The FCM10Ef Fieldbus Communications Module is a fiber optic communications interface which allows the DIN rail mounted Fieldbus Modules (FBMs) to communicate with the I/A Series control station over extended distances using fiber optic cabling. The FCM10Ef modules provide expanded networking, easy customization, and greater overall cabling distances in a fiber optic network (see Figure 1). This configuration is ideally suited for sites in which groups of FBMs are to be spread apart over greater distances.
FCM10Ef modules are used with multiport fiber optic converters (hubs), which connect to the I/A Series control station via the high-speed, optionally redundant 10 Mbps Ethernet trunk Fieldbus.
Up to six groupings of baseplate-mounted FCM10Ef modules and FBMs can be linked to each optionally redundant multiport fiber optic converter (hub), for a maximum of 120 FBMs per I/A Series control station (depending on selected scan periods). To support redundancy, a pair of FCM10Ef modules must be used for each FBM grouping. In non-redundant configurations, only a single FCM10Ef is required for each grouping.

Signal transmission distances up to 2 km (1.24 mi) are possible between the FCM10Ef modules and the multi-port fiber optic converters (hubs), providing for wide distribution of the FBM equipment groupings.
Extended transmission distances, using fiber optic cabling, are also possible within the groupings, and between the multiport fiber optic converter (hub) and the I/A Series control station. (Refer to PSS 21H-2W1 B3, for details.)

Unaffected by electrical noise (EMI, RFI, and lightning), fiber optic cabling provides a versatile, highly reliable means of extending signal communications. It can be used in areas containing rotating machinery, arc welders, and so forth, and can be installed in cable trays containing high voltage power lines, or in outdoor areas exposed to lightning hazards. Its electrical isolation characteristics provide protection from voltage differentials and ground loops.
Fiber optic cabling used in this configuration is purchased by the customer. The recommended fiber optic cable is a multimode, graded-index glass fiber with a 62.5 micron core and 125 micron cladding with 0.275 NA (numerical aperture).
Maximum allowable signal loss is 1 dB per km at a wavelength of 1300 nm, and 3.6 dB per km at a wavelength of 850 nm. Cables with different characteristics may not be used. Four fiber optic cables are required for redundancy, two for transmit and two for receive connections. For this reason, it is recommended that the customer purchase duplex cabling, which consists of two fibers intertwined in a single cable. The cables must be terminated with ST-type connectors and cable length may not exceed that specified for the module.