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Product Description

The Model 2277 is a unique asynchronous fiber optic modem whose optical interface can operate in either point to point or ring (daisy chain) configurations and whose electrical interface can also operate in point to point or multi-drop configurations depending on the user selected interface.

For a point to point configuration, two Model 2277's are connected back to back to form a high speed, full du-plex, optical link. In an optical ring configuration, three or more Model 2277's, in all 4-wire modes are daisy chained in a ring. The ring will consist of a master Model 2277 and two or more slave 2277's. Mas-ter/slave modes are switch selectable. The slaves pass the received optical data along with the transmit data from their own electrical interface to their optical trans-mitters. The master does not pass the received optical data. A ring of up to 10 units at a data rate of 1 MBPS can be formed. To extend the optical distance a pair of Model 2277's can be inserted in the optical path to act as a line extender.

The Model 2277 electrical interface is switch selectable between RS-232, RS-422 and RS-485. Switch selec-tion enables data to flow from the electrical interface to the optical transmitter or to be controlled by the Request To Send, RTS, line. Full duplex four wire, or half duplex, four or two wire may be selected when the RS- 422, RS-485 interface is selected. The RS-422, RS-485 interfaces of the Model 2277 may operate in a multi-dropped or point to point environment.

In the half duplex mode the Model 2277 controls the transmit data line on the electrical interface.

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