The 16-bit variables %MWi are described as WORD, but they always work as INT => signed 16-bit value range (-32768, +32767).
=> this means the value 45000 in a %MW is seen as -20536, and it is not possible to enter any value >32767 from the animation table.

• For local variables, if we know they are positive values with some maximum >32767 (it’s definition of UINT) then it is necessary to use a 32-bit format %MD instead a %MW into the whole program.

• For variables (IN/OUT) exchanged with other devices, sometimes there is no choice, the 16-bit format of the variable is defined/fixed with the third party device.

Example: The object %MWa is written into the M221 over a Modbus communication, and you need to use this value inside the M221 application, within arithmetic operations.

In that case, it is necessary to use in addition to the initial %MWa, another variable %MDb and an operation to transform the %MWa into %MDb by keeping the initial positive UINT value.
For that purpose, you have to use the following operation:
%MDb := CONCATW (%MWa, 0)              // it’s forcing the upper word being 0
Result is :

If %MWa=2000;  then %MDb=2000

If %MWa=45000 (-20536 seen n the animation table);  then %MDb=45000

Опубліковано для:Schneider Electric Україна