Abstract: A table of sequential call statements is used to organize various program portions of the operating system of an industrial controller. This organizing structure allows troubleshooting of individual program portions of the operating system as are intimately related to the controlled process and the control hardware on an individual basis without the need to generate dummy programs or “stubs” to replace the unexecuted program portions. Those program portions not being executed have their call instructions replaced by NOP instructions. The call table may be edited to provide for different operating modes of the industrial controller without the need for mode test flags otherwise dispersed within the program code of the operating system.