SMAR MB-700, User Manual

Page: 109 / 116

Technical Specifications
C.3
•
Data allocation for Swapped Unsigned32 data type (little-endian)
Modbus
Address
Data
40001 1234
40002 5678
Scale Conversion
The Blocks that support Scale conversion are listed below:
•
CCSM
EU_ADDRESS_A/EU_ADDRESS_B
•
CCCM
EU_ADDRESS_IN1 a EU_ADDRESS_IN2
EU_ADDRESS_OUT1 a EU_ADDRESS_OUT2
•
CCDL
EU_ADDRESS_A1
The scale conversion for Modbus protocol has two purposes:
•
Conversion from an internal analog value of block to a Modbus value in Engineering Units;
•
Conversion from a Modbus analog value to an internal value of block in Engineering Units.
The scale parameters are composed by the following items:
•
FROM_EU_100% - it defines the high value of the input unit (actual data unit);
•
FROM_EU_0% - it defines the low value of the input unit (actual data unit);
•
TO_EU_100% - it defines the high value of the output unit (data unit desired by user);
•
TO_EU_0% - it defines the low value of the output unit (data unit desired by user).
OBSERVATION
There are many different structure data that have scale conversion; therefore they follow the same
conversion procedure.
A = (TO_EU_100% - TO_EU_0%)/(FROM_EU_100% - FROM_EU_0%)
B = TO_EU_0% - A*FROM_EU_0%
Y=Ax+B
from_EU_0%
To_EU_0%
To_EU_100%
from_EU_100%
X
Y
Where x is the variable read from the input slave device and Y is the output variable.