MirM Wireless

"If your alternative involves drilling under a road...
it might be time to go wireless."

Wireless Relay Control - Across Multiple Locations

The MIRMR15 lets you control relays in multiple locations from a single dry contact input - no trenching, no conduit, no complicated wiring between buildings.

Close the contact → All remote relays energize
Open the contact → All relays turn off

Simple, reliable control - expanded across as many locations as you need.

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Stop Running Wires

Trigger lighting across several buildings, activate multiple systems at once, or coordinate equipment across a wide area - all from a single switch - without installing long cable runs!

If running wires to one location is hard, running them to many is even harder. MirM solves that wirelessly.

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Reliable Wireless Communication

MirM boards use 900MHz 900HP modules paired by unique serial numbers, allowing one sender to communicate with multiple receivers for dependable multi-point operation.

With clear line-of-sight, systems can reach distances up to 2 miles (3.2 km), making them ideal for campuses, large properties, and distributed equipment setups.

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It worked on my bench... why not through two buildings and a metal wall??

MirM wireless range is based on clear line-of-sight between the antennas. While these 900 MHz radios support up to a 2-mile line-of-sight range, walls, buildings, trees, terrain, and especially metal can significantly reduce - or completely block - wireless communication.

Upgrading to a higher-power radio will not magically punch through obstructions.
Clear line-of-sight always wins.

The good news is that in many real-world installations, you can usually find a reliable "sweet spot" by using antenna extension cables to relocate one or both antennas. Even small changes in antenna placement or height can make a big difference when the radios can better "see" each other.

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Flexible Installation

Need better signal positioning? An optional extension cable (up to 20 ft / 6 m) allows you to relocate the antenna for improved line-of-sight. Uses standard RP-SMA (Reverse Polarity SMA) connections.

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What Happens When Communication is Lost

If a relay is energized and the connection drops between the remote boards, you get to choose what happens next:

• The relays can stay energized until communication returns (Beacon Mode)
or
• The relays can turn off automatically (Smart Mode)

Just set the jumper for Beacon or Smart mode depending on how you want the system to behave.

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Multiple MirM Pairs, No Cross-Talk

Yep - multiple MirM sets can operate within range of each other. Each set is matched by the serial numbers of the radios installed, so they won't step on each other's signals.

However, if a large number of devices all share the same channel, you may see interference or dropped communications. There are several ways to manage that, so if you're planning a large deployment, reach out - we're happy to help with best-practices.

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Who’s Qualified to Use the MirM Series?

Honestly? Pretty much anyone.
MirM controllers are extremely user-friendly: the wireless pairing is handled in before shipping, and the wiring is straightforward. Whether you're an engineer or a weekend tinkerer, MirM boards are designed to be approachable and dependable.

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Step-by-Step Connection Guide

1. Connect Your Device:
• Wire the contact closure output of your device to the input terminals on the Sender Board
2. Power Both Boards:
• Apply 12VDC Power to both the Sender and Receiver Boards
3. Wireless Linking:
• The 900HP wireless modules automatically establish the communication link (no configuration required in standard MirC wireless systems)
4. Use the Relay Output:
• Wire the relay contacts on the Receiver Board to the circuit or equipment you want to control at the remote location. Wiring examples can be found in the Relay Logic tab.
5. Trigger the Closure:
• When the contact closure activates at the Sender Board, the Receiver Board's relay mirrors that state almost instantly

MirM Board Features

MirM Relay

MirM controllers are a point to Multi-point set of boards that allow you to control relays by using a contact closure (no voltage).  Inputs on the sender board controls relays on multiple remote boards.  The relays will remain energized as long as the contact closure input is closed, when the input opens the relay will turn off.  Depending on the contact closure input that you are using you can momentarily keep the relay on or use an toggle switch can trigger relay on then off.  The relays provide no voltage and can be used as a dry contact output if needed.

Sender Boards

The MirM sender board is basically a contact closure (no voltage) input board.  The board will have as many inputs as there are relays on the receiver board.  The inputs will control the relays on the receiver boards.  Input 1 will control all relay 1's on the receiver boards.  Input will control all the relay 2's and so on. 

No Voltage Inputs

Contact closure inputs such as buttons, switches or other electronic devices (no voltage) attached to inputs on the sender board will trigger relays on the remote locations.  The Sender has inputs while the Receivers have relays.  When an input on the Sender is tripped by a contact closure a relay on a Receiver board is energized and will remain energized until the contact closure is released. 

Receiver Boards

The sender board can communicate wirelessly to Receiver Boards.  These locations will have to be in range of the sender board which can be up to 2 miles (3.2km) line-of-sight.  The remote locations will receive a command from the sender board when a contact closure input that is associated with the board is closed to energize a relay or a group of relays in different locations.  When the Contact Closure circuit opens the associated relays will de-energize or turn off.  Additional remote locations can be added at a later date but all married boards in the system will need to be sent back for configuration.

2-Million Cycles

MirW series controllers are designed for long life, you should expect to get years of service from your controller and literally 2-million cycles from the relays on board.  With a 5-year warranty and a money back guarantee you have nothing to loose!  Place your order now, while everything is in front of you.

SPDT Relay Installed

The Receiver Board has SPDT relays installed.  SPDT Single Pole Double Throw Relays have three connections - Common, Normally Open, and Normally Closed.  When the relay is off, the common is connected to the normally closed connection of the relay.  When the relay coil is energized, the Common swings over to the Normally Open Connection of the Relay.  You can wire the device you are switching to either the Normally Open or the Normally Closed position using screw terminal connections.  The maximum guage wire the terminal can handle is 14 ga but we have used up to 12 ga solid core for several applications with no issues.

Break-A-Way Tabs for a Smaller Design

The MirW sender boards have a great feature where space is a premium - Break-A-Way Tabs!  The Break-A-Way Tabs allow most boards to fit in an optional undrilled plastic enclosure.  Snap off the Break-A-Way Tabs and you have a board with a smaller profile when you need to fit in a tight space.

5-Year Warranty/Money Back Guarantee

MirW controllers are guaranteed against manufacturing and functionality defects for a full 5 years!  Not to mention a 30-day money back guarantee!  If for any reason you are not happy with a relay purchased from Relay Pros, simply return it within 30 days and we will give you your money back!  Controllers that are damaged by our customers will not of course be warranted under any circumstances. 

This Board is RoHS Compliant

This board is led free and RoHS Compliant.  If your requirements are for RoHS compliant parts this board is manufactured with RoHS compliant led free parts and solder.

Shipping

The boards sold are brand new units shipped from our manufacturing facility conveniently located in Missouri.  These boards are completely tested before they are released for shipping  With so many boards on our site it is impossible to stock boards, please allow 5 to 7 days production time for your order to ship.

Who’s Qualified to Use the MirM Series?

Anyone!  The MirM Series Controllers are very consumer-friendly devices that are married together through software and only require some wiring by the end user.  Whether an electronics engineer or a home hobbyist, almost anyone is qualified to use the MirM Series controllers. 

Induction Capacitors

Perhaps the most overlooked aspect of relay control is proper handling of inductive loads.  Inductive loads are anything with a magnetic coil, such as a motor, solenoid, or a transformer.  Controlling a inductive load using these boards requires induction suppression capacitors to absorb the high voltages generated by inductive loads, blocking them from the contacts of the relay.  Without this capacitor, the lifespan of the relay will be greatly reduced.  Induction can electrically interfere with the microprocessor logic of the boards, causing relay banks to shut down unexpectedly.  If this happens the boards may need to be power cycled to restore communication.  Capacitors are available at checkout, for more information and drawings view our Induction Suppression Page.

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.

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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.

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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.

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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.

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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

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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

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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.

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

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

A/D Board Users: The Relay Activator function on any A/D board or ProXR Lite board lets you connect a button or switch to any A/D input. This input can then control the override relay, giving you a convenient local button to manually override the first two relays.

MirC/MirX Users: Add a manual button or switch to trigger the third relay when you need direct control instead of sensor-driven control.

Reactor Users: A local button or switch can be wired to the third relay input to provide a manual override for sensor-based logic.

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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.

A/D Board Users: The Relay Activator function on any A/D board or ProXR Lite board lets you connect a button or switch to any A/D input. This input can then be used as a manual control of the relay.

MirC/MirX Users: Wire two contact closure inputs into the sender board - either input can trigger the receiver relay to control the light.

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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.

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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