National Instruments BridgeVIEW User Manual

Chapter 3

Tag Configuration

3-26

© National Instruments Corporation

The next sections explain how to scale data. Often your application needs 
BridgeVIEW to manipulate the raw data used in the device server to put it 
in a form, called engineering units, suitable for the operators. The following 
sections describe the options for individual data types.

Note

Eng Zero 
Scale

analog

Determines the zero scale (minimum) value used by the 
BridgeVIEW Engine and the user application for a tag. 
Engineering Zero Scale must be less than Engineering Full Scale. 

Units

analog

Determines the engineering units for a tag. Examples include 
degrees Celsius, liters, and kilograms. 

Scaling

analog, 
discrete, 
bit array

Determines the type of scaling algorithm to be used for a tag. 
The scaling methods differ according to tag data type. You can 
configure analog tags for linear or square root scaling, discrete 
tags for invert scaling, or bit array tags for mask scaling. All tags 
can be configured for no scaling.

Coerce

analog

Determines whether to coerce data so that it is valid for the target. 
If scaling to output, the value must be within the raw (device 
server) range. If scaling to input, the value must be within the 
engineering (HMI) range. 

Scaling Invert 
Mask

bit array 

Determines which bits are inverted for a bit array tag. Bits in 
the mask that are 

1

 are inverted; bits that are 

0

 are not inverted. 

The default mask is 

0

, indicating none of the bits are inverted. 

In bit-wise logic terminology, the Engine performs an XOR 
with the Invert Mask to produce the scaled value. 

Scaling Select 
Mask

bit array

Determines which bits are used for the bit array tag. Bits in 
the mask that are 

1

 have their values passed through to the 

RTDB; bits that are 

0

 are set to zero, regardless of the value 

received from the server. In bit-wise logic terminology, 
the Engine performs an AND with the Select Mask to 
produce the scaled value. 

Table 3-5.  Scaling Configuration Attributes (Continued)