The FOI-4451 and FOI-4541 both provide complete electrical isolation for RS- 422 communications. The units are transparent to all handshaking protocols and can accept data and clock signals up to a maximum rate of 6.144 Mbps. A regeneration switch on the FOI-4451 allows users to toggle between synchronous applications that require Send Timing (ST) and asynchronous or synchronous applications that require Terminal Timing (TT). They support tail circuit and null modem functions for DCE to DCE or DTE to DTE communications. This requires two of the same FOI units. An alternate interface (V.35 or RS-232) may be installed at the opposite end, allowing the user to create a link between two electrically incompatible interfaces without requiring a separate interface converter.
The units can be used in areas of high electrical noise or in and out of RF shielded enclosures. The fiber optic cable is not susceptible to interference caused by impulse noise, crosstalk, or EMI. Privacy of communications is also enhanced because the fiber optic cable does not radiate any emissions. FiberPlex recommends “T” units for high security applications because they have been TEMPEST tested and approved. In addition, fiber optic cable offers much longer transmission distances than traditional RS-422 cabling. Multimode optics on the units can extend the distance to 2km, while singlemode optics can further extend the distance to 20km. A typical link consists of an FOI-4451 at the Data Communication Equipment (DCE) and an FOI-4541 at the Data Terminal Equipment (DTE) with a duplex fiber optic cable between them.
Flexible Mounting and Powering Options
The FOI-4451 and FOI-4541 are part of the FOI line of products designed for ruggedized mil applications. They are housed in the familiar FOI shielded can enclosure. For standalone applications they can be powered by adding a PSQ‐4909 AC supply or a PSQ‐4920 DC power supply (not included). Optionally, up to 8 FOI units can be mounted on CMA chassis adapters and installed in an RMC‐3101 or RMC‐2101 rack mount chassis. The units are powered redundantly by a common back plane connection.