Mitsubishi Electric MELSEC-Q Series User Manual page 184

10 DEVICES
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Interrupt counters
(1) Definition
Interrupt counters are devices which count the number of interrupt factor
occurrences.
(2) Count processing
(a) The interrupt counter's present value is updated when an interruption
occurs. It is not necessary to create a program which includes an interrupt
counter function.
(b) Interrupt counter operation requires more than the simple designation of a
setting value.
To use the interrupt counter for control purposes, comparison instructions
(=, <=, etc.) must also be used to enable comparisons with the setting
value, with an internal relay (M), etc., being switched ON or OFF according
to the comparison result.
The figure below shows a sample program in which M0 is switched ON
after 10 interrupt inputs occur. (In this example, "C300" is the interrupt
counter No. corresponding to I0.)
= K10
(3) Setting the interrupt counter
(a) In order to use interrupt counters, at first interrupt counter No. setting must
be designated in the PLC system settings in the PLC parameter setting.
256 points are then allocated for interrupt counters, beginning from the "first
counter No." which is designated.
If C300 is designated as the first interrupt counter No., numbers C300 to
C555 will be allocated for interrupt counters.
C300 I0
C301 I1
C302 I2
C555 I127
(b) In order to use an interrupt counter, an "interruption permitted" status must
be established by E1 instruction at the main routine program.
C300
Interrupt counter (127 points)
Values corresponding to the interrupt counter No.
MELSEC-Q
M0
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