Automated Logic ME812u-E Multi-Equipment BACnet Controller

Automated Logic ME812u-E ME-Line Multi-Equipment General Purpose Controller

The Automated Logic ME812u-E is a Direct Digital Controller (DDC) engineered for complex, multi-equipment plant and central HVAC applications. Designed under the flagship ME-Line architecture, the ME812u-E provides native high-speed BACnet over Ethernet / BACnet/IP connectivity, eliminating bottlenecks in supervisory network communications.

Equipped with 20 onboard physical I/O channels (12 Universal Inputs and 8 Universal Outputs) and expandable up to 164 total points via the proprietary CAN-bus-driven Xnet communication bus, the ME812u-E delivers exceptional distributed processing power. Its ruggedized, extruded aluminum chassis, combined with comprehensive onboard transient surge protection, makes it equally reliable for critical commercial facilities, offshore accommodations, and marine machinery-space environmental automation.

Model Details

• Brand: Automated Logic Corporation (ALC)
• Product Line: ME-Line (Multi-Equipment Series)
• Model: ME812u-E
• Manufacturer Part Number (MPN): ME812u-E
• OEM Cross-References: OEMCtrl I/O Pro 812u-E series equivalents

Technical Specifications

Key Features

1. High-Density Hybrid I/O with Local Manual Overrides: Features 12 Universal Inputs (14-bit resolution) and 8 Universal Outputs (12-bit resolution) with integral Hand-Off-Auto (HOA) toggle switches and manual potentiometers for analog calibration and fail-safe commissioning.
2. High-Speed BACnet Connectivity: Native 10/100 Mbps Ethernet port directly supporting BACnet/IP and BACnet over Ethernet, ensuring high-speed integration into WebCTRL® and third-party Building Automation Systems.
3. Modular Xnet Expansion Bus: Connects up to six MEx expansion modules via high-speed 500 Kbps CAN bus, allowing expansion up to 164 I/O points either stacked directly on the controller or distributed up to 100 feet away.
4. Robust Hardware & Processing Architecture: Powered by a 32-bit Motorola PowerPC CPU with dedicated communication and CAN co-processors, 8 MB Flash, and 16 MB battery-backed SDRAM for long-term onboard data trending and fault diagnostic logging.
5. Industrial & Marine-Grade Reliability: Heavy-gauge aluminum construction with integrated circuit surge/transient suppression across power supply, communication buses, and terminal blocks.

Equipment Compatibility

• Automated Logic WebCTRL Systems: Fully integrated with WebCTRL v3.0 through current software revisions.
• MEx I/O Expander Modules: Fully compatible with MEx816u, MEx48u, MEx88u, and legacy MX expanders via 9-pin sub-D adapters.
• Local Displays & Room Sensors: Direct connection to Rnet ports supporting ALC RS-Standard, RS-Plus, RS-Pro, ZS-series room sensors, and BACview5 / BACview6 / Equipment Touch interfaces.
• Subsystem Integration: Capable of controlling multi-stage centrifugal and screw chillers, multi-zone Air Handling Units (AHUs), dual-duct systems, cooling towers, and boiler sequencing skids.

Applications

• Central Plant Automation: Sequence logic for chillers, secondary chilled water pumps, heat recovery loops, and condenser water balancing.
• Complex Air Handling Units: Mixed-air variable air volume (VAV) handling systems, energy recovery wheels (ERVs), face-and-bypass damper loops, and multi-stage heating/cooling coils.
• Marine & Offshore Facilities: Living quarter HVAC control, wheelhouse positive pressurization control, machinery space ventilation damper logic, and marine chilled water central loops.
• Cleanrooms & Laboratories: Multi-variable differential static pressure tracking, precision humidity dehumidification/reheat sequencing.

Frequently Asked Questions

What is the primary difference between the ME812u and the ME812u-E?

The standard ME812u utilizes an RS-485 serial communication port configured for BACnet MS/TP or ARCNET (156 kbps), whereas the ME812u-E is specifically engineered with an onboard 10/100 Mbps Ethernet port dedicated to high-speed BACnet over Ethernet or BACnet/IP network backbones.

Can I expand the I/O capacity if my air handling unit has more than 20 points?

Yes. The ME812u-E includes an Xnet communication port running at 500 Kbps. You can attach up to six MEx expansion modules (such as the MEx816u or MEx48u), expanding system capacity up to 164 total hardware points. The first expander can mount directly on top of the ME812u-E chassis, or modules can be mounted remotely up to 100 feet away.

How do the Hand-Off-Auto (HOA) switches operate on the Universal Outputs?

Each of the 8 universal outputs features a 3-position toggle switch (Hand, Off, Auto) and an adjustment potentiometer. In “Auto”, the DDC algorithm dictates output state. In “Off”, the output is forced de-energized. In “Hand”, digital outputs are forced to 24 VDC, and analog outputs are manually controlled via the potentiometer (0–10V or 0–20mA), allowing manual plant operation during maintenance.

How long does the internal backup battery last, and what does it preserve?

The onboard 3V CR123A lithium battery has a nominal shelf life of up to 10 years and provides up to 720 hours of cumulative backup for the real-time clock and dynamic trend/alarm data stored in the 16 MB SDRAM during main power interruptions. The core operating application is stored in permanent Flash memory and will not be lost if the battery fails.

Can the ME812u-E read RTD and Thermistor temperature sensors directly without external transmitters?

Yes. The 12 universal inputs feature high-resolution 14-bit analog-to-digital converters supporting direct termination of 10k Type II thermistors as well as 1k Ohm Platinum, Nickel, or Balco RTDs without requiring signal conditioning transmitters.