Omron NT620C, Operation Manual

Page: 194 / 337

4-11 Section Alarm List & History Display Functions
182
Recording Format of Alarm History
For the alarm history, the following data is recorded in the memory concerning
the contact that turns “1” (ON).
- Contact number
- Date and time of occurrence
- Message set in the bit memory table (the contents of the character-string
memory table)
Maximum Number of Alarms to be Recorded
The number of alarms to be recorded is up to 256 in the order of occurrence, or up
to 255 for each alarm message in the order of frequency.
Data recorded is backed up by a battery, so it is not lost even when the power
supply is turned OFF.
Reference When the voltage of the battery in the NT620S/NT620C drops, the recorded
data cannot be retained reliably.
How to deal with alarm recording in the order of occurrence when the number of
alarms capable of being recorded is exceeded is determined by the “Alarm First-
in First-out” setting of the “System Memory” of the support tool as follows:
ON: Old history is cleared and new history is recorded.
OFF: Alarms in excess of 256 are not recorded (new alarms are discarded).
In order to clear (initialize) the alarm history, the memory is initialized (Refer to
page 67).
The alarm history can also be cleared using bit 11 of the “PT status control bits.”
(Refer to page 237.)
How to Make Sure of Alarm History
The alarm history can be displayed by the NT620S/620C during operation by set-
ting an area and displaying method when creating a screen data with the support
tool.
There are two displaying methods: in the order of occurrence and frequency.
•
In the order of occurrence
The alarm history is displayed in the order that a contact becomes “1” (ON). As
more detailed information, date and time of occurrence can be displayed si-
multaneously.
Check the remote I/O
transmission line!
Abnormal remote I/O 94/06/06 16:02
Abnormal high function unit 94/06/07 09:21
Cycle time over 94/06/17 15:44
Occurrence of
transmission
abnormality