Mitsubishi Electric MELSEC-L02SCPU User Manual page 220

The explanation in this section is based on the case where the Function Input Logic Setting is set to Positive Logic (default).
The execution timing of the count disable function and the preset function in the case of Negative Logic setting is as shown
below.
Negative logic setting
• Precautions
• The preset function is not available if CH1 External preset (phase Z) request detection (SM1886) is on.
(Only the count disable function is executable.) In this case, turn off this relay by turning on CH1 External
preset (phase Z) request detection reset command (SM1897).
• Provide a 2ms or more interval between the execution command establishment of the Preset value write
instruction (ICPREWR1(P)) and replacement with the preset value. If not, a preset value setting before
change may be stored in CH1 Current value (SD1880, SD1881).
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Counting stopped Preset value is set, and counting restarts.