DEV_AL
Deviation alarm indicating the deviation of the process variable (PV) away from the set point (SP).
DEVhi = ( (PV - SP) >= DEVus)
DEVlo = ( (SP - PV) >= DEVds)
Parameter values for the DEV_AL function block:
Parameter | Data Type | Description |
|---|---|---|
PV | REAL | Input process variable. This value must be a REAL value. Infinity or Not a Number (NaN) values are not supported by this input. |
SP | REAL | Set point value. This value must be a REAL value. Infinity or Not a Number (NaN) values are not supported by this input. |
DEVus | REAL | Up-scale deviation parameter. This value must be a REAL value. Infinity or Not a Number (NaN) values are not supported by this input. |
DEVds | REAL | Down-scale deviation parameter. This value must be a REAL value. Infinity or Not a Number (NaN) values are not supported by this input. |
DEVhi | BOOL | TRUE when PV > SP by at least DEVus. |
DEVlo | BOOL | TRUE when PV < SP by at least DEVds. |
When an overflow condition occurs during execution, DEVhi sets to PV > 0, DEVlo to PV < 0, and the
ERRSTAT
Overflow error counter increments.Function Block Diagram Example
Structured Text Example
DEV_AL(Process1, SetPoint, upV, DownV); High := DEV_AL.DEVhi Low := DEV_AL.DEVlo
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