The following table lists the system parameters for the Alarm Detection function block:
Parameter |
Units |
Description |
|---|---|---|
ALARM_HYS |
Percent or Percent of IN_SCALE |
The amount the alarm value must return within the alarm limit before the associated active alarm condition clears. If SCALE_ENABLE is not set, the raw value will not be scaled. ALARM_HYS is limited to 50% of scale. |
BLOCK_ERR |
None |
The summary of active error conditions associated with the block. The block errors for the Alarm Detection function block are: BadPV - the source of the block's process variable is bad. |
DEFAULT |
EU of IN_SCALE |
The value used for PV whenever IO_IN does not have a valid reference and the status of IN is Not Connected. If SCALE_ENABLE is not set, the raw value will not be scaled. |
DV_HI_ACT |
None |
The result of alarm detection associated with DV_HI_LIM. If DV_HI_ACT equals True, DV_HI_LIM has been exceeded. |
DV_HI_LIM |
EU of IN_SCALE |
The amount by which PV can deviate above SP before the deviation high alarm is triggered. The magnitude of DV_HI_LIM cannot be greater than the range of IN_SCALE. When this limit is exceeded, DV_HI_ACT is set to True. If SCALE_ENABLE is not set, the raw value will not be scaled. |
DV_LO_ACT |
None |
The result of alarm detection associated with DV_LO_LIM. If DV_LO_ACT equals True, DV_LO_LIM has been exceeded. |
DV_LO_LIM |
EU of IN_SCALE |
The amount by which PV can deviate below SP before the deviation low alarm is triggered. The magnitude of DV_LO_LIM cannot be greater than the range of IN_SCALE. When this limit is exceeded, DV_LO_ACT is set to True. Note that DV_LO_LIM is a negative number and is compared against PV – SP. If SCALE_ENABLE is not set, the raw value will not be scaled. |
ENABLE |
None |
The discrete input value and status that activates the alarm calculation. |
HI_ACT |
None |
The result of alarm detection associated with HI_LIM. If HI_ACT equals True, HI_LIM has been exceeded. |
HI_HI_ACT |
None |
The result of alarm detection associated with HI_HI_LIM. If HI_HI_ACT equals True, HI_HI_LIM has been exceeded. |
HI_HI_LIM |
EU of IN_SCALE |
The setting for the alarm limit used to detect the high high alarm condition. If SCALE_ENABLE is not set, the raw value will not be scaled. |
HI_LIM |
EU of IN_SCALE |
The setting for the alarm limit used to detect the high alarm condition. If SCALE_ENABLE is not set, the raw value will not be scaled. |
IN |
Determined by source or EU of PV_SCALE |
The analog input value and status. |
IN_SCALE |
None |
The high and low scale values, engineering units code, and number of digits to the right of the decimal point associated with IN or value from IO_IN. |
IO_IN |
None |
Defines the input DST for the I/O channel used for the PV. |
LO_ACT |
None |
The result of alarm detection associated with LO_LIM. If LO_ACT equals True, LO_LIM has been exceeded. |
LO_LIM |
EU of IN_SCALE |
The setting for the alarm limit used to detect the low alarm condition. If SCALE_ENABLE is not set, the raw value will not be scaled. |
LO_LO_ACT |
None |
The result of alarm detection associated with LO_LO_LIM. If LO_LO_ACT equals True, LO_LO_LIM has been exceeded. |
LO_LO_LIM |
EU of IN_SCALE |
The setting for the alarm limit used to detect the low low alarm condition. If SCALE_ENABLE is not set, the raw value will not be scaled. |
PV |
EU of IN_SCALE |
The process variable used in block execution and alarm limit detection. |
SCALE_ENABLE |
None |
Enables/disables scaling. |
SP |
EU of IN_SCALE |
The block's setpoint value. |