OPERATION
Copyright 2007
5-26
S SC150e HARDWARE REFERENCE
The optional Fiber Optic Bypass Switch must be installed for the loopback to work.
However, in the absence of the Fiber Optic Bypass Switch, fiber-optic cables could be
run from the node’s transmitter output connectors to the receiver input connectors. This
configuration, with Insert Node enabled, would constitute a Fiber-optic Loopback mode
for stand-alone testing. The Disable Fiber-optic Loopback CSR2[6] must be set ON
when the node is in use as a part of the network. However, this configuration could not be
used in a network ring in the place of a Fiber Optic Bypass Switch because it would
cause a break in ring continuity.
The Fiber Optic Bypass Switch is used to provide fiber-optic ring continuity when a node
is powered down or in loopback mode. CSR2[6] controls the operation of the Fiber Optic
Bypass Switch by enabling or disabling Loopback mode. To disable the Fiber-optic
Loopback mode, set CSR2[6] ON. This state allows data to be transmitted and received
on the network ring for this node.
When the Fiber-optic Loopback mode is enabled (CSR2[6] OFF), the Fiber Optic Bypass
Switch prevents the node from receiving network data. Likewise, the node cannot
transmit any data into the network ring.
When power is lost to the Fiber Optic Bypass Switch, Fiber-optic Loopback mode is
enabled regardless of its prior state in order to maintain ring integrity. This is also the
default power-up state.
NODE INSERT MODE
In this mode the node becomes part of the network (Figure 5-9).
Table 5-11 Node Insert Mode
State Register
Setting
Receive Enable
CSR0[0]
ON
Transmit Enable
CSR0[1]
ON
Insert Node
CSR0[15]
ON
Enable Wire Loopback
CSR2[7]
OFF
Disable Fiber-optic Loopback
CSR2[6]
ON
Mechanical Switch Override
CSR8[11]
ON
NOTE
: Do not enable the Wire Loopback and Fiber-optic Loopback and/or Mechanical
Switch loopback modes simultaneously. A node in Wire Loopback mode and Insert
Node will create a break in the network ring that will disable all nodes.
Summary of Contents for SCRAMNet+ SC150e
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