Chapter 4. Ladder Diagram (LD) ProgrammingGFK-2950C February 2018 914.4 ContactsA contact is used to monitor the state of a reference address. Whether the contact passes powerflow depends on positive power flow into the contact, the state or status of the reference addressbeing monitored, and the contact type.A reference address is ON if its state is 1; it is OFF if its state is 0.Contact Display MnemonicContact Passes Power to Right...ContinuationContactCONTCON if the preceding continuation coil is set ONFault Contact FAULT if its associated BOOL or WORD variable has a point faultHigh AlarmContactHIALR if the high alarm bit associated with the analog (WORD) reference isONLow AlarmContactLOALR if the low alarm bit associated with the analog (WORD) reference isONNo FaultContactNOFLT if its associated BOOL or WORD variable does not have a point faultNormally ClosedContactNCCON if associated BOOL variable is OFFNormally OpenContactNOCON if associated BOOL variable is ONTransitionContactsNEGCON (negative transition contact) if BOOL reference transitions from ONto OFF. Updated every time it is called.NTCON (negative transition contact) if BOOL reference transitions fromON to OFF. Updated once per scan.POSCON (positive transition contact) if BOOL reference transitions from OFFto ON. Updated every time it is called.PTCON (positive transition contact) if BOOL reference transitions from OFFto ON. Updated once per scan.
