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(f) When using multiple timers
When using multiple timers to update the respective current values at execution of each OUT T
pay attention to the ladder sequence.
For example, to create an on/off ladder using two timers, refer to examples shown in Figure 9.28.
[Correct ladder example]
Coil of T1 is turned on one scan after T0 is turned on.
T0
T1
T0
Coil of T0
Contact
of T0
Current
value of T0
Coil of T1
Contact
of T1
Current
value of T1
[Incorrect ladder example]
Coil of T1 is turned on within the same scan in which T0 was turned on.
T1
T0
T0
Coil of T0
Contact
of T0
Current
value of T0
Coil of T1
Contact
of T1
Current
value of T1
9 - 26
K10
T1
Measures for one second after T0 is turned on.
K10
T0
Measures for one second when T1 is off.
M0
Alternates on and off every second.
OUT T1
OUT T1
OUT T0
OUT T0
END processing
END processing
ON
OFF
OFF
0
0
0
1
One second
OFF
OFF
K10
Measures for one second when T1 is off.
T0
K10
Measures for one second after T0 is turned on.
T1
Alternates on and off every second.
M0
OUT T0
OUT T0
OUT T1
OUT T1
END processing
END processing
ON
OFF
OFF
0
0
0
1
9
One second
OFF
OFF
Figure 9.28 On/off ladder using two timers
OUT T1
OUT T1
OUT T1
OUT T0
OUT T0
OUT T0
END
END processing
END processing
processing
ON
9
10
ON
0
0
0
1
One second
OUT T0
OUT T0
OUT T1
OUT T1
END processing
END processing
ON
10
ON
0
1
1
2
900ms
Because the current value is updated in the scan where
T0 is timed out, the count starts from 1 or larger value.
OUT T1
OUT T1
OUT T0
OUT T0
END
END processing
processing
OFF
OFF
10
0
OFF
ON
OFF
9
10
10
0
OUT T0
OUT T0
OUT T1
OUT T1
END
END processing
processing
OFF
OFF
10
0
OFF
ON
OFF
9
10
10
0
instruction,
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