Mitsubishi AL2-14MR-D Alpha 2 Logic Module 24VDC

MITSUBISHI AL2-14MR-D ALPHA 2 LOGIC MODULE 24VDC

The Mitsubishi AL2-14MR-D (Alpha 2 Series) is a self-contained, micro-programmable logic controller engineered for dedicated machine control, process sequencing, and distributed auxiliary systems. Operating on a 24V DC nominal power bus (19.2V to 30.0V DC operational envelope), this controller integrates 8 digital inputs (all 8 reconfigurable as 0–10V DC analog inputs) and 6 electromechanical relay outputs within a rugged, DIN-rail mount housing.

In shipboard environments characterized by heavy vibration, ambient temperature shifts, and volatile auxiliary electrical grids, standard commercial logic relays frequently suffer processor lockup or premature contact degradation. The AL2-14MR-D meets strict industrial noise-immunity benchmarks and holds DNV Type Approval, making it an operational standard for maritime machinery spaces, emergency generator synchronization interlocks, oily water separator (OWS) discharge control, and engine room ventilation dampers.

Model Details

• Manufacturer: Mitsubishi Electric
• Product Series: MELSEC Alpha 2 (α2) Series
• Model: AL2-14MR-D
• Manufacturer Part Number (MPN): AL2-14MR-D
• Internal / Catalog Order Code: 142537 / AL214MRD
• HMI / Display: Integrated 12-character x 4-line LCD with 8 operating/navigation pushbuttons

Technical Specifications

Features

1. High-Density Hybrid Input Architecture: Equipped with 8 multi-function DC inputs (I01–I08); all 8 channels accept standard 24V DC sink/source digital switching or 0–10V analog signals with 9-bit resolution.
2. High-Capacity Isolated Relay Outputs: Features 6 independent Form-A (Normally Open) relay contacts rated at 8A resistive / 2A inductive per channel at 250V AC or 30V DC, eliminating the need for interposing relays on small motors, solenoids, or contactors.
3. Integrated Operator Interface & Real-Time Clock (RTC): Built-in front-panel backlit display allows direct variable adjustment, analog process variable reading, customized text-alarm annunciations, and calendar/time-based scheduled automation routines without connecting a PC.
4. Non-Volatile Flash Program Storage: Retains up to 200 Function Blocks (5 KB internal EEPROM capacity) and non-volatile data registers indefinitely without requiring a continuous battery backup.
5. Marine & Industrial Class Reliability: Fully certified to maritime classification requirements (DNV) with superior electrostatic discharge (ESD), surge suppression, and shock/vibration tolerance across an operating envelope of -10°C to +55°C.

Compatible Extension Modules & Accessories

• Expansion I/O Boards: AL2-4EX (4 Digital Inputs 24V DC), AL2-4EYR (4 Relay Outputs), AL2-4EYT (4 Transistor Outputs).
• Analog & Temperature Adapters: AL2-2PT-ADP (Dual PT100 RTD interface), AL2-2TC-ADP (Type K Thermocouple interface), AL2-2DA (2-channel 0–10V / 4–20mA Analog Output).
• Communication Modules: AL2-ASI-BD (AS-Interface Actuator Sensor Interface), AL2-GSM-BD (GSM SMS/modem reporting card).
• Programming Cables & Memory: AL-232CAB (RS-232 Serial Programming Cable), USB-SC09 / AL2-USB-CAB (PC-to-Alpha USB Interface), AL2-EEPROM-2 (External Memory Cassette).
• Engineering Software: AL-PCS/WIN-E (Mitsubishi Alpha Programming Software suite, compatible with Windows XP through Windows 11 64-bit using dedicated serial/USB drivers).

Part Number Cross-References

• Direct Order MPN: AL2-14MR-D
• Factory Item Code: 142537
• ERP / Alternate Part String: AL214MRD, AL2 14MR D
• Legacy Generation Predecessor: AL-14MR-D (Alpha 1 Series – Note: Ensure program conversion via AL-PCS/WIN before swapping, as function block mapping differs).

Frequently Asked Questions

Can I program the Mitsubishi AL2-14MR-D directly from the front panel without software?

Yes. The front panel features a backlit 4-line LCD and 8 navigation keys that permit complete Function Block Diagram (FBD) programming, timing parameter editing, and direct force run/stop operations. However, for complex shipboard automation routines involving up to 200 function blocks, programming via AL-PCS/WIN-E software with an AL-232CAB or AL2-USB-CAB programming cable is significantly faster and allows program archiving.

How do I use the inputs for 4–20mA process instruments instead of 0–10V?

The AL2-14MR-D natively accepts 0–10V DC analog signals on inputs I01 through I08. To interface standard marine 4–20mA process loops, terminate a precision 500Ω (0.1% tolerance, 0.5W) resistor across the chosen input terminal and the common 0V [-] DC rail. The 4–20mA loop current creates a 2V to 10V drop across the resistor, representing an internal software scale of 100 to 500 counts.

Can the AL2-14MR-D directly replace an older Alpha 1 AL-14MR-D unit?

Yes, physically and electrically the AL2-14MR-D fits into the identical 35mm DIN-rail footprint and uses the same 24V DC terminal configuration. However, because the Alpha 2 architecture supports advanced function blocks and higher processing speeds, existing Alpha 1 programs must be opened and recompiled in the AL-PCS/WIN software before transferring to the AL2-14MR-D.

What is the advantage of using relay outputs (MR) versus transistor outputs (MT)?

The AL2-14MR-D features isolated electromechanical dry relay contacts rated up to 8A at 250V AC / 30V DC. This allows mixed-voltage switching (e.g., controlling a 115V AC alarm klaxon on one channel and a 24V DC fuel solenoid on another) directly from the PLC without needing secondary interposing interface relays, saving enclosure space and wiring complexity.

What happens to the program during a total shipboard blackout?

The program logic and parameter settings are written directly to internal non-volatile EEPROM memory blocks, ensuring that the control code is maintained indefinitely without battery dependence. An onboard supercapacitor retains the Real-Time Clock (RTC) date and time for up to 20 days across unpowered blackout conditions.