ISPSoft User Manual A is superior to function block B, function block B and function block C can not call function block A, but the POU of the program type can call function block A, function block B, or function block C. If function block A, function block C, and function B are not called by any POUs of the program type, they do not participate in the execution of the program, and the corresponding function block instances are not produced when the program is compiled.
After function block A is declared in a certain POU of the program type or in a the global symbol table in a project, the corresponding function block instances will be produced according to the relation among the three function blocks during the compiling of the program. Please refer to the declaration of the function block instances and the relation among the function blocks below. Function block D is declared in the global symbol table while the other function block instances are declared in the local symbol tables in the superior POUs (callers). 7-22 Declaration position Function block which is declared Global symbol table One instance of function block D:
INS D _ Local symbol table POU of the program type One instance of function block A: INS A _ One instance of function block B: INS B _ Function block A One instance of function block B: INS B _ Function block B Two instances of function block C: INS C1 and INS C2 _ _