Off-The-Shelf Control Systems

Our line of “Off The Shelf” controllers for M&M Refrigeration are designed to offer the same energy saving features found in our larger custom control systems. These products are user configurable to meet the needs of small to medium sized facilities. These “Off The Shelf” control systems or OTCS products are intended to allow a facility operator to control their refrigeration equipment and energy usage with a minimal initial investment.

  • Common Functionality and Features
  • Common Scalable Hardware and Software Platform
  • Utilizes the Software Approach Found in Our Customized Control Systems
  • User Configurable to Meet a Specific Facility’s Requirements
  • Targeted System Controls with Energy Saving Features
  • Can Be Integrated Into Larger Customized Control Systems

Available Controllers

We currently offer several off the shelf controllers and are continuously developing new units with additional functions. A list of currently available units is as follows:

  • Master Screw Compressor Controller with Sequencing for up to 8 compressors
  • Condenser Control for up to 4 pumps and 8 fans
  • Sequencing and Condenser Controller
  • Evaporator Controller (4, 8, 12, 16 and 20 zone configurations)
  • Pump Package Controller
  • Split Package Control
  • Ice Rink Controller (single and dual rink)
  • Beer Distribution Warehouse Controller (CEW/Draft configurations)
  • Gas Detection Systems (GDS-8)

The Evaporator Controller is a microprocessor-based control system designed for efficient automatic control and monitoring of all evaporator zone functions.

The system is responsible for temperature control, scheduling and evaporator zone defrost. The system will automaticly monitor zone temperatures and control each zone independently to maintain setpoints based on an operator defined schedule.

Setpoints, evaporator operating modes, fan cycling method, scheduling of temperature setpoints, and defrost parameters can be changed by the operators to match the individual needs of the facility.

The Evaporator Controller can control different types of evaporators together as a system with multiple defrost types and valve stations. The system also provides for a defrost queue so the number of zones defrosting at one time can be limited.

A PC software option is available for remote monitoring of real-time data from the Evaporator Controller.

The PC can be connected through an RS-422 communications network for access to data, logs, reports and setpoints. Remote, off-site, access to the controller is available through a phone line when used with the modem option or an IP address with the Ethernet option.

The PC software provides for automatic downloading of all system data. This data can be used to generate graph plots and reports for detailed information on historical system performance.

The controller is a UL and cUL listed industrial control panel built to UL508A specifications.

Control Features

  • Support for all Valve Configurations and Defrost Methods
  • Real-Time, Easy-To-Read Display
  • Customizable User Defined Zone Names
  • Status & Diagnostic Screens on Evaporator Conditions
  • Customizable Ten (10) Level Password Security System
  • Comprehensive Alarm Reporting and Data Logging Function
  • Ability to Share Temperature Sensor with Different Zones
  • Extensive Set of Energy Management Features
  • User Programmable Defrost Queue Limits
  • Staging Control for Power Failure Recovery of Zones
  • Temperature Scheduling: 3 Schedules with 8 Event Times Each
  • Fan Cycling Options (Always On, Temperature, Anti-Stagnation)
  • Defrost Options: None, LFR, Scheduled or Demand
  • Support For Defrost Termination Input
  • Support for Liquid and Hot Gas King Valve Control
  • Manual Override Of Schedule Number And Setpoint Group
  • Support For Linking Multiple Controllers Together
  • Common Scalable Hardware and Software Platform


Microprocessor Board

  • 16 Channels of Analog Input (12-Bit, 4/20 mA, 0-5V)
  • 32 Channels of Discrete I/O (Expandable)
  • Two RS-422/RS-485 Communications Ports
  • Watchdog Timer and Self Test Functions
  • Battery Backed Memory and Power Monitoring Circuits

Display Adapter Board

  • Supports Multiple Font Sizes Including Reverse Video
  • Keypad Support and Digital Contrast Control


  • 120/240 VAC, 50/60 Hz, Single Phase Power Supply
  • Maximum FLA: 30 Amps
  • Internal Breakers: 1, 5 and 15 Amps

Modem/Communications Board

  • COM 2: RS-232/Modem
  • COM 3: RS-232/RS-422/RS-485
  • Protocols: PC Interface
  • Options: 56K Modem / Ethernet Board

I/O Board

  • 32 Channel Design with Optically Isolated Modules
  • Standard Layout: 27 Outputs and 5 Inputs
  • Nominal Voltage: 120/240 VAC
  • Max: 140/280 VAC/VDC
  • Min Voltage: 90/180 VAC/VDC
  • Max Load: 1.5A 120VAC (running), 30A 120VAC (inrush)


  • Enclosure: 60” H x 36” W x 8” D - NEMA 4 , UL Type 1
  • Keypad: Full Numerical with Dedicated Special Function Keys
  • Display: Graphical Backlit LCD, 10” Diagonal Size
  • Operating Temperature: -0°: +50°C
  • Storage Temperature: -10°: +85°C
  • UL File Listing: NITW.E136526
  • cUL File Listing: NITW7.E136526

M&M Systems produces a fully configurable Gas Detection, Monitoring and Reporting System; the GDS-8. The unit supports up to 8 analog gas concentration detectors (NH3, R22 or CO2) with programmable alarm and failure levels and discrete outputs for status or control. The unit is able to interface with a variety of manufacturer’s sensors. Extensive alarm reporting and data logging capabilities have been incorporated to provide post-failure data analysis and to aid in system diagnostics. The system supports the following configurations:

  • Detector-Only Configuration
  • Engine Room Temperature Control Configuration

The Detector-Only configuration provides inputs for up to 8 analog gas detectors. The Engine Room Temperature Control configuration replaces one gas detector with an engine room temperature sensor. It is used for monitoring and exhaust fan temperature control. Both configurations support summary control outputs, individual outputs for each detector, user-programmable exhaust fan control and two custom control outputs.

Hardware Overview

The GDS-8 maintenance and control system is housed in a waterproof, corrosion-resistant enclosure designed to NEMA-4 specifications. Inside the enclosure is a microprocessor based controller powered by an AC/DC universal input power supply. Connections to the unit are through the bottom of the enclosure and utilize waterproof connectors. The GDS-8 is designed for both outdoor and indoor industrial environments. The hardware requires no operator intervention in the event of a power failure. A local display, keypad and Light Emitting Diodes (LEDs) are provided for day-to-day operation. The LEDs are bright enough to allow a quick at-a-glance view of present and past system performance. The local display and keypad are useful for determining more detailed information such as the current status of all sensors or the time and date of past alarm events.

General Overview

The software is designed to monitor the gas detectors for the primary purpose of notifying plant personnel of a problem with the plant equipment before a failure occurs. Also included are various optional safety controls and monitoring points to improve system performance.

Some of the basic features of the GDS-8 include:

  • Fully Configurable, Reliable and Affordable
  • Supports Up To 8 Sensors Per Gas Detection System
  • User Configurable For Sensor Type, Range and Output Notification Level
  • Extremely Informative Logging System: Records All Sensor Values, Alarms and Failures
  • Can Link Multiple Detection Panels Together to Monitor up to 64 Sensors.
  • NEMA 4 Enclosure: 14”H x 14”W x 4”D
  • Password Protection and Tracking

Control Features

The system provides a full complement of software functions to allow each controller to be customized to meet facility requirements. An overview of the major control features provided by the GDS-8 is as follows:

  • Support For Many Different Gas Sensor Models
  • Numerous Sensor Ranges And Measurement Units
  • Programmable Alarm And Failure Levels For Each Sensor
  • Dedicated Indication Outputs For Each Sensor And High Visibility Front Panel LED Indicators
  • Audio/Visual Output Indicates Alarm/Failure On Any Sensor
  • Custom Outputs Configurable For Indication Or Control Based On Multiple Sensors
  • Alarm/Failure Inhibit Delay After Power Failure To Allow Sensor Warm-Up And Prevent False Indications
  • Comprehensive Data Logging System
  • Standard Exhaust Fan Control For A Single Unit With An Override Switch Input In The Base Unit
  • Optional Support For Exhaust Fan Temperature Control And The Addition Of A Second Exhaust Fan When The Unit Is Configured For Temperature Control.
  • AUX Inputs For All Exhaust Fans To Validate Operation
  • Gas Detection Override Is Configurable Per Sensor For Each Exhaust Fan Controlled By The System.
  • Built-In Support For ModBus RTU Protocol
  • Built-In Communications For Linking Up To 8 Controllers