1.3 Subroutine execution You can use subroutines in the Lua program to simplify the program for easy maintenance and development. In the Main program, you can use a “require” instruction to load the subroutine. Please refer to Table 1.4 Subroutine execution example. Table 1.4 Subroutine execution example 22 1. Lua programming Edit [Main] program Step 1: double-click [Main] in the DOPSoft project tree to enter the editing interface.