Yaskawa DSD 406 - Manual (Page 101)

Glossary
97 Glossary
3/21/96
EPROM – Erasable Programmable Read Only Memory. An integrated circuit
that is usually used to hold the instructions for a microprocessor’s program.
Error – An abnormal condition considered less serious than a fault (see FAULT
definition). The difference between the two is that an error is recorded in the
NVRAM, but not announced on the CDUs. The declaration of a fault will cause
immediate display of the fault code number on the SCDU and the lighting of the
FAULT LED. Any abnormal condition, standard or custom (also see
STANDARD FAULT and CUSTOM FAULT definitions) may be declared as an
error, a fault or both. Each abnormal condition is given an initial default
classification as either an error, a fault, or both an error AND a fault. A special
CDU function is provided to override that initial default classification.
The declaration of an error places the error number assigned to that error at the
end of the Last Error List. This error list is of fixed length (16) and allows
display via the CDU of the latest errors (note this differs from the First Fault
List, which displays the oldest faults). In addition to the display of the error
code number, this error list also allows the display of the task number of the PAC
task generating the error (if the error was not generated by a PAC task, then task
number zero [0] is displayed) and a time stamp of when the error occurred.
Fault – An abnormal condition generally requiring corrective action. A fault is
considered to be a condition more serious than an error (see ERROR definition).
The difference between the two is that an error is recorded in the NVRAM, but
not announced on the CDUs. The declaration of a fault will cause immediate
display of the fault code number on the SCDU and the lighting of the Fault LED.
If multiple faults occur, the last declared fault is the fault displayed on the CDU.
A fixed number of faults (16) are recorded in order of declaration. This Fault
List may be reviewed by order of fault declaration via a special CDU function.
Once the Fault List is full, declaration of additional faults will not appear on the
Fault List until space on the list is made available. The same CDU function used
to display the Fault List may be used to clear from the list either all the faults or
individual faults. The FAULT LED will remain lit until all the faults have been
cleared from the Fault List.
Faults can be classified into two categories: “Standard” (see STANDARD FAULT
definition) and “Custom” (see CUSTOM FAULT definition).
In most cases, no action is taken when a fault is declared. In these cases, the
corrective action is the responsibility of the PAC program. In some cases,
however, the abnormal condition is so severe that corrective action must be
taken without regard to the PAC program (see SEVERE FAULT definition).
All defined abnormal conditions may be categorized as a fault or not a fault via a
special CDU function. Each of these conditions is given an initial default (i.e. it