Hi .. my laser is leaving a trace between letters - like joined up writing !!

..does anyone know please of an NC generating software that caters for laser machine - or how do I tweek settings in my current ACE converter [DXF to NC code] to generate m-code with "S" command which switches [ so I understand] the laser OFF between letters - thanxx - or does it just "de-focus between burns - and I need to fettle THAT ?