Honeywell MasterLogic Modules: 2MLQ-SS2A-CC

Technical Dossier

Product Details And Specifications

Honeywell MasterLogic Series Technical Notes

The Evolution of MasterLogic Architecture

The MasterLogic platform was introduced by Honeywell as a mid-to-large scale PLC solution bridging the gap between the company's distributed control system (DCS) heritage—rooted in the TDC 3000 and Experion PKS lines—and standalone PLC deployments. Early MasterLogic hardware used proprietary backplane buses with fixed rack configurations. Subsequent generations introduced the modular Q-series rack system (MLQ prefix), enabling flexible slot allocation between CPU, I/O, and communication modules. The SS2A controller designation indicates a dual-port serial/network communication variant with enhanced scan-rate performance. Compatibility across MasterLogic generations is constrained by backplane bus revision: first-generation modules (ML-series) are not electrically compatible with second-generation Q-series (MLQ-series) racks without adapter hardware. As the platform has entered its mature/end-of-life phase, Honeywell's recommended migration path is toward the Safety Manager SC or ControlEdge PLC platforms; however, the installed base of MasterLogic systems remains substantial, and direct module replacement remains the preferred maintenance strategy for facilities not yet scheduled for full DCS migration.

MasterLogic Full Catalog & Functionalities (SKU List)

The following SKUs represent verified, commonly sourced modules within the Honeywell MasterLogic (MLQ) platform. Modules are classified by functional category.

CPU / Controller Modules

• 2MLQ-SS2A-CC: Dual-port serial CPU module, standard scan, Q-series rack
• 2MLQ-SS2B-CC: Dual-port serial CPU module, enhanced scan rate variant
• 2MLQ-SS4A-CC: Quad-port CPU module with extended memory, Q-series rack
• 2MLQ-SS4B-CC: Quad-port CPU, high-speed processing, redundancy-capable
• 2MLQ-RCPU-CC: Redundant CPU module for hot-standby configurations

Digital Input (DI) Modules

• 2MLQ-DI16A: 16-channel 24 VDC digital input, sink/source configurable
• 2MLQ-DI32A: 32-channel 24 VDC digital input, high-density rack mount
• 2MLQ-DI16B: 16-channel 120 VAC digital input module

Digital Output (DO) Modules

• 2MLQ-DO16A: 16-channel 24 VDC digital output, transistor sourcing
• 2MLQ-DO32A: 32-channel 24 VDC digital output, high-density
• 2MLQ-DO16R: 16-channel relay output module, 2A per channel

Analog Input (AI) Modules

• 2MLQ-AI8A: 8-channel analog input, 4–20 mA / 0–10 V, 12-bit resolution
• 2MLQ-AI16A: 16-channel analog input, differential, 16-bit resolution

Analog Output (AO) Modules

• 2MLQ-AO8A: 8-channel analog output, 4–20 mA, 12-bit resolution

Communication / Network Adapter Modules

• 2MLQ-PNIO-CC: PROFINET IO adapter module for MasterLogic Q-series rack
• 2MLQ-DNET-CC: DeviceNet master/slave communication module
• 2MLQ-MBUS-CC: Modbus RTU/TCP gateway module

Power Supply Modules

• 2MLQ-PS24A: 24 VDC rack power supply, 10A output, single-slot
• 2MLQ-PS24R: Redundant 24 VDC power supply module, hot-swap capable

Quality Control for the MasterLogic Range

MasterLogic CPU and communication modules incorporate proprietary backplane bus interfaces and internal ASIC-based communication controllers that require specialized test procedures beyond standard bench power-up verification. DriveKNMS applies the following protocol to all MasterLogic modules prior to dispatch: (1) Visual inspection of backplane connector pins, capacitor condition, and PCB trace integrity under 10× magnification. (2) Powered functional test using a dedicated MLQ test rack with known-good power supply and backplane, verifying CPU boot sequence, LED status codes, and self-diagnostic register outputs. (3) Communication port verification: each serial and network port is tested for correct framing, baud rate negotiation, and error-free data exchange over a minimum 30-minute cycle. (4) Memory integrity check: program memory, retentive data registers, and firmware CRC are validated against reference values. (5) Final burn-in: modules are operated under load for 4 hours at elevated ambient temperature (50°C) to screen for early-life component failures. All test results are documented and shipped with each unit.