SCALE
Linearly scales the input value (PV) according to the low input (IPmin), high input (IPmax), low output (OUTmin) and high output (OUTmax) values. The input value is bound to the range set by IPmin and IPmax.
OUT = ( ( (Min(Max(PV, IPmin), IPmax) - IPmin) / (IPmax - IPmin) ) * (OUTmax - OUTmin) ) + OUTmin
Parameter values for the SCALE function block:
Parameter | Data Type | Description | ||
|---|---|---|---|---|
PV | REAL | Input value | ||
IPmax | REAL | High input REAL value. Infinity or Not a Number (NaN) values are not supported by
this input. When PV > IPmax, scales PV using the IPmax value. | ||
IPmin | REAL | Low input REAL value. Infinity or Not a Number (NaN) values are not supported by
this input. When PV < IPmin, scales PV using the IPmin value. | ||
OUTmax | REAL | High output REAL value. Infinity or Not a Number
(NaN) values are not supported by this input. | ||
OUTmin | REAL | Low output REAL value. Infinity or Not a Number
(NaN) values are not supported by this input. | ||
OUT | REAL | When PV is within the range set by IPmax and IPmin, OUT scales the input
value. When PV is <= IPmin, the value set is OUTmin When PV is >= IPmax, the value set is OUTmax | ||
LIMIT | BOOL | Indicates PV is out of range. When FALSE, PV is within the range set by IPmin and IPmax. When TRUE, PV is out of range. | ||
TIP:
Loss of precision may occur when using this
function.
When IPmax < IPmin, the function block assumes that the values are reversed and swaps them. The
ERRSTAT
Reversed error counter increments each time the function has to swap the parameters.When IPmax = IPmin, OUT sets to the value of OUTmin, LIMIT sets to FALSE and the
ERRSTAT
ZeroDivide error counter increments.When PV is Not a Number (NaN) value, OUT sets to the value of OUTmin, LIMIT sets to FALSE and the
ERRSTAT
Param error counter increments.When an overflow or underflow condition occurs during execution of the function block, OUT sets to OUTmax or OUTmin respectively, LIMIT sets to FALSE and the corresponding
ERRSTAT
Overflow or Underflow error counter increments. If both occur, OUT sets to OUTmin, LIMIT sets to FALSE and both Overflow and Underflow error counters increment.Function Block Diagram Example
Structured Text Example
SCALE(Input, MaxValue, MinValue, OutMaxV, OutMinV); ScaledValue := SCALE.OUT; Result := SCALE.LIMIT;
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