PRODUCT OVERVIEW
Copyright 2007
3-5
S SC150e HARDWARE REFERENCE
3.6 Options
3.6.1 Fiber Optic Bypass Switch
A Fiber Optic Bypass Switch is a moving fiber switch that can redirect the fiber-optic
path to change source and destination in a ring configuration. By placing a bypass switch
between the node and the ring, the transmitter and receiver paths are controlled by the
switch.
BYPASS MODE
When a node is powered down, the bypass switch automatically routes the network data
around the node. This keeps the fiber-optic ring operational. If there were no bypass
switches in place when the node was powered down, there would be no means to receive
or transmit incoming network data. Hence, the ring would be broken and no network
traffic could occur. The bypass switch allows the data to continue on as if there were no
node there at all.
When the switch is in the bypass state, the node is enabled to transmit data out and then
right back into itself through the switch without going out onto the ring. Likewise, ring
traffic “bypasses” the node through the switch. The LED on the switch will not be
illuminated during this state.
INSERTED MODE
When a node is powered up, the switch is automatically in the bypass state by default.
With power at the node, the bypass switch is under software control. By setting a bit in
one of the S SC150e node’s control registers, the switch can be placed in the
“inserted” mode. The control signals are passed by an electrical connection between the
node and the bypass switch using the 8-Pin Mini-DIN connector provided with the
bypass switch. Refer to section 4.7 for instructions to interface the S SC150e
card with the bypass switch.
NOTE
: Details for setting Status/Control Registers are contained in Appendix B.
When the fiber switch is in the inserted state, the node is enabled to transmit data onto the
ring and receive data from the ring while passing through the switch. The LED indicator
on the switch will be illuminated during this state. Nodes 1, 3, 4, and 6 in Figure 3-4 are
in the inserted state.
FUNCTIONALITY
The S SC150e network is based upon a fiber-optic-ring topology. While a
fiber-optic configuration has many advantages a ring configuration depends on
connectivity. If any of the nodes in a fiber-optic ring loses the ability to retransmit an
incoming message, then the ring is “broken.”
Summary of Contents for SCRAMNet+ SC150e
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