1558A APS
3-4
Operation
3.2.9
Line Availability Timer
The line availability timer is used to quantify when a path is
eligible to accept service.Line availability is determined by
the APS by observing a defined window of time in which no
active error events have occurred. The APS line availability
timer can be set to any value from 0-900 seconds. This
value represents the minimum amount of time, free of active
error events, that must expire before this path is declared as
ready to accept service. The factory default setting for the
line availability timer is 60 seconds.
The line availability timer requires storage for the timer set-
ting and the active timer count. If the timer setting is 0, the
timer circuitry is disabled and the path is always available
for service, assuming that there are no active alarm condi-
tions present. If the timer setting is set to a value ranging
from 1 to 900 seconds and a service transfer takes place, the
standby unit initializes the active timer count to the timer
setting. When the timer expires, this standby path becomes
available for a service transfer. This timed period must be
free of errors for all active events. If an error occurs, the
active timer count is reset.
When operated in the optional revertive mode, the path
availability timer serves to force restoration of service back
to the default access, Path A. That is, when service is
switched from Path A, it will remain on the standby path
(Path B) only until Path A’s availability timer expires. The
factory default is Revert set to OFF.
3.2.10 Status and Performance Information
The current status and performance parameters are stored in
the internal registers of the 1558A. Access to this informa-
tion is via the 1559 APSM site manager (optional) or the
LAPS (local access protection switch) PC software. The
LAPS software is shipped with each 1558A unit.
The following information can be viewed by the user using
either the 1559 APS Site Manager or the provided APS
Local Access DOS Software.
• This path is currently carrying the service.
• This path is currently in a failed state.
• This path is currently in an inhibit state.
• The LB of this path is currently activated.
• The other path is currently in a failed state.
• The other path is currently in an inhibit state.
• The LB of the other path is activated.
• The manual locked control state.
• Current status
• Current interval Occurrences
• Current interval Duration
• Current Interval Timer
• Occurrences - Intervals, 1 through 96
• Duration - Intervals, 1 through 96
• Valid Intervals Total
• Occurrences, 24-hour value
• Duration, 24 -hour total
• 30-day switch occurrence history
3.2.11 Configuration Modes
Any time that the 1558A unit is initialized (power removed,
then reapplied), all key configuration data is read by the
1558A CPU and implemented based upon the particular
boot mode options selected by the user (see Installation Sec-
tion for additional information). The four possible BOOT
mode configurations are described below:
1)
Boot from Switches - At power up, the 1558A CPU
reads the values set at the rear panel option switches and
configures the unit per those switch settings.
2)
Boot from Manager - At power up the CPU sends a
message to the 1559 APS manager for a download of 1558A
unit configuration information. Note that this mode requires
that a 1559 site manager be installed.
3)
Boot from RAM - At power up, the 1558A CPU reads
the unit configuration from the battery backed RAM data.
4)
Boot from ROM - At power up, the 1558A CPU reads
the factory firmware default values from ROM. The factory
default ROM configuration option settings are:
• Block data link, both directions
• Regenerate CRC6, both directions
• Slave operation
• B8ZS line coding, both directions
• ESF framing, both directions
• Revert mode, disabled
• Availability timer set to 60 seconds
• Errored seconds set to 20
• Consecutively errored seconds set to 2
• Loss of frame set to enabled
• Loss of signal set to enabled
3.3
Front Panel Controls & Indicators
The front panel of the APS unit contains several LED indi-
cators, a SUPV access port, a path select switch, and several
bantam test access jacks. The following paragraphs briefly
describe the operation of these items (refer to
Figure 3-2
and the 1558A Configuration at the end of this manual).
