60 Rockwell Automation Publication 1756-RM003N-EN-P - October 2011
Chapter 1 FactoryTalk Alarms and Events Logix-based Instructions (ALMD, ALMA)
ROCPosSeverity DINT Severity of the increasing rate-of-change condition. This does not affect processing of alarms by the
controller, but can be used for sorting and filtering functions at the alarm subscriber.
Valid = 1...1000 (1000 = most severe; 1 = least severe).
Default = 500.
ROCNegLimit REAL Limit for a decreasing rate-of-change in units per second. Detection is enabled for any value > 0.0 if
ROCPeriod is also > 0.0.
Valid = 0.0...maximum possible float.
Default = 0.0.
ROCNegSeverity DINT Severity of the decreasing rate-of-change condition. This does not affect processing of alarms by the
controller, but can be used for sorting and filtering functions at the alarm subscriber.
Valid = 1...1000 (1000 = most severe; 1 = least severe).
Default = 500.
ROCPeriod REAL Time period in seconds for calculation (sampling interval) of the rate of change value. Each time the
sampling interval expires, a new sample of In is stored, and ROC is recalculated.
Rate-of-change detection is enabled for any value > 0.0.
Valid = 0.0...maximum possible float.
Default = 0.0.
Input Parameter Data Type Description
Output Parameter Data Type Description
EnableOut BOOL Enable output.
InAlarm BOOL Alarm active status. Set when any alarm condition is active. Cleared when all alarm conditions are
not active (normal status).
AnyInAlarmUnack BOOL Combined alarm active and acknowledged status. Set when any alarm condition is detected and
unacknowledged. Cleared when all alarm conditions are normal (inactive), acknowledged, or both.
HHInAlarm BOOL High High alarm condition status. Set when a High High condition exists. Cleared when no High High
condition exists.
HInAlarm BOOL High alarm condition status. Set when a High condition exists. Cleared when no High condition exists.
LInAlarm BOOL Low alarm condition status. Set when a Low condition exists. Cleared when no Low condition exists.
LLInAlarm BOOL Low Low alarm condition status. Set when a Low Low condition exists. Cleared when no Low Low
condition exists.
ROCPosInAlarm BOOL Positive rate-of-change alarm condition status. Set when a positive rate-of-change condition exists.
Cleared when no positive rate-of-change condition exists.
ROCNegInAlarm BOOL Negative rate-of-change alarm condition status. Set when a negative rate-of-change condition exists.
Cleared when no negative rate-of-change condition exists.
ROC REAL Calculated rate-of-change of the In value. This value is updated when the instruction is scanned
following each elapsed ROCPeriod. The ROC value is used to evaluate the ROCPosInAlarm and
ROCNegInAlarm conditions.
ROC = (current sample of In – previous sample of In) / ROCPeriod.
HHAcked BOOL High High condition acknowledged status. Set when a High High condition is acknowledged. Always
set when AckRequired is cleared. Cleared when a High High condition is not acknowledged.
HAcked BOOL High condition acknowledged status. Set when a High condition is acknowledged. Always set when
AckRequired is cleared. Cleared when a High condition is not acknowledged.
LAcked BOOL Low condition acknowledged status. Set when a Low condition is acknowledged. Always set when
AckRequired is cleared. Cleared when a Low condition is not acknowledged.
LLAcked BOOL Low Low condition acknowledged status. Set when a Low Low condition is acknowledged. Always
set when AckRequired is cleared. Cleared when a Low Low condition is not acknowledged.
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