Hirschmann MM2 Series Modules: MM2-2FLM4

Technical Dossier

Product Details And Specifications

Hirschmann MM2 Series: Comprehensive Module Range and Technical Overview

The Hirschmann MM2 series represents a foundational product line in industrial Ethernet switching infrastructure, deployed extensively across heavy-industry sectors including petrochemical refineries, nuclear power generation facilities, offshore platforms, and large-scale chemical processing plants. Manufactured in Germany by Hirschmann Automation and Control GmbH (a Belden brand), the MM2 platform established a benchmark for modular, rail-mountable managed switches capable of operating in Class I Division 2 and ATEX-rated environments. Its ruggedized backplane architecture and deterministic forwarding behavior made it a preferred choice for SCADA backbone networks and DCS communication rings throughout the 1990s and 2000s. Installed base counts in the tens of thousands of units globally, meaning lifecycle support and spare parts availability remain critical operational concerns for plant engineers and maintenance teams well into the 2020s.

The Evolution of MM2 Architecture

The MM2 platform was introduced as a successor to Hirschmann's earlier Rail Hub and RS series, transitioning from shared-media coaxial and AUI-based topologies to structured, port-based 10/100 Mbps Ethernet switching. The core chassis design uses a passive backplane with modular media slots, allowing operators to mix copper RJ45, multimode fiber (MM), and singlemode fiber (SM) interfaces within a single unit. Early MM2 configurations shipped with fixed 10BASE-T uplinks; subsequent revisions introduced 100BASE-FX Fast Ethernet fiber ports and SNMP v1/v2c management capability. The MM2-2FLM4 specifically integrates four multimode fiber ports (100BASE-FX, ST connector, 2 km reach) alongside two fixed copper ports, making it a hybrid aggregation module suited for ring or star fiber backbone segments. As the platform matured, Hirschmann introduced RSTP (Rapid Spanning Tree) and HiPER-Ring proprietary redundancy protocols, which are backward-compatible with MM2 hardware via firmware upgrades. The MM2 line reached end-of-active-production status, though Hirschmann continued to supply spare modules through authorized channels. Compatibility with successor platforms (RS20, RS30, MACH100 series) requires media converters or uplink adapters; direct slot interchangeability does not exist between generations.

MM2 Full Catalog & Functionalities (SKU List)

The following SKUs represent verified, commonly deployed modules within the Hirschmann MM2 platform. Each entry reflects a distinct hardware configuration with a defined port type, media standard, and functional role.

MM2-2FLM4: 4-port 100BASE-FX multimode fiber media module, ST connector, 2 km reach, half/full duplex.
MM2-2FLS4: 4-port 100BASE-FX singlemode fiber media module, ST connector, 15 km reach.
MM2-2FLM2: 2-port 100BASE-FX multimode fiber module, ST connector, ring segment uplink.
MM2-2FLS2: 2-port 100BASE-FX singlemode fiber module, ST connector, long-haul backbone link.
MM2-2TP4: 4-port 10/100BASE-TX copper RJ45 module, auto-negotiation, standard DIN-rail fit.
MM2-2TP8: 8-port 10/100BASE-TX copper RJ45 expansion module, high-density access layer.
MM2-2TP2: 2-port 10BASE-T copper module, legacy segment bridging, half-duplex fixed.
MM2-2FLM4-EEC: Extended temperature variant of MM2-2FLM4, rated –40 °C to +70 °C, outdoor enclosure compatible.
MM2-2FLS4-EEC: Extended temperature singlemode fiber module, –40 °C to +70 °C, harsh environment rated.
MM2-2TP4-EEC: Extended temperature copper module, –40 °C to +70 °C, conformal coated PCB.
MM2-PS: Redundant 24 VDC power supply module for MM2 chassis, dual-input failover.
MM2-PS-AC: 100–240 VAC input power supply module, integrated into MM2 chassis slot.
MM2-MGT: SNMP management module, supports v1/v2c, RMON, port mirroring, VLAN configuration.
MM2-MGT-HiPER: Management module with HiPER-Ring redundancy protocol support, sub-300 ms failover.
MM2-CHASSIS-6: 6-slot passive backplane chassis, DIN-rail mount, accepts all MM2 media and management modules.
MM2-CHASSIS-10: 10-slot passive backplane chassis, extended configuration for high port-count deployments.
MM2-AUI: AUI transceiver adapter module, legacy coaxial network bridging to MM2 Ethernet backbone.

Sourcing Hard-to-Find & Obsolete MM2 Series Parts

The Hirschmann MM2 series has entered the obsolete/end-of-life phase of its product lifecycle. OEM new-stock availability through standard distribution channels is effectively exhausted. DriveKNMS maintains a dedicated inventory program for MM2 platform components, sourcing units from decommissioned plant assets, controlled surplus channels, and verified third-party refurbishers. All MM2 modules offered by DriveKNMS are subject to pre-shipment functional verification. For plant operators running MM2-based SCADA or DCS communication rings who cannot justify a full platform migration, DriveKNMS provides a lifecycle extension service: identifying compatible replacement modules, advising on firmware version alignment, and supplying tested spare units with documented test records. Requests for specific MM2 SKUs, chassis configurations, or bulk quantities for planned maintenance shutdowns should be submitted directly to the procurement team with full part numbers and required quantities.

Quality Control for the MM2 Range

MM2 modules present specific test challenges due to their passive backplane bus architecture and fiber optic media interfaces. DriveKNMS applies the following verification protocol to all MM2 units prior to dispatch: (1) Visual inspection of ST fiber connectors for end-face contamination, ferrule damage, and housing integrity. (2) Optical power measurement on each fiber port using a calibrated optical power meter, verified against Hirschmann's published TX/RX power specifications for 100BASE-FX. (3) Backplane connector pin inspection for oxidation, bent contacts, and mechanical seating integrity. (4) Powered functional test: module inserted into a reference MM2 chassis, link establishment verified on all active ports using a traffic generator, port LEDs and SNMP status polled via the MGT module. (5) For EEC-variant modules, thermal cycling verification is performed where test equipment permits. (6) Firmware version is read and documented; units with incompatible firmware for HiPER-Ring environments are flagged in the test record. All test data is retained and available to the customer upon request.