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The Honeywell 2MLR-DBDT is a Redundant Expansion Driver for the MasterLogic-200R PLC system. It provides the communication interface between the redundant CPU system and remote I/O expansion bases through a TP (Twisted Pair) network connection.
In a distributed automation installation, the main CPU rack may be located in a central control cabinet, while additional I/O modules are installed in separate expansion bases closer to field equipment. The 2MLR-DBDT handles the communication link required to exchange data between these assemblies. Its redundant configuration supports dual I/O communication paths, helping maintain connectivity if one communication path encounters a fault.
For example, in a process plant with multiple distributed control cabinets, the main MasterLogic-200R controller may need to communicate with I/O modules installed in remote sections of the facility. The 2MLR-DBDT provides the TP communication interface for the redundant expansion arrangement, allowing the controller to exchange input and output information with the expansion system.
The module is intended for installation in the designated expansion-driver position of a compatible MasterLogic-200R expansion base. It works alongside the redundant expansion base, I/O modules, and associated communication cabling. It is not a standalone Ethernet switch or a general-purpose network adapter.
The distinction between the 2MLR-DBDT and other MasterLogic expansion drivers is mainly related to communication media and redundancy configuration. The 2MLR-DBDT uses twisted-pair communication in a redundant expansion arrangement, while the 2MLR-DBDF uses fiber-optic communication and the 2MLR-DBDH supports a hybrid TP/FO configuration.
| Parameter | Specification |
|---|---|
| Manufacturer | Honeywell |
| Model | 2MLR-DBDT |
| Product Series | MasterLogic-200 |
| System Type | MasterLogic-200R |
| Product Type | Redundant Expansion Driver |
| Module Category | Redundant Expansion Driver Module |
| Communication Interface | TP (Twisted Pair) |
| Communication Media | CAT5 Ethernet Cable |
| Network Configuration | Dual I/O Link Redundancy |
| Installation Position | Expansion Driver Connector on Redundant Expansion Base |
| Compatible Expansion Base | 2MLR-E12H |
| Current Consumption | 550 mA |
| Dimensions | 150 × 25 × 100 mm |
| Weight | 0.1 kg |
The 2MLR-DBDT operates as the communication interface between the MasterLogic-200R CPU system and its redundant I/O expansion network.
Its operation is based on the exchange of digital data between the main controller and distributed expansion bases. The module uses a TP/CAT5 communication connection and participates in the system’s dual-link redundancy arrangement.
The basic communication path is:
MasterLogic-200R CPU → Redundant Expansion Driver → TP/CAT5 Network → Remote Expansion Base → I/O Modules
During normal operation, the CPU exchanges information with the remote I/O system through the configured communication links. Input data collected by the expansion modules is transmitted toward the controller, while output commands are delivered to the corresponding output modules.
The redundant architecture provides an additional communication path. If one I/O communication link becomes unavailable, the system can use the remaining available path according to its configured redundancy logic.
This arrangement is particularly useful in process installations where a communication interruption between the controller and remote I/O racks could affect equipment operation.
The 2MLR-DBDT does not independently execute PLC programs or perform field signal conversion. Its function is to maintain the communication interface required by the redundant expansion architecture. Actual control logic remains with the CPU, while individual I/O modules handle the connected field signals.
The 2MLR-DBDT occupies the expansion-driver position within the MasterLogic-200R redundant I/O architecture.
It works with the 2MLR-E12H redundant expansion base and the corresponding CPU and I/O hardware. The driver establishes the communication interface needed to connect the expansion base to the controller’s redundant I/O network.
MasterLogic-200R CPU → Main Base → Redundant I/O Communication Network → 2MLR-DBDT → 2MLR-E12H Expansion Base → I/O Modules → Field Devices
| System Component | Function |
|---|---|
| 2MLR-CPUH/T or 2MLR-CPUH/F | Executes PLC control logic and manages the redundant controller architecture |
| 2MLR-M02P | Main CPU base for a two-module installation |
| 2MLR-M06P | Main CPU base for a six-module installation |
| 2MLR-DBDT | Provides the TP communication interface for redundant I/O expansion |
| 2MLR-E12H | Redundant expansion base supporting dual I/O link redundancy |
| 2MLR-DBDF | Provides the fiber-optic redundant expansion communication option |
| 2MLR-DBDH | Provides the hybrid TP/FO redundant expansion communication option |
| MasterLogic I/O Modules | Acquire field inputs and control connected output devices |
| Field Instruments | Supply process measurements and equipment status signals |
| Industrial Actuators | Execute output commands from the control system |
The 2MLR-DBDT should be selected according to the communication medium and redundancy arrangement specified for the existing MasterLogic-200R installation.
The 2MLR-DBDT is suitable for MasterLogic-200R installations where remote I/O communication uses a redundant twisted-pair network arrangement.
| Industrial Application | Typical Use |
|---|---|
| Oil and Gas Processing | Connecting distributed I/O racks in process control installations |
| Petrochemical Plants | Maintaining redundant communication between CPU and expansion bases |
| Chemical Processing | Supporting distributed monitoring and control signals |
| Power Generation | Connecting remote I/O assemblies within plant control systems |
| Water Treatment Facilities | Supporting communication with distributed process I/O |
| Industrial Manufacturing | Expanding PLC I/O capacity across production areas |
| Compressor Stations | Connecting remote equipment monitoring and control points |
| Refinery Automation | Supporting redundant I/O communication in process units |
| Utility Control Systems | Integrating distributed field signals into a central PLC |
| Continuous Process Plants | Maintaining communication availability across distributed I/O installations |
During troubleshooting, inspect both communication paths rather than checking only the primary connection. A fault in one path may affect redundancy even when the remaining path continues to exchange data.
| Component | Function |
|---|---|
| Honeywell 2MLR-CPUH/T | Redundant CPU with TP communication configuration |
| Honeywell 2MLR-CPUH/F | Redundant CPU with fiber-optic configuration |
| Honeywell 2MLR-E12H | Redundant expansion base with 12 slots |
| Honeywell 2MLR-DBST | Non-redundant expansion driver, TP |
| Honeywell 2MLR-DBSF | Non-redundant expansion driver, FO |
| Honeywell 2MLR-DBSH | Non-redundant expansion driver, TP/FO |
| Honeywell 2MLR-DBDF | Redundant expansion driver, FO |
| Honeywell 2MLR-DBDH | Redundant expansion driver, TP/FO |
| Honeywell 2MLC-F201 | Multimode fiber-optic synchronization cable with LC connectors |
| Honeywell MasterLogic-200 I/O Modules | Handle distributed digital and analog field signals |
| Model / Product Family | Product Type | Typical Application |
|---|---|---|
| Honeywell 2MLR-DBDF | Redundant Expansion Driver, FO | Fiber-optic redundant I/O communication |
| Honeywell 2MLR-DBDH | Redundant Expansion Driver, TP/FO | Hybrid twisted-pair and fiber-optic communication |
| Honeywell 2MLR-DBST | Expansion Driver, TP | Non-redundant TP expansion communication |
| Honeywell 2MLR-DBSF | Expansion Driver, FO | Non-redundant fiber-optic expansion communication |
| Honeywell 2MLR-E12H | Redundant Expansion Base, 12 Slot | Distributed I/O expansion |
| Honeywell 2MLR-CPUH/T | Redundant CPU, TP Configuration | MasterLogic-200R redundant controller architecture |
Both are redundant expansion drivers for the MasterLogic-200R system, but they use different communication media. The 2MLR-DBDT uses TP/CAT5 twisted-pair communication, while the 2MLR-DBDF uses fiber-optic communication. The choice depends on the existing network infrastructure and installation requirements.
The 2MLR-DBDT is associated with the 2MLR-E12H redundant expansion base. This base supports the dual I/O link redundancy architecture and provides the designated position for the redundant expansion driver.
Not as a direct like-for-like replacement in every installation. The 2MLR-DBDT belongs to the redundant expansion-driver family, whereas the 2MLR-DBST is a standard TP expansion driver. The base configuration and required I/O communication architecture must be checked before substitution.
Start by checking the TP/CAT5 cable connections and the status of both redundant communication paths. Then inspect the expansion-driver installation, expansion-base connections, and controller configuration. If only one communication path has failed, the system’s redundancy arrangement may allow the remaining path to continue operating, depending on the configured architecture.