Omron NT21 Reference Manual page 48

Communications with the Host
PT Status Control Area
(PC PT)
PT Status Notify Area
(PT to PC)
32
Alarm History (Bit Memory Table) (page 182)
Allocated: Bit
PT
Water temp. high
Character string memory table entry
Alarm history
134
Bit memory table entry 52
Character string memory table entry 134
Alarm history record data
The PC bit allocated to the bit memory table entry for which the history property
has been set is continually monitored: when the bit turns ON (1), the time, the
number of times, and the contents of the character string memory table entry
registered for the bit memory table entry are recorded in the alarm history record
data.
This record data can be displayed as the alarm history.
The PT status control area is used to control the PT status. When data is written
to this area in the PC, the PT reads the contents and operates according to the
contents.
Example of PT Status Control Area Application
When data is written to the PT status control area, the PT operates as shown
below (page 52).
PT
Screen 3 display
Continuous
buzzer
sound
Numeral memory table entry 50
Copy
Numeral memory table entry 7
The PT status notify area is used to notify the changes in the PT status.
When the PT status changes, the change is written to this area in the PC. By
reading the data from this area, the PT status can be checked.
PC
015012
Water temp. high
Bit 015012
PC
PT status control area
Section 1-4
1
0003
Screen switch setting
0050
Memory table entry
1007
Copy setting
A000
PT status control bits
System reserve