, making configuration quick and reliable. USB drivers are included with the Base Station Software and are also available in the Resources section.

After configuration is complete, the USB cable can be disconnected while Reactor continues operating autonomously.

Base Station Reactor Configuration

"Configure to fit your application needs."

Build Automation Without Programming

The Reactor Controller is configured using the included Base Station Software, making it easy to build everything from simple relay triggers to sophisticated automation routines without writing a single line of code.

Using a point-and-click interface, you can define how sensors trigger relays, create programmable time delays, build relay sequences, and configure advanced automation that continues running long after the computer has been disconnected.

---

Every Input Can Make a Decision

Each of the Reactor's eight inputs can monitor a sensor, switch, or contact closure and respond based on the conditions you define.

Configure an input to:

• Trigger above a sensor level
• Trigger below a sensor level
• Trigger within a specified range
• Trigger outside a specified range
• Activate a relay directly
• Start a timer
• Trigger another automation event

The possibilities extend far beyond simple ON and OFF control.

---

Build Logic That Fits Your Application

Reactor separates inputs, events, and relays, giving you tremendous flexibility.

An input doesn't have to turn on a relay immediately.

Instead, an input can:

• Start a timer
• Increment a rotation counter
• Trigger another event
• Activate one or several relays
• Begin a sequence of operations

This allows you to build sophisticated automation using a simple graphical interface instead of custom programming.

---

Flexible Relay Control

Every relay can respond to an input, timer, rotation counter, or automation event.

Configure relays to:

• Turn ON
• Turn OFF
• Toggle
• Follow the input state
• Operate opposite the input state

Or assign multiple relays to the same event for coordinated equipment control.

---

Grow From Simple to Sophisticated

Start with a single sensor controlling one relay.

Then expand to timers, relay sequencing, alternating equipment, and complex automation routines using Event Piping and internal events.

Whether your application requires a simple temperature-controlled fan or a multi-step automation process, Reactor grows with your requirements without requiring custom software development.

---

Computer Control When You Need It

Although Reactor is designed to operate autonomously, a connected computer can temporarily take control at any time.

Monitor sensor values, manually operate relays, trigger events, update configurations, or return control back to the Reactor's onboard logic whenever needed.

Reactor Technical Specs

"From Sensor Input to Intelligent Relay Control"

How Reactor Makes Decisions

Reactor Controllers continuously monitor eight analog inputs and convert incoming voltages into digital values. The onboard processor continuously compares those values against your programmed conditions, then executes relay actions, timers, rotation counters, or event sequences. All decision making occurs locally on the controller, eliminating the need for a continuously connected computer.

---

Input Voltage Changes

Reactor analog inputs are designed to detect very small voltage changes with 8-bit resolution.  In the case of a Reactor controller, analog inputs have an 8-bit resolution, meaning the voltage input (from 0 to 5VDC) is interpreted as a value from 0 to 255.

For Example
• A voltage input of 0 Volts is interpreted as a value of 0
• A voltage input of 2.5 Volts is interpreted as a value of 128
• A voltage input of 5 Volts is interpreted as a value of 255

So if you divide 5 Volts by 256 possible steps (0-255 for 8-Bit resolution), the Reactor controller is sensitive to voltage changes as small as 0.0195 Volts.  A Reactor controller has 8 inputs.  Each input is capable of reading a separate voltage from 0 to 5 VDC, provided all voltages can share a common ground.  You configure exactly what value you want the board to trigger the relay or start a sequence or delay!

---

Trigger Logic

Reactor compares every sensor reading against user-defined trigger conditions. Instead of simply detecting whether an input is ON or OFF, Reactor can evaluate whether a sensor value is above, below, within, or outside a specified range before taking action.

• Above a value
• Below a value
• Within a range
• Outside a range

By combining these trigger conditions with timers, rotation counters, and relay assignments, Reactor can respond to virtually any sensor condition you define.

---

Timers and Rotation Counters

Timers allow Reactor to delay relay activation, keep relays energized for a specific duration, or schedule actions after an event occurs. Up to eight independent timers can run simultaneously and may trigger additional events through Event Piping.

Rotation Counters provide an easy way to alternate equipment, step through relay sequences, or distribute operating hours across multiple devices. Up to four rotation counters can operate in the background, making Reactor ideal for applications such as alternating pumps, compressors, or fans.

---

Event Piping

Event Piping allows one automation event to trigger another, making it possible to build sophisticated control sequences without programming.

For example, an input can start a timer. When that timer expires, it can trigger a second timer, increment a rotation counter, or activate another event. By linking events together, Reactor can perform multi-step automation that would normally require a PLC or custom software.

Whether you're creating delayed actions, equipment sequencing, or layered automation routines, Event Piping gives Reactor the flexibility to handle surprisingly complex applications while remaining easy to configure through Base Station Software.

---

Local Decision Processing

Unlike PC-based automation systems, Reactor evaluates sensor inputs and executes relay logic directly on the controller.

Because all decision making occurs locally, relay response times remain consistent even when a computer is disconnected. This improves reliability by eliminating the need for a continuously running PC, operating system updates, or background software during normal operation.

---

Deterministic Operation

Once configured, Reactor performs the same programmed logic every time the specified input conditions occur. Since all automation executes on the controller itself, operation is predictable and repeatable without relying on Windows, background software, or network communications.

---

Computer Override

Reactor gives you the best of both worlds. It can operate independently using its onboard decision logic, or a connected computer can temporarily take control whenever manual operation, testing, or monitoring is required.

When a computer issues relay commands, those commands take priority over Reactor's autonomous logic. Individual relays can be configured to remain under Reactor control while others respond directly to the computer, providing exceptional flexibility for hybrid automation systems.

Reactor Board Features

"Designed for reliable automation - the hardware makes it happen"

Reactor Relay

In this tab we'll take a look at the Reactor board design itself.  The Reactor series controllers are machine manufactured for a highly accurate and reliable design.  Fully tested before they leave the production facility each Reactor controller is ready to stand up to rigorous demands from heat, cold or vibration.  The best test of all is the numerous boards in the field from customers all over the world in all sorts of conditions.  Take it from us, these controllers will hold up!

---

---

The Input Side

"Where Reactor gathers information."

Configure with USB. Operate Automatically

This controller includes eight channels of 8-bit sensor inputs capable of reading 0 - 5V DC signals. The inputs allow you to monitor external sensors or detect contact-closure inputs. Connect temperature sensors, light sensors, current sensors, buttons, switches, or any device that outputs a 0 - 5V signal or simple contact closure.

8 Analog Inputs

• 0-5VDC
• 8-bit (256 levels)
• Sensor or contact closure
• Common ground
• Constantly monitored

Analog Resolution

Every analog input can distinguish 256 different voltage levels, allowing Reactor to make decisions based on precise sensor values rather than simple ON/OFF signals.

---

---

The Output Side

"Where Reactor controls your equipment."

SPDT Relay Installed

SPDT (Single Pole Double Throw) relays include three terminals: Common (COM), Normally Open (NO), and Normally Closed (NC)

• When the relay is off, COM is connected to NC.
• When the relay is energized, COM switches to NO.

Your load can be wired to either the NO or NC terminal depending on whether you want the device to turn on when the relay activates or when it releases. Examples of wiring methods can be found in the gray Relay Logic tab.

---

2 Million+ Cycles

Reactor relays are built for longevity - expect years of reliable operation and millions of mechanical cycles. Every board ships with a 5-year warranty and 30-day money-back guarantee.

---

---

Board Features

"What sets Reactor apart."

Break-A-Way Tabs for a Smaller Design

Need a smaller footprint? The Reactor PCB includes Break-A-Way Tabs, allowing the board to fit into optional undrilled enclosures or tight-space installations.

---

RoHS Compliant & Lead-Free

All ProXR Lite controllers are built with RoHS-compliant components and lead-free solder.

---

5-Yeary Warranty & Guarantee

Every Reactor controller is covered by:

• 5-Year Functional Warranty
• 30-Day Money-Back Guarantee
• No Monthly Subscriptions

If you're not satisfied, send it back for a refund within 30 days. (Damage caused after delivery isn't covered.)

---

Essential Power Requirements

Clean, regulated power is critical.
A stable 12VDC supply ensures both the relay coils and onboard firmware operate correctly. Unstable or noisy power can cause improper switching or communication issues.
We recommend the PWR12-US (120VAC → 12VDC @ 1.25A) or our international supply with interchangeable adapters.
Learn More

---

Shipping

All boards ship directly from our Missouri facility. Each unit is built and tested at the time of order - please allow 3 - 5 days for production. We ship primarily through UPS, but we're happy to use FedEx or DHL for international orders when you provide your account number. Questions? Call us at 800-960-4287 or email sales@relaypros.com.

---

Induction Suppression

One of the most important parts of relay control - yet the most commonly overlooked - is inductive load protection.

Anything with a magnetic coil (motors, solenoids, transformers, etc.) generates high-voltage "kickback" when switched. Without a suppression capacitor, that spike can:

• Shorten relay lifespan
• Cause electrical noise that disrupts the microcontroller
• Trigger unexpected shutdowns
• Require power cycling to restore communication

Adding an induction suppression capacitor protects your relay contacts and keeps everything running smoothly. Capacitors are available at checkout, and our Induction Suppression Page has wiring diagrams and more details.

---

Hardware Built for Automation

Trigger relays with a sensor with and configure with included Base Station software.  Here's a lists of great features:

User Friendly Software
• Point & Click Interface - No Programming Knowledge Required
• Override Sensor When Computer is Connected to Board
• Read Sensor Levels in Base Station
• Read Status of Relays in Base Station

User Friendly Board Design
• 8 Analog Sensor Inputs Available (0 to 5 Volt Only)
• Break-A-Way Tabs lets you decide the board's size
• Screw terminal connections make connecting to the relays easy

Power & More

"Reliable Power = Reliable Switching"

Board Performance Ratings

This tab brings together the essential performance ratings you'll want to know for NCD SPDT Relay Controllers and their supported communication modules. You'll find practical electrical requirements, power consumption estimates, operating limits, relay timing details, and more-all based on typical 12VDC operation at 70°F (21°C). Think of it as a reliable snapshot of how our hardware behaves under real-world conditions. Because every installation is unique, some values are estimates and may evolve as designs and testing continue. Use this information as a planning tool to help you choose the right controller, build an accurate power budget, and understand the capabilities built into every NCD SPDT relay board.

---

Powering from a Battery or Solar Panel?

NCD relay controllers are well-suited for battery-powered and solar-charged applications when operated within the recommended 10 - 15VDC range. This makes them ideal for remote, mobile, and off-grid installations using common 12V battery systems with solar charging. The power consumption data on this page helps you estimate runtime, size your battery, and avoid over-discharge. Staying within the voltage limits ensures stable, reliable operation in long-term battery and solar-powered setups.

---

The SPDT Relay

SPDT (Single Pole Double Throw) relays include three terminals: Common (COM), Normally Open (NO), and Normally Closed (NC)

• When the relay is off, COM is connected to NC.
• When the relay is energized, COM switches to NO.

Your load can be wired to either the NO or NC terminal depending on whether you want the device to turn on when the relay activates or when it releases. Examples of wiring methods can be found in the gray Relay Logic tab.

---

2 Million+ Cycles

ProXR relays are built for longevity - expect years of reliable operation. The SPDT relay is rated for millions of mechanical cycles. Every board ships with a 5-year warranty and 30-day money-back guarantee.

---

---

SPDT Relay Board

SPDT Relay Controller Specifications

This table outlines key performance ratings for all NCD SPDT Relay Controllers, based on 12VDC operation at 70°F (21°C). Many values are estimated and may be updated over time. Some ratings reflect standard, out-of-the-box settings without performance optimizations applied.

Processing times can vary depending on background services and the commands you use. Standby power values assume no communication module is installed and no relays are active. For a more accurate power estimate, be sure to include the consumption of any installed communications module and any energized relays.

SPDT Relay Specs

Specs of NCD SPDT Relay Boards	Minimum	Nominal	Maximum	Notes
Operational Voltages	10VDC	12VDC	15VDC
Standby Power Consumption	35mA	100mA	200mA	No Active Relays, No Com Module
Relay Power Consumption	28mA	35mA	60mA	Consumption of Each Activated Relay
Operational Temperature Range	-40°F (-40°C)	70°F (21°C)	185°F (85°C)	Theoretical Component Limits Shown
Storage Temperature Range	-67°F (-55°C)	70°F (21°C)	185°F (85°C)	Theoretical Component Limits Shown
Operational Ambient Air Humidity	0%	50%	70%	Non-Condensing Humidity Values Shown
Relay Activation Time	4ms	5ms	10ms	Needs Further Validation
Relay Deactivation Time	5mS	10mS	15mS	Needs Further Validation

---

---

Communication Modules

Communication Module Specifications

This table provides a quick, clear overview of all NCD Communication Modules. While each module operates at 3.3VDC, the values shown here reflect the impact on a 12VDC master controller at 70°F (21°C). Use the maximum ratings for power-budget planning - they represent short-term peak consumption and may include estimated values that are updated as modules evolve.

Communication Module Power Consumption

Specs of NCD Communication Modules	Minimum	Nominal	Maximum	Notes
Operational Temperature Range	-40°F (-40°C)	70°F (21°C)	185°F (85°C)	Theoretical Component Limits Shown
Storage Temperature Range	-67°F (-55°C)	70°F (21°C)	185°F (85°C)	Theoretical Component Limits Shown
Operational Ambient Air Humidity	0%	50%	70%	Non-Condensing Humidity Values Shown
USB Module Power Consumption	N/A	N/A	N/A	USB Modules are Powered by the USB Port Do Not Consume Device Current
RS-232 Module Power Consumption		10mA	20mA
Ethernet Module Power Consumption	58mA	82mA	100mA
WiFi Bluetooth USB Module Power Consumption	37mA	50mA	100mA	Up to 300 Foot Indoor Wireless Range, Unobstructed. Up to 50 Foot Range Through Walls
900MHz Wireless Module Power Consumption	13mA	30mA	50mA	Up to 1,000 Foot Indoor Wireless Range, up to 2 Mile Outdoor Wireless Range using Included Antennas. Up to 28 Miles Outdoor Wireless Range using High-Gain Antennas.
KFX Wireless Key Fob	11mA	15mA	25mA	Up to 200 Feet Outdoor Wireless Range using 1, 2, 3, 4, or 5 Button Key Fobs. Up to 700 Feet Outdoor Wireless Range using 8-Button Remotes

---

---

A/D Inputs

AD8 Analog Input Usage Notice

Analog inputs should never have voltage applied when the controller is powered down. If your application requires voltage to remain on an input, add a 220-ohm current-limiting resistor to each channel to protect the controller from damage. Keep all analog inputs within the 0 - 5VDC range - exceeding this limit can permanently damage the on-board CPU. Most inputs include a 10K pull-up or pull-down resistor to keep the line stable when unused, but note that this resistor may introduce a slight bias in readings for certain sensors.

LRR410_USB Accessories

Relay Logic

"Using a light as an example load, let's wire to the board"

Relay Wiring Samples

This page provides simple examples showing how to wire a single relay - or multiple relays - for common switching applications. We use a light as the example load, but you can substitute a gate controller, security panel input, dry contact device, motor trigger, or most other switched loads. These wiring samples demonstrate different ways to connect relays to achieve the switching behavior you need.

Get a printout of this page

---

---

Relay Types

SPDT Relay

SPDT (Single Pole Double Throw) relays include three terminals: Common (COM), Normally Open (NO), and Normally Closed (NC).

• When the relay is off, COM is connected to NC.
• When the relay is energized, COM switches to NO.

Your load can be wired to either the NO or NC terminal depending on whether you want the device to turn on when the relay activates or when it releases. Examples below demonstrate both wiring methods. The SPDT relays offered on this site are 5-Amp, 10-Amp and 20-Amp models.

---

SPST Relay

SPST (Single Pole Single Throw) relays provide two terminals: Common (COM) and Normally Open (NO).

When the relay coil is energized, COM connects to NO to power the load. The only SPST relays offered on this site are our 30-Amp models. All SPDT examples shown on this page apply to these relays as long as the example does not require a Normally Closed terminal.

---

DPDT Relay

A DPDT (Double Pole Double Throw) relay contains two SPDT switches that operate together.

• Each side includes its own COM, NO, and NC terminals.
• Both internal switches change state at the same time.

This allows you to control two independent circuits with one relay. Wiring for each side of a DPDT relay follows the same rules as an SPDT relay, so the examples on this page apply directly. We offer the DPDT relays in 1-Amp, 3-Amp and 5-Amp models on ProXR boards starting at 8 relays.

---

---

Relay Logic Examples

Example 1 - Simple Off/On Control

This example shows the most basic way to use a relay to switch a device such as a light. When the relay energizes, its NO (Normally Open) contact closes to COM (Common), completing the circuit and turning the light on.

Only a single power wire is switched in this setup, making it the simplest method for controlling a light - or any device - using a relay.

Use this example for switching a light or any device you want to power only when the relay is on.

---

Example 2 - Simple On/Off (Using NC Contact)

This wiring method keeps the light on by default. The relay switches a single power wire through the COM (Common) and NC (Normally Closed) terminals.
When the relay is not energized, the NC contact is closed to COM and the light remains on.
When the relay energizes, the NC contact opens, interrupting power and turning the light off.

This approach is ideal for devices that stay on most of the time, reducing relay wear since it doesn't need to remain energized to keep the device powered. It's also a useful method for power-cycling equipment - energizing the relay momentarily will turn the device off.

---

Example 3 - AND Logic Using Two Relays

This example shows how two relays can work together so a light turns on only when both relays are energized. This creates an AND Logic condition:
Relay 1 AND Relay 2 must be on for the light to receive power.

A single power wire is switched, but it must pass through both relay contacts before reaching the light. This setup is ideal when two conditions must be met at the same time - such as requiring input from multiple sensors or system parameters.

---

Example 4 - AND Logic Using Three Relays

This example expands on the previous AND Logic concept. Here, the light will turn on only when all three relays are energized:

Relay 1 AND Relay 2 AND Relay 3 must be on for power to reach the light.

A single power wire is routed through all three relay contacts. Wiring from the NO (Normally Open) of Relay 1 to the COM (Common) of Relay 2, then from the NO of Relay 2 to the COM of Relay 3, creates a series path that requires every relay to energize before the light can activate.

This method can be scaled easily - just continue wiring NO of each relay to the COM of the next relay. Add as many relays as needed to meet your logic or safety requirements.

---

Example 5 - AND/OR Logic with Override

This example demonstrates a combined AND/OR logic setup. The light will turn on when:

• Relay 1 AND Relay 2 are both energized
  OR
Relay 3 is energized (override)

This wiring is useful when you need a normal logic condition plus a manual or automatic override option.

For example:
• Relay 1 = night/day sensor
• Relay 2 = motion sensor
• Relay 3 = manual override (local switch)

If it's dark and the motion sensor activates, Relays 1 and 2 energize to turn on the light. But if you want to control the light manually - regardless of sensor conditions - Relay 3 can override the logic and activate the light on its own.

---

Example 6 - OR Logic (Either Relay Activates)

This example demonstrates OR Logic - the light will turn on when either relay is energized. Only one power wire is switched, but it can pass through Relay 1 or Relay 2 to reach the light.

• If Relay 1 activates, the light turns on
• If Relay 2 activates, the light turns on
• If both activate, the light remains on

This setup is ideal when two independent sources should be able to control the same device. Common uses include:

• A timer controlling one relay, with a manual or secondary control for the other.
• Two sensors where either condition (motion detected or low light, for example) should activate the light.

---

Example 7 - 3-Way Switch (Relay-Based 3-Way Control)

This example shows how to create a 3-way light switch setup using relays. A traditional 3-way circuit allows two switches to control the same light from different locations. In this wiring sample, each physical switch is replaced by a relay - but the operation is the same.

Only one power wire is switched, and the relays toggle the light depending on their current state.

• Activating either relay will toggle the light
• Activating both relays at the same time has the same effect as flipping both switches at once

This wiring method is especially useful because you can replace one of the relays with a physical light switch, giving you both computer control and manual control of the same light. When used correctly, this becomes one of the most flexible and powerful diagrams on the page.

---

Example 8 - DC Motor Direction Control

This example demonstrates how to control the direction of a DC motor using two relays. By changing how the motor's leads connect to power, you can run the motor forward, reverse, or place it in a brake state. Braking is achieved by tying both motor terminals to the same power connection, which stops rotation through Faraday's Law.

Relay Operation Summary

• Relay 1 Off / Relay 2 Off → Motor Brake to +
• Relay 1 On / Relay 2 Off → Motor Forward
• Relay 1 Off / Relay 2 On → Motor Reverse
• Relay 1 On / Relay 2 On → Motor Brake to -

The capacitors shown are optional for small motors, but may be required in some situations:

• The induction suppression capacitor prevents the relay from shutting off due to motor back-EMF
• The 0.1µF filter capacitor reduces electrical noise, especially useful when powering sensitive electronics such as radios or amplifiers.

Capacitor Placement
• Place the induction suppression capacitor near the relays
• Place the filter capacitor near the motor
• Additional capacitors may be needed for certain motors

Important Note on Inductive Loads
Motors draw significantly more current at startup than during continuous operation - often 2-3 times their rated running current. For example, a motor rated at 5A (125VAC) may require 10-15A to begin turning. Always select a relay that exceeds the motor's initial inrush current, not just its running current. In this case, a 20-30A relay provides optimal performance and longevity.

Data Sheets & Quick Start Guides

Below are the Data Sheets Quick Start Guides for this board.  These are the guides that will help you communicate and configure this board.