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6-4SectionMemory Initialization
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6-4-3 Initializing Alarm History Record Data
The alarm history record function continually checks the status of host bits that
have been designated in advance with a bit memory table, and records the time
when any of the bits is set to 1 (comes ON), and the number of times that each bit
comes ON.
The maximum number of records is 256 for sort by occurrence (order of error
occurrence) and 255 for sort by frequency (order of the number of times each
error has occurred).
Use the alarm history record initialization function to reset the alarm history re-
cord data to 0, for example when the screen data has been changed, etc. Also, if
Screen (Use Ring Buffer) under History Setting in the PT Environment Settings –
System Settings has not been checked, no more records will be stored after the
maximum number of records has been kept, and therefore the records must be
periodically initialized. If Screen (Use Ring Buffer) is checked, when the maxi-
mum number of records is reached the oldest record is deleted and the newest
data is recorded.
Reference: The NT31/NT31C also allows the alarm history record data to be initialized by
controlling the PT status control area from the host. For details, refer to 2-2-1 PT
Status Control Area in the Reference Manual.