I have some PLC CQM1H and CPM1A that protected by password. You know 4 digit password activated by AR ... (i forgot it). Few years a go i knew a man which can break this code. Unfortunatelly he's unreachable right now, dunno where he is. Please help us here, if anyone know how to break this code? or .. minimal, how to make breaking process become easier because we need to do modification at this machine and the engineer already sign out. :( anybody know?