The io_function_block attribute has the effect that a function block, which is decorated with it, is available
in the device configuration for assignment to a channel in the I/O mapping. The function block is shown in the “Select Function Block” dialog.
The 'io_function_block_mapping' attribute has the effect in this kind of function block that a parameter is decorated
which is automatically used when mapping the function block to a device channel.
You can provide the attribute to multiple parameters of the function block. For I/O mapping, the first one is used automatically whose type matches the channel (input, output, data type).
Syntax:
{attribute 'io_function_block'}
{attribute 'io_function_block_mapping'}
Insert location: The line above the first line in the declaration of the function block, and in the line above the parameter declaration.
Example
{attribute 'io_function_block'}
FUNCTION_BLOCK Scale_Output_Int
VAR_INPUT
iInput : INT;
iNumerator : INT;
iDenominator : INT :=1;
iOffset : INT := 0;
END_VAR
VAR_OUTPUT
{attribute 'io_function_block_mapping'}
iOutput : INT;
END_VAR
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See also: ⮫ Select Function Block