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NDA-24300 CHAPTER 2
Page 15
Issue 1
SYSTEM MAINTENANCE OUTLINE
2.5 Fault Detecting Function
The system finds a fault by its fault detecting circuit and the fault detecting program. Once a fault occurs,
the system initiates a remedial action such as system changeover, make-busy setting, or restart processing
by the automatic diagnosis function. This action reduces the influence of the fault so that system servicing
may be minimized. The result of the process taken and the fault situation are indicated for equipment
concerned.
Among the faults, those related to speech path (noise, one-way speech, speech inability, etc.) are not
detectable. Since these fault reports are to be obtained from a station or operator, periodic trunk tests must
be performed without failure to detect the faults related to speech path.
Figure 2-13 shows an outline of fault detection, and Figure 2-14 shows a block diagram of fault detection.
Figure 2-13 Fault Detection General Diagram
Fault Occurrence
Indication
Information
Collection and Diagnosis
Example of Faults
IOC
CPU
EMA
Display of
System Messages
Indication of
Alarm Lamps
on TOPU
Fault of line/trunk card
TSW write failure,
Fault of clocks, etc.
Abnormal temperature,
power supply failure,
fuse blowing, etc., within
the equipment frame
NEC
NEAX 2400 IMS