Specifications

Page 14–2
FOCUS System Manual
14.2.1 PRI/PRS Capabilities
In addition to the basic point-to-point configura-
tion, the PRI module provides advanced network
features to further enhance the functionality of
your FOCUS network. These additional modes of
operation are:
• Addressed Point-to-Point (Fig. 14-1)
• Addressed Point-to-Point with high speed
switching to the redundant path (Fig. 14-2)
• Multi-Drop Linear Chain (Fig. 14-3)
• Multi-Drop Redundant Path (Fig. 14-4)
The addressed and redundant modes come
standard with all PRI/PRS modules shipped after
June, 2000. The Multi-drop features are optional
and specified by ordering PRI-M or PRS-M
modules.
14.2.1.1 Addressed Point-to-Point
This standard feature allows you to specify which
pair of PRI modules will communicate with each
other. You assign a local and remote address to
each PRI module in the network (as shown in Fig.
14-1). A PRI module will remain in block until it
receives the expected programmed address from
the other PRI module. On the channel map the
modules are labeled:
• PRI-A - addressed point-to-point
14.2.1.2 Addressed Point-to-Point with
redundant path
This is the same as Addressed Point-to-Point
except with the redundant path feature and is also
supplied as a standard feature. This option is a
safeguard if a network failure occurs within a ring
-configured FOCUS systems. Data is being trans-
mitted on both channel A (primary) and channel B
(redundant) simultaneously. Channel B (the
redundant path) is the reversed direction around
the protected ring. If channel A fails, the reception
of data is automatically switched to channel B,
providing it is error-free. This switching typically
When in redundant mode, if the PRI detects
either the primary or redundant path bad, the
status LED will blink alternately red/green
indicating a minor alarm. This blinking will
continue until the channel problem is fixed.
NOTE
In normal operation - if only one direction of a
PRI/PRS pair goes into block, the opposite
direction will remain in service. We offer
PRI/PRS version 50 for applications where it
is desired to block BOTH directions when
only one direction fails. This feature is
available for point-to-point applications only
with or without addressing.
NOTE
FOCUS
Substation #1
Substation #2
PRI module
Time slot 3
PRI module
Time slot 3
Mapped in FCS
Mapped in FCS
FOCUS
Mapped in FCS
Figure 14–1.
Addressed Point-to-Point PRI Modules