Expressions

An expression can consist of the following elements:

• Numeric and string literals

• Global and local variables

• Infix operators and functions

• Commas and brackets

In the same way, parentheses (if not used for identifying comments) and braces can be used for structuring of expressions. This means that the expression (1 + 2} * 3 is permitted.

A space after the G address is required only if SMC_ReadNCFile2 would not recognize it as an independent token (example: X abs{-2} instead of Xabs{-2}.).

In contrast with ST, single-position functions do not necessarily have to be called with parentheses (example: sin 3).

When parsing, each partial expression is assigned one of the three types: BOOL, LREAL, or STRING. Accordingly, each Infix operator and each function expects a specific sequence of argument types for which noncompliance (wrong type, too few, or too many arguments) returns an error.

Restrictions:

• Block numbers have to be numeric literals.

• For technical reasons, jump markers (x in L!x) must not contain any local variables.

See also

• Jump

• Using Variables

N01 G36 O$var$ D concat{'prefix_', concat{$var$, '_suffix'}}
N02 G1 X$var$ + sin{pi + 3 * #locvar}
N03 G20 L0 K NOT {myfun{$var$, expt{2, #locvar}} XOR myfun{0, 0}}

It is possible to add your own functions or overwrite an existing implementation. (When parsing the G code, functions are searched for first in the user functions.)

To do this, the interface SMC_NC_IFunction has to be implemented, and a global instance of the corresponding POU has to be accessible to SMC_NCTokenParser by means of the SMC_NC_GFunctionTable structure.

The enumeration SMC_GVar_Type is used for the return type and argument types. The entry contained there T_OTHER can be used as a placeholder for a type. When parsing, the system checks that all arguments that correspond to a T_OTHER in the signature have the same type. The type does not matter.

When possible, the exact position of the defective token and its length are issued in syntax errors. The error position is listed in SMC_ReadNCFile2.errorPos.

See also

• DIN 66025 Fundamentals