ProSoft MVI56-MBP Communication Module – Obsolete Modbus Plus Spare Part for ControlLogix

Technical Dossier

Product Details And Specifications

ProSoft MVI56-MBP Communication Module – Obsolete Modbus Plus Spare Part for ControlLogix

RFQ support for obsolete parts: Send the model number, required quantity and destination so DriveKNMS can confirm sourcing options before quotation.

Technical Specifications

Solving the Discontinued Hardware Crisis

The MVI56-MBP was purpose-built to bridge Allen-Bradley ControlLogix systems with Modbus Plus networks — a protocol developed by Modicon (now Schneider Electric) that remains deeply embedded in legacy automation infrastructure across petrochemical plants, water treatment facilities, and heavy manufacturing lines installed between the late 1990s and early 2010s.

Modbus Plus is not Modbus RTU or Modbus TCP. It is a proprietary token-passing network that operates at 1 Mbps over a dedicated coaxial or twisted-pair bus. Devices on a Modbus Plus network cannot be accessed by standard Modbus gateways without a protocol-specific interface module. The MVI56-MBP is one of the few third-party modules that provided this bridge natively within the ControlLogix chassis.

With ProSoft Technology having discontinued the MVI56-MBP, there is no direct new-production replacement available from the original manufacturer. Facilities that still operate Modbus Plus field networks — and have ControlLogix as their primary PLC platform — face a binary choice: source verified spare MVI56-MBP units to maintain the existing architecture, or fund a full network migration to a supported protocol such as EtherNet/IP or Modbus TCP. The latter option is rarely cost-neutral. For a mid-size refinery or chemical plant, a Modbus Plus network may connect 30 to 80 field nodes. Migrating each node requires hardware replacement, loop testing, and process validation — a multi-year capital project.

Condition & Reliability Assurance

All MVI56-MBP units supplied by DriveKNMS pass a structured 5-stage quality verification process before dispatch:

• Stage 1 – Visual and Mechanical Inspection: Full examination of the module housing, backplane connector pins, and front-panel port for physical damage, corrosion, or evidence of prior field failure.
• Stage 2 – Electrolytic Capacitor Assessment: Capacitors on legacy communication modules are a primary failure point after extended storage or field use. Each unit is assessed for capacitor bulge, leakage, or ESR deviation from specification.
• Stage 3 – Firmware Version Verification: The installed firmware revision is documented and cross-referenced against known compatibility requirements for the target ControlLogix firmware environment.
• Stage 4 – Pin and Connector Integrity Check: Backplane connector pins are inspected under magnification for oxidation, bending, or contamination that could cause intermittent communication faults after installation.
• Stage 5 – Functional Communication Test: Where test bench infrastructure permits, the module is powered and its Modbus Plus port activity is verified prior to packaging.

Key Features for System Maintenance

Q: Can the MVI56-MBP be used with ControlLogix L8x series controllers?
A: Compatibility depends on the ControlLogix firmware revision and the ProSoft add-on instruction version in use. DriveKNMS can advise on known compatibility combinations based on your specific system configuration — provide your controller catalog number and firmware revision when enquiring.