891 Ring for RS232 devices

CYGNUS 891 Ring for RS232 devices

red_arrow  Allows a number of Async user devices to communicate with each other over an optical fiber ring.
red_arrow  Available in two models. 891R offers 1 or 2 user ports. 891C offers 4 or 8 user ports.
red_arrow  Supports point to point and multipoint networking between user devices.
red_arrow Each unit has 2-way fiber connectivity to other nodes and acts as a node in interconnected ring or linear topology.
red_arrow  A CYGNUS 891 based fiber ring can have up to 32 nodes in case of multipoint half-duplex communication, and 9 nodes in case of point to point full-duplex communication between user devices.
red_arrow  Offers ring protection, i.e., handles failure of one segment of the ring through redundancy in data transmission.
red_arrow Carves out multiple (up to 8) user channels (called Virtual circuits, VCs) on the fiber, to allow as many independent high and medium speed user channels to operate simultaneously.
red_arrow  Each VC can support either:
         • Point-to-point full-duplex connectivity between any two user ports on 891 units in the ring, OR
         • Multipoint half-duplex connectivity network between a number of user ports which share the same virtual circuit. Each such multidrop network can have its own master and slave devices distributed over the fiber ring.
red_arrow  For use in point to point applications 891R may be ordered with RS232, RS422 or 20 mA current Loop user interface, while 891C may be ordered with RS232 or RS422 interface. For multipoint half duplex applications both 891R and 891C may be ordered with 2-wire RS485 interface.
red_arrow  The 891R model can optionally be supplied with a ethernet-to-serial terminal server module. Using this module, a remote host can send serial data encapsulated in ethernet packets over TCP/IP or UDP/IP protocol and thereby participatein point to point or multipoint connections over the fiber ring.
red_arrow  A pair of 891R or 891C units interconnected with fiber can act as a pair of Multiplexers and be used for transporting data from multiple ports (RS232, RS422 or RS485) over the fiber. If the two units have different user interfaces, interface conversion is also simultaneously accomplished. A multiplexer type setup can also be used for interconnecting 2-wire multipoint RS485 network segments.
red_arrow  A unit designated as Ring Master continuously polls other units to monitor the health of the Ring. The health report can be seen using a RS232 terminal console connected to the Master 891R unit.
red_arrow  Option of 1500 VAC isolation protection is available for RS232, RS422, RS485 and current loop interfaces. This helps in protecting the unit from damage that could be caused by faults in the user equipment.