Specifications

Page 5–2
FOCUS System Manual
neighbors’ addresses into FOCUS, the
entering of the loop definitions, selecting
channels to be skipped, and sending the ARM
and DISARM APM message.
5. No more than one (1) loop fault can be
tolerated at a time. A loop fault is defined as a
broken link between two nodes in one or both
directions or a failed FOCUS terminal. A
broken link condition can be a broken fiber or
wire or a bad transmitter or receiver at either
end of the link. A failed FOCUS terminal
condition is when a terminal is no longer
transmitting its Node ID or is transmitting a
wrong ID for whatever reason.
6. It is possible to disarm APM while the loop is
in APM (i.e., DOWN or FLIPPED). However,
the loop would return to the Primary Path
channel assignments.
5.1.1 How to Set up and Arm a Loop
(For complete instructions on specific FCS proce-
dures, please refer to the FCS online help.)
1. Power up each chassis in the loop.
2. Enter the time slot assignments on all chassis.
3. Ensure that the channel modules are commu-
nicating.
4. Get the terminal ID numbers (using the FCS
“Get T
erminal Identification Number”
function) from all the chassis and write them
on a piece of paper.
5. On each node:
a) Use the FCS “APM Define” function to
enter the adjacent terminal’s Terminal
Identification Number in appropriate list
boxes corresponding to the transceivers.
Select the loop definition which repre-
sents the transceivers involved to create
the closed loop.
b) Send the APM configuration information
to the FOCUS chassis and verify a
positive acknowledgment. (The FOCUS
chassis is queried before the dialog box is
displayed.)
c) Use the FCS “APM Status” function to
verify that the loop you are currently
setting up displays a status of “APM
READY.”
d) Lock the chassis.
6. After completing Step 5 on all nodes in the
loop, you may arm the loop as follows:
a) Unlock the chassis.
b) Use the “APM Arm” command to arm the
loop.
Note: The “Arm” command is only
available if the current status is “APM
READY.”
7. Verify that the loop is armed by performing at
least one of the following:
a) Receiving a positive acknowledgment
from the FOCUS chassis in response to
sending the “APM Arm” command. The
“Command Accepted” message box
indicates a positive acknowledgment.
b) View the target buffer using the “View All
Targets” command. If the loop was armed
successfully, the following target will be
logged:
∞ APM Loop 1 ARMed Successfully
c) View the APM Status using the “APM
Status” command. The status should be
either ARMED or FLIPPED.
The FLIPPED status indicates the loop is
ARMED and currently in Alternate Path
Mode. (A break has been detected by
another node in the loop. )
d) Look at the status LEDs on the front panel
of the FOCUS Chassis, the APM status
LED should be on (green LED, right side,
third row from top).
8. If the previous step indicates that the loop is
NOT armed, you can do the following to find
out why the loop did not arm.
View the target buffer. The following system
target should be logged:
APM Loop 1 ARM Failed Address:xxxx,
Reason: yyyy