Mitsubishi Electric MELSEC-L02SCPU User Manual page 201

(1) Counter type
Select the high-speed counter type.
• Linear counter: Counts pulses within the range of -2147483648 to 2147483647.
• Ring counter: Counts pulses within the range between the ring counter upper limit value and the lower limit
value.
(a) Operations of the linear counter
This counter type can be used with any counter functions available in the normal mode.
CH1 current value (SD1880 and SD1881)
CH1 underflow detection flag (SD1882.b1)
CH1 overflow detection flag (SD1882.b2)
CH1 Preset command (SM1893)
No.
When CH1 Current value (SD1880, SD1881) becomes smaller than the lower limit (-2147483648) during counting down, "detection
1) (1)" is stored in the underflow detection flag (SD1882.b1). Even if an additional pulse is inputted, the CH1 Current value (SD1880,
SD1881) remains at the lower limit (-2147483648).
When performing preset of the current value by turning on the CH1 Preset command (SM1893) or other methods, "No detection
2)
(0)" is stored in the underflow detection flag (SD1882.b1). The value is preset to "0" in the above chart. And then, counting restarts.
When CH1 Current value (SD1880, SD1881) becomes larger than the upper limit (2147483647) during counting up, "detection (1)"
3) is stored in the overflow detection flag (SD1882.b2). Even if an additional pulse is inputted, the CH1 Current value (SD1880,
SD1881) remains at the upper limit (2147483647).
When presetting the value by turning on the CH1 Preset command (SM1893) or other methods, "No detection (0)" is stored in the
4)
overflow detection flag (SD1882.b1). The value is preset to "0" in the above chart. And then, counting restarts.
• Errors of the linear counter
When the overflow error or underflow error is detected, "Over/underflow error (CH1 Error code: 3100)"
occurs.
2147483647
0
-2147483648
1) Underflow
ON
OFF
OFF
OFF
Description of operation
CHAPTER 8 HIGH-SPEED COUNTER FUNCTION
3) Overflow
ON
ON
2)
t ≥ 2ms
4)
t ≥ 2ms
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