Expression is used with scripts, e.g. Expr.txt. Such files contain script code which is evaluated by PlanetCNC TNG expression evaluator.
It can be very practical for PLC type applications where periodical evaluation is necessary or for program events.
Expr.txt file can contain and use vast array of expression functions, parameters and other commands supported by PlanetCNC TNG.
Expr.txt file is located in the profile folder of TNG software.
Profile folder can contain multiple Expr.txt files. Specific Expr file naming convention is available for better distinction. e.g.: Expr_Semaphore
If multiple expr files use same function, then function will be called first from the first file and only then with the next file.
Local variables(e.g. name convention of local variables: red_light, global variables: _red_light ) have scope only within the parent Expr file.
Each Expr file contains functions that are marked with symbol #.
Each function begins with symbol # and ends with the next # symbol.
Each expr file can use built-in functions that are related with program events