Omron NE1A-SCPU01 - 07-2009 Operation Manual page 154

Common Functions
Note
120
(1) The Total ON Time Monitor function (Time) and Contact Operation
Counter function (Count) cannot be used simultaneously on one bit. Se-
lect one of these functions with the Maintenance Counter Mode Choice
setting.
(2) When the Maintenance Counter Mode Choice setting is changed, the col-
lected data (operations count or total ON time) will be cleared.
(3) These functions do not operate when the I/O power supply is OFF.
(4) The Total ON Time Monitor function checks whether the connected de-
vice is ON at about 1-s intervals. This function may not count the total ON
time precisely if the device is ON for intervals of less than 1 second.
■ Calculating the Total ON Time with 0.5-s ON Pulses
In figure A, the bit is actually ON for 0.5 s × 3 = 1.5 s, but the bit is ON just
once when the status is checked, so the total ON time is measured as 1 s.
Measured about 1 time/second
ON
OFF
0.5 s
Figure A
In figure B, the bit is actually ON for 0.5 s × 3 = 1.5 s, but the bit is ON twice
when the status is checked, so the total ON time is measured as 2 s.
Measured about 1 time/second
ON
OFF
0.5 s
Figure B
■ Calculating the Total ON Time with 1.5-s ON Pulses
In figure C, the bit is actually ON for 1.5 s × 2 = 3 s, but the bit is ON four times
when the status is checked, so the total ON time is measured as 4 s.
Measured about 1 time/second
ON
OFF
1.5 s
Figure C
Section 7-1