A subroutine can be called by another what in the context of PLC programming?

In the context of PLC programming, a subroutine is typically called by another routine. This is because routines serve as blocks of code designed to perform specific functions or operations. They can include main program routines as well as subroutines, which allow for modular and organized coding practices. When one routine calls another, it can execute the sequence of instructions defined within the subroutine, making code more reusable and easier to manage.

The concept of routines in PLC programming emphasizes breaking down complex processes into smaller, manageable segments that can be individually tested and maintained. This enhances the overall readability and efficiency of the program while facilitating debugging and updates.

Additionally, while functions, tasks, and processes are relevant terms within the broader scope of programming and automation, they do not directly align with the concept of a subroutine calling mechanism in PLC programming as defined by the terminology typically used in this context.