The LSCALC function block uses as many as 16 inputs and 16 outputs to evaluate its contained expression. In addition, the expression evaluator uses constants and module parameter references that you specify to evaluate the expression. Expressions can only reference parameters that are internal to the SIS module in which the LSCALC block is located. External references from LSCALC block expressions are not allowed. The calculated values are assigned to internal module references or block outputs for use as parameters or inputs to the control strategy in other blocks.
The inputs and outputs in the LSCALC function block are extensible parameters. The block default is two inputs and two outputs. You add inputs or outputs by selecting the function block diagram and clicking the right mouse button, clicking Extensible Parameters, and modifying the number of inputs and/or outputs. This creates additional input/output connectors for the block.
Expressions
Expressions are structured text in a specific syntax and are made up of operands, operators, functions, constants, and keywords. You write expressions using the Expression Editor.
The values of temporary variables in expressions are not preserved on download or restored on restart. Temporary variables start with a value of 0 (zero) on the first scan after a download or restart.