Use pulse catch to import pulse without setting the start and stop flags.
The pulse catch detect flag shows the pulse catch detection state under the CH special I/O state in the system variable (#L_ExIOSpCtrl). The watch bit will differ, depending on the CH to which you allocate the pulse catch.
#L_ExIOSpCtrl
If the 1st bit in the CH is 1, the pulse input has been detected. If it is 0, the input has not been detected.