Emerson Micro Motion 3711, Configuration And Use Manual, Page: 149 / 234

Configuration and Use Manual 141
Modbus Interface
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Float scaling
Some Modbus hosts cannot process floating-point values. Float scaling allows:
• Conversion of Model 3711 floating-point values to integers for processing by the Modbus host
• Conversion of host integer values generated to floating-point for processing by the
Model 3711
The following equations are used:
12.5.2 Datatype conversions
Specific datatype conversions can be specified for Modbus point data and for history data. Conversion
codes are listed and defined in Table 12-5.
For conversions involving floating-point values, this list assumes that the exponent is in byte 0 and the
mantissa is in bytes 1, 2, and 3.
ScaleValue
AnalogValue AnalogLow
–
( )
ScaleHigh ScaleLow
–
( ) ×
AnalogHigh AnalogLow –
( )
---------------------------------------------------------------------------------------------------------------------------------------------------- ScaleLow + =
Ana Value log
ScaleValue ScaleLow –
( )
Ana High log Ana L log ow –
( ) ×
ScaleHigh ScaleLow –
( )
-------------------------------------------------------------------------------------------------------------------------------------------------------- Ana Low log + =
FloatRange FloatScaleHighValue FloatScaleLowValue
– =
IntegerRange IntegerScaleHighValue IntegerScaleLowValue – =
AdjustedFloatValue OriginalFloatValue FloatScaleLowValue
– =
Integer
IntegerRange AdjustedFloatValue
×
FloatRange
---------------------------------------------------------------------------------------------- IntegerScaleLowValue + =
AdjustedIntegerValue OriginalIntegerValue IntegerScaleLowValue – =
Float
FloatRange AdjustedIntegerValue
×
IntegerRange
---------------------------------------------------------------------------------------------- FloatScaleLowValue + =
To convert floating-point values to integers
To convert integers to floating-point values
FloatRange FloatScaleHighValue FloatScaleLowValue – =
IntegerRange IntegerScaleHighValue IntegerScaleLowValue – =