Mitsubishi Electric MELCEC Q Series User Manual page 86

4. CPU MODULE
Internal timer 0
The operation of M9077 above is shown below:
(a) When 5ms is set at D9077 (The scan time is shorter than the setting value.)
1st scan 2nd scan
4ms 3ms
ON
M9077
OFF
Turns OFF because Remains OFF because
accumulation time accumulation time
is 4 ms.
4 0
In the diagram above, M9077 is ON at the first scan so that the instruction is
executed. At the beginning of the second scan, the accumulation time does not
reach 5 ms. As a result, M9077 turns OFF, the accumulation time is cleared, and
the instruction is not executed. At the end of the second scan, the accumulation
time does not reach 5 ms, so that M9077 remains OFF and the instruction is not
executed. At the end of the third scan, the accumulation time exceeds 5ms. As a
result, M9077 turns ON, the accumulation time is cleared, and the instruction is
executed at the forth scan. At the end of the forth scan, the accumulation time
exceeds 5ms, so that M9077 remains ON and the instruction is executed at the
fifth scan. At the end of the fifth scan, the accumulation time does not reach 5ms
so that M9077 turns OFF. The accumulation time is cleared and the instruction is
not executed at the sixth scan.
(b) When 5ms is set at D9077 (The scan time is longer than the setting value.)
1st scan
10ms
ON
M9077
Remains ON because
accumulation time
is 10 ms.
Internal timer 0
10
In the diagram above, M9077 is always ON when the scan time is always longer
than the setting value (D9077).
The following program example executes the FROM/TO instruction in the unit of
several seconds using M9077 and D9077 above.
M9036
M9077
FROM
*1 The setting range for the sequence accumulation time is 1 to 255ms (default: 5ms).
The value in D9077 should be in the range between 1 and 255. Otherwise, the value in D9077
is reset to 0 and M9077 is always OFF.
*2 If the instruction signal for the FROM/TO instruction is a pulse signal, the interlock with M9077
may mask the FROM/TO instruction, disabling execution. In such a case, keep the instruction
signal once in the other device.
*3 If execution order is set to the FROM/TO instruction, adding M9077 may change the
execution order. In such a case, do not use M9077, and make the execution interval of the
FROM/TO instruction longer with a user program.
3rd scan 4th scan
7ms
ON
Turns ON because
accumulation time
is 3 ms. is 10 ms.
3 10 0
2nd scan
10 ms
Remains ON because
accumulation time
is 10 ms.
0 10 0
MOV K5
H0 H1000 D0
4 - 40
5th scan 6th scan
5ms 4ms
OFF
Remains ON because Turns OFF because
accumulation time accumulation time
is 5 ms. is 4 ms.
5 0 4 0
3rd scan 4th scan
10 ms 10 ms
Remains ON because
accumulation time
is 10 ms.
10 0
D9077 Sets the accumulation time as 5ms.
Executes the FROM instruction
only when the interval between
sequence scans becomes 5ms
K10 or more. (Executes it at first scan.)
5ms
Turns ON because
accumulation time
is 10 ms.
5 0
Remains ON because
accumulation time
is 10 ms.
10 0