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MELSEC-Q
5 BASIC USAGE
5.2 Selecting the Counter Format
Select either linear counter or ring counter with the GX Developer intelligent function
module switch setting.
See Section 4.5 for details on the setting method.
5.2.1 Selecting the linear counter
(1) Linear counter operation
When the linear counter is selected, the count operation is performed between
-2147483648 (minimum value) and 2147483647 (maximum value).
The linear counter can be used in combination with the preset function and the
coincidence output function.
Overflow
Overflow
+ 2147483647
– 2147483648
Addition
Subtraction
Counter present value
0
(2) Overflow error
(a) When the counter format is linear counter, an overflow error occurs if the
present counter value exceeds -2147483648 (minimum value) during
subtraction or exceeds 2147483647 (maximum value) during addition.
(b) When an overflow error occurs, "1" is stored in CH
Overflow detection flag
(Un\G8, Un\G40), the counting stops, and the present value does not
change from -2147483648 or 2147483647 even if pulses are input.
(c) The overflow error can be cleared by performing the preset function.
When the preset function is performed, "0" is stored in CH
Overflow
detection flag (Un\G8, Un\G40) and the counting can be resumed.
(d) Occurrence of overflow error can be checked on the System Monitor window.
For details, refer to Section 9.1.