Level Alarms
(Original Document)
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Description
This function monitors the progress of the process value by comparing its value to the 4 following thresholds: PV_LL, PV_L, PV_H and PV_HH.
Each alarm is associated to a status bit.
These alarms are controlled by a fixed hysteresis of 1% in relation to the scale defined in the loop's global parameters.
Alarms for crossing threshold PV_H or PV_L:
Parameters
Input Parameter:
Parameter
Symbol
Type
Thresholds
Default Value
R/W
Process value
PV
REAL
-3.4 E38 / 3.4E38
/
R
Internal parameters:
Parameter
Symbol
Type
Thresholds
Default Value
R/W
Very low threshold
PV_LL
REAL
-3.4 E38 / 3.4E38
5.0
R/W
Low threshold
PV_L
REAL
-3.4 E38 / 3.4E38
5.0
R/W
High threshold
PV_H
REAL
-3.4 E38 / 3.4E38
95.0
R/W
Very high threshold
PV_HH
REAL
-3.4 E38 / 3.4E38
95.0
R/W
Output parameters:
Parameter
Symbol
Type
Thresholds
Default Value
R/W
Very low limit
STS_PV_LL_LIM
EBOOL
/
/
R
Low limit
STS_PV_L_LIM
EBOOL
/
/
R
High limit
STS_PV_H_LIM
EBOOL
/
/
R
Very high limit
STS_PV_HH_LIM
EBOOL
/
/
R
Or alarms (*)
STS_ALARMS
EBOOL
/
/
R
(*) Or bit logic of alarms upon crossing threshold and alarms on deviation.
Execution Monitoring
The monitoring of the parameters is integrated into the error management of the process value branch.