IDEC WindSRV - Manual (Page 70)

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Note: User-defined tags support scaling.
Tag Scaling
This server supports Tag Scaling, which allows raw data from the device to be scaled to an appropriate range for the
application. To enable Tag Scaling, select either Linear or Square Root. Scaling cannot be enabled if None is checked.
The formula for both Tag Scaling types are shown in the table below.
Type Formula for Scaled Value
Linear
(((ScaledHigh - ScaledLow)/(RawHigh - RawLow))*
(RawValue - RawLow)) + ScaledLow
Square root
(Square root ((RawValue - RawLow)/(RawHigh -
RawLow))*(ScaledHigh - ScaledLow)) + ScaledLow
The Raw Value Range settings are used to specify the range of raw data from the device. The raw value High setting
must be greater than the Low setting. The valid range depends on the raw tag value's data type. For example, if the
raw value is Short, the valid range of the raw value would be from -32768 to 32767.
The Scaled Value Range settings are used to specify the range of the resulting scaled value.
Parameter Definition
Data Type
A scaled value is usually assumed to result in a floating-point value, although the server
does not make that assumption. The data type can be set to any valid OPC data type. This
gives users the ability to scale from a raw data type such as Short to an engineering value
with a data type of Long if needed. The default scaled data type is Double.
High and Low
The scaled value High must be greater than the scaled value Low. The valid range depends
on the data type of the scaled value. For example, if the scaled data type is set to Long,
then the valid range would be -2147483648 to 2147483647.
Clamp The raw data from the device may exceed the range that has been specified for the raw