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4.4 Contacts
A contact is used to monitor the state of a reference address. Whether the contact passes power
flow depends on positive power flow into the contact, the state or status of the reference address
being 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
Continuation
Contact
Fault Contact
High Alarm
Contact
Low Alarm
Contact
No Fault
Contact
Normally Closed
Contact
Normally Open
Contact
Transition
Contacts
GFK-2950C
Mnemoni
Contact Passes Power to Right...
c
CONTCON if the preceding continuation coil is set ON
FAULT
if its associated BOOL or WORD variable has a point fault
HIALR
if the high alarm bit associated with the analog (WORD) reference is
ON
LOALR
if the low alarm bit associated with the analog (WORD) reference is
ON
NOFLT
if its associated BOOL or WORD variable does not have a point fault
NCCON
if associated BOOL variable is OFF
NOCON
if associated BOOL variable is ON
NEGCON
(negative transition contact) if BOOL reference transitions from ON
to OFF. Updated every time it is called.
NTCON
(negative transition contact) if BOOL reference transitions from
ON to OFF. Updated once per scan.
POSCON
(positive transition contact) if BOOL reference transitions from OFF
to ON. Updated every time it is called.
PTCON
(positive transition contact) if BOOL reference transitions from OFF
to ON. Updated once per scan.
February 2018
Chapter 4. Ladder Diagram (LD) Programming
91
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