ProSoft MVI71-AFC: MVI71 Series Modules,

Technical Dossier

Product Details And Specifications

ProSoft Technology MVI71 Series: Comprehensive Module Range and Technical Overview

The ProSoft Technology MVI71 series is a line of communication and protocol gateway modules engineered for the Rockwell Automation Allen-Bradley PLC-5 backplane. Deployed across heavy industrial sectors including petrochemical refineries, offshore oil & gas platforms, nuclear power generation facilities, and large-scale water treatment infrastructure, the MVI71 platform has accumulated a substantial global installed base since its introduction in the late 1990s. These modules occupy a single slot in the PLC-5 rack and communicate with the processor via the backplane data transfer mechanism, enabling legacy PLC-5 systems to interface with modern fieldbus networks, flow computers, SCADA protocols, and serial device networks without processor replacement. The MVI71-AFC specifically implements the American Flow Computer (AFC) protocol, providing gas and liquid flow measurement and computation functions directly within the PLC-5 environment — a configuration common in custody transfer and fiscal metering applications at pipeline terminals and LNG facilities.

The Evolution of MVI71 Architecture

The MVI71 platform was developed as a direct response to the protocol isolation problem inherent in the Allen-Bradley PLC-5 architecture. Early PLC-5 systems (PLC-5/10, PLC-5/20, PLC-5/40, PLC-5/80) provided DH+ and Remote I/O as native communication channels, with no native support for Modbus RTU, PROFIBUS DP, DNP3, or serial ASCII protocols that were becoming standard in field instrumentation by the mid-1990s.

ProSoft's MVI71 modules resolved this by acting as an intelligent co-processor: each module contains an onboard microprocessor, protocol firmware, and a shared memory buffer (typically 4,000–8,000 16-bit registers) that the PLC-5 processor reads and writes via block transfer instructions (BTR/BTW). This architecture remained consistent across the entire MVI71 generation, ensuring a high degree of firmware and configuration tool compatibility across models.

By the mid-2000s, Rockwell Automation had begun transitioning customers toward the ControlLogix (1756) and CompactLogix (1769) platforms. ProSoft responded with the MVI56 and MVI69 series as functional equivalents for those platforms. As of 2026, the MVI71 series is classified as a mature/end-of-life product line. Rockwell Automation has discontinued the PLC-5 processor family, and replacement processors are no longer manufactured. This places the entire MVI71 ecosystem in a long-term maintenance and lifecycle extension phase, where sourcing of spare and replacement modules from authorized secondary-market distributors is the primary support pathway for facilities that cannot justify a full control system migration.

MVI71 Full Catalog & Functionalities (SKU List)

The following SKUs represent verified models within the ProSoft Technology MVI71 series, organized by functional category. Each module occupies one PLC-5 rack slot and interfaces via backplane block transfer.

Flow Computer & Metering Protocols

• MVI71-AFC: American Flow Computer protocol gateway for gas/liquid custody transfer metering in PLC-5 racks.
• MVI71-DFCM: Daniel Flow Computer Modbus interface; connects Daniel Senior Sonic and turbine meters to PLC-5.
• MVI71-MNET: Modbus TCP/IP client/server module; bridges Ethernet Modbus devices to PLC-5 backplane registers.

Serial & Modbus Protocols

• MVI71-MCM: Modbus RTU/ASCII master and slave; the most widely deployed MVI71 variant across process industries.
• MVI71-MCDMR: Modbus RTU master with redundancy support; dual-port serial for fault-tolerant Modbus networks.
• MVI71-GSC: Generic Serial Communication module; configurable ASCII/RTU for non-standard serial field devices.
• MVI71-GSCS: Generic Serial Communication with enhanced buffer; supports larger data payloads for complex serial instruments.

PROFIBUS Protocols

• MVI71-PDPMV1: PROFIBUS DP-V1 master module; connects PLC-5 as DP master to PROFIBUS field device networks.
• MVI71-PDPS: PROFIBUS DP slave module; allows PLC-5 to appear as a DP slave on an existing PROFIBUS master network.

DNP3 & Utility Protocols

• MVI71-DNP: DNP3 master/slave module; standard in electric utility SCADA and water/wastewater telemetry applications.
• MVI71-DNPSNET: DNP3 over Ethernet (serial tunneling); extends DNP3 connectivity across TCP/IP infrastructure.

IEC & Telecontrol Protocols

• MVI71-101S: IEC 60870-5-101 slave module; used in European utility SCADA and substation automation systems.
• MVI71-104S: IEC 60870-5-104 slave module; IEC 101 protocol transported over TCP/IP networks.

DeviceNet & ControlNet

• MVI71-ADN: DeviceNet scanner/adapter module; connects PLC-5 to DeviceNet device-level networks.
• MVI71-ACN: ControlNet adapter module; provides ControlNet connectivity for PLC-5 racks lacking native ControlNet capability.

Specialty & Legacy Protocols

• MVI71-HART: HART master module; reads HART secondary variables from 4–20 mA field instruments via RS-485 multidrop.
• MVI71-PBASIC: ProSoft BASIC module; programmable co-processor for custom protocol or data manipulation logic.

Sourcing Hard-to-Find & Obsolete MVI71 Parts

With Rockwell Automation having formally discontinued the PLC-5 processor line, the MVI71 series has entered a permanent secondary-market sourcing phase. New production units are no longer available from ProSoft Technology's standard distribution channels for most models. Facilities operating PLC-5-based control systems — particularly in industries where control system migration carries high regulatory, safety, or capital cost barriers (nuclear, refining, pipeline) — require access to tested, verified replacement modules to maintain system uptime.

DriveKNMS maintains a dedicated inventory of MVI71 series modules sourced through controlled secondary-market channels. All units are subject to pre-sale functional verification. For the MVI71-AFC specifically, DriveKNMS stocks units configured for standard AFC protocol operation and can supply the ProSoft Configuration Builder (PCB) configuration files and wiring documentation upon request. For facilities requiring multiple MVI71 variants as part of a planned maintenance stock or emergency replacement program, DriveKNMS can provide consolidated sourcing across the full MVI71 catalog from a single purchase order.

Quality Control for the MVI71 Range

MVI71 modules present specific verification challenges due to their backplane-dependent communication architecture. Standard power-on tests are insufficient to confirm functional integrity; full verification requires simulation of the PLC-5 block transfer environment.

DriveKNMS applies the following verification procedures to all MVI71 units prior to dispatch:

• Backplane Communication Test: Each module is installed in a live PLC-5 test rack and block transfer read/write cycles are executed to confirm data exchange integrity across the full register map.
• Protocol Port Verification: Serial ports (RS-232/RS-485) are tested with protocol-specific traffic. For MVI71-AFC units, AFC poll/response sequences are verified against a reference flow computer simulator.
• Firmware Version Audit: Onboard firmware revision is recorded and cross-referenced against ProSoft's published compatibility matrix for the target PLC-5 processor firmware revision.
• Visual and Component Inspection: PCB inspection for capacitor condition, connector pin integrity, and evidence of thermal stress or prior field repair.
• Configuration Backup: Where a prior configuration is present in flash memory, it is extracted and archived before any test cycle modification.

For MVI71-AFC availability, pricing, and technical documentation requests:

• Email: [email protected]
• WhatsApp: +86 18359293191
• Web: driveknms.com