Siemens 6GK5991-4AB00-8AA0 SCALANCE X MM991-4 4x 100 Mbit/s BFOC Multimode 5 km Media Module

The Siemens 6GK5991-4AB00-8AA0 (MM991-4) is a SCALANCE X media module that adds four 100 Mbit/s BFOC/ST optical ports for multimode fiber. Each port covers a link of up to 5 km at 1310 nm, giving a switch four independent fiber segments from one media module slot. It operates from 0 to 60 degrees C, weighs 0.3 kg, and mounts in the module bay with a latched connector.

Technical Specifications

Certifications & Standards

• CE
• C-Tick
• KC
• BV
• EPD

Selection Notes

The MM991-4 carries four independent 100 Mbit/s ST/BFOC ports on one media module, so it fits SCALANCE X switches that need to fan out to four multimode fiber runs instead of one. At 5 km per port on 1310 nm multimode, it covers plant-floor distances between cabinets; for longer single-mode spans in the same 100 Mbit/s family, the LC single-mode media module or SFP is the better choice, not this multimode module. Because all four ports share one card, a fault on the module affects all four links at once, which is a factor to weigh against using four single-port SFPs when link independence matters.