HIRSCHMANN MM20-M4T1T1T1SAHH Hybrid Fast Ethernet Media Module
HIRSCHMANN MM20-M4T1T1T1SAHH (order code designation: MM20-M4T1T1T1SAHH…) is a hot-swappable hybrid Fast Ethernet Media Module engineered for Hirschmann’s modular MICE (Modular Industrial Communication Equipment) Switch family (MS20 and MS30 series).
Unlike dual-fiber models, this unit features a 1 x Multimode ST fiber optic port alongside 3 x RJ45 copper ports. This asymmetrical configuration makes it ideal for drop-node network architectures where a single optical uplink or downstream leg is needed alongside multiple copper field device drops.
Unique Product Description
Hirschmann MM20-M4T1T1T1SAHH is a 4-port hybrid Fast Ethernet media module offering 1 x ST multimode optical fiber port and 3 x RJ45 copper ports for MS20/30 modular switch backplanes. Engineered for standard industrial automation setups, it enables single-fiber spur connections or optical uplinks while providing three direct copper interfaces for local PLCs, HMIs, or sensors—all within a single hot-swappable slot without disturbing active network operations.
Product Advantages and Features
Asymmetrical As-Needed Port Mix: Provides 1 x 100Base-FX Multimode ST port ($1300\text{ nm}$) and 3 x 10/100Base-TX RJ45 copper ports, saving slot space when only one fiber connection is required.
Rugged ST Bayonet Locking: The ST fiber connector features a twist-lock bayonet mechanism to prevent cable displacement caused by cabinet vibration.
Hot-Swappable Backplane Integration: Easily plugs into or unplugs from live MS20 or MS30 basic switch units, eliminating maintenance downtime for surrounding media modules.
Auto-MDI/MDI-X & Auto-Speed Sensing: All three copper ports automatically detect line speeds (10/100 Mbps) and cable pinouts, removing the need for specialized crossover cables.
Energy-Efficient Design: Operates directly via the host switch backplane with low overall power consumption ($\approx$ 4W to 6W).
On-Board LED Diagnostics: Front-panel LEDs provide immediate visual feedback for power supply, individual port link status, speed, and active data transmission.
Application Cases
Terminal Control Cabinets: Connects a localized cluster of up to 3 copper devices (e.g., a PLC, HMI screen, and drive controller) back to an optical backbone ring via its single ST fiber uplink.
Conveyor & Material Handling Spurs: Serves as a branch node along long industrial conveyor lines where a single fiber drop branches into local field device connections.
Substation Diagnostics & Monitoring: Provides noise-immune fiber isolation for incoming data while connecting local monitoring equipment via shielded twisted-pair copper.
Machine Tool Manufacturing: Integrates localized CNC control units and peripheral sensor nodes into plant-wide Ethernet infrastructure.
Other Models in the Same Series
The Hirschmann MICE MM20/MM30 Series allows precise customization of copper, fiber, and hybrid options across various connector types and temperature ratings:
| Model Part Number | Port Mix / Configuration | Connectors / Environmental Rating |
| MM20-M4T1T1T1SAHH | 1 x Multimode Fiber + 3 x RJ45 | ST Connector / Standard Temp ($0^\circ\text{C}$ to $+60^\circ\text{C}$) |
| MM20-M4M4T1T1SAHH | 2 x Multimode Fiber + 2 x RJ45 | ST Connectors / Standard Temp ($0^\circ\text{C}$ to $+60^\circ\text{C}$) |
| MM20-M2M2M2M2SAHH | 4 x Multimode Fiber | SC Connectors / Standard Temp ($0^\circ\text{C}$ to $+60^\circ\text{C}$) |
| MM20-T1T1T1T1SAHH | 4 x 10/100Base-TX | All-Copper RJ45 / Standard Temp ($0^\circ\text{C}$ to $+60^\circ\text{C}$) |
| MM20-T1T1T1T1EBH | 4 x 10/100Base-TX | All-Copper / Extended Temp ($-40^\circ\text{C}$ to $+70^\circ\text{C}$) + Conformal Coated |
| MM20-Z6Z6SAHH | 4 x Fast Ethernet SFP Slots | SFP Slots / Standard Temp ($0^\circ\text{C}$ to $+60^\circ\text{C}$) |
Installation and Maintenance
Installation
Electrostatic Protection: Put on an ESD grounding wrist strap before handling the module to prevent static damage.
Backplane Insertion:
Locate an open media slot on the host MS20 or MS30 switch frame.
Align the module with the internal guide rails and push firmly until the backplane connector locks in place.
Mechanical Fastening: Hand-tighten the captive thumbscrews on the top and bottom of the front plate to lock the module chassis and ensure proper grounding.
Cabling Connections:
Fiber Port: Push and twist the ST bayonet connector onto the optical port (verify Tx/Rx routing with the remote end).
Copper Ports: Insert shielded Cat5e/Cat6 cables into the RJ45 jacks until the retaining clip snaps in place.
Maintenance
Hot-Swap Replacement: To service or swap the module during live operation, disconnect connected copper and fiber lines, loosen the captive screws, and pull the unit out. Insert the replacement unit without shutting down power to the parent switch.
Cleaning & Port Caps: Keep rubber dust covers installed on unused RJ45 jacks or the ST optical ferrule to prevent dust contamination. Clean optical fiber tips with an optical-grade cleaning pen if signal degradation occurs.