Specifications

X723-300151 6-21 Issue 2
The interrelation between the four main fault classes is shown below.
System (equipment)
faults
PCM transmission
faults
Synchronisation
faults
Data path
faults
From this it can be seen that the correct sequence for clearing network
problems is:
1. Check and clear all system faults at all nodes in the network.
2. Check and clear all PCM transmission faults in the network. Note
that where a transmission fault could be caused by either a PCM
equipment or by the transmission link, application of test loops can
deduce the area of fault. Test loops can be applied by either using test
facilities built-into equipments, or by using external cable connections
to loop the PCM paths.
3. Check and clear all synchronisation faults.
4. Check data path routing and data circuit connections. Circuit test
loops can be configured to assist in the testing of the external data
connections and data synchronisation.
6.4 Built-in Test Facilities
The multiplexer built-in test facilities are accessed via the Maintenance
sub-menu. In each section below the numbers in brackets are the manual
section numbers to refer to for details of the command.
Installation/System Faults
To permit testing of the external alarm relay circuit each relay can be set
or cleared using the Maintenance - Alarm - Relay Set commands (6.2.6).
The Maintenance - Alarm sub-menu also allows control of the system
controller LEDs. When testing is completed relays and indicators will be
automatically reset to the correct current status.