Omron NT21 Reference Manual page 100

Memory Tables
Reference:
1, 2, 3...
84
If the allocated bits of multiple bit memory table entries come ON at the same
time, the bit memory table entry with the smallest number takes priority.
Alarm List/History Function
When the status of the host bit allocated for a bit memory table entry changes to
1 (ON), the contents of the character string memory table entry (message), and
the image/library data set for that bit memory table entry are displayed (this is the
alarm list function). In order to use the alarm list function, it must be registered for
the screen in advance. If more than one bit memory table entry is set for the
alarm list function, those with smaller bit memory table entry numbers are given
display priority, therefore it is possible to assign an order or priority to displayed
messages.
If registration in the alarm history is designated, the time when the status of the
host bit allocated for the bit memory table entry changes to 1 (ON) is recorded in
the alarm history (alarm history function).
For details, refer to 2-11 Alarm List, Alarm History (page 182).
Character string
memory table entry 32
Image/library
data 102A
Message (character string memory table entry 32)
and image/library data (102A) set for bit memory
table entry 14.
Operation when Using the Alarm List/History Function
The operation when using the alarm list/history function is as follows:
S For the alarm list function, display is in ascending order of bit memory table
entry numbers. For the alarm history function display is in occurrence order
(from newest record/from oldest record) or frequency order.
S With the alarm list function, when the host bit allocated for the bit memory table
entry returns to 0 (OFF) during display, the message and image/library data is
automatically cleared.
1. When the status of a bit memory table entry changes to 1 (ON), the contents
of the set character string memory table entry are displayed as a message.
Contents of character string memory table entry
set for the bit memory table entry whose status
has changed to 1 (ON).
PROCESS 3 STOPPED
WATER TANK OVERHEATING
Character string memory table entry 50
Image/library data 0F51
Character string memory table entry 32
Image/library data 102A
Character string memory table entry 54
Image/library data 12AB
Section 2-3
Bit PC
No. 13
0
1 (ON)
0
No. 14
0
No. 15
If an alarm list with multiple lines is
created, alarms are displayed in
ascending order of bit memory table
entry numbers.
If the bit memory table entries are set in
ascending order of priority, the display
will also be arranged in accordance
with the order of priority.