Software aspects of integrating several separately controlled machines into one control system-PLC example

In the early 1980´s relatively powerful, yet inexpensive, microprocessors became available for use in machine control systems. Typically, they were applied to control one or two joints or axes of motion. The coordination of movement for more complex machines was accomplished via intercontroller communication, usually between I/O. Often these controllers were proprietary, custom designed and build. As more capable off-the-shelf controllers became available, e.g. in the form of PLCs or lately, Industrial PCs, they were used to control several or all of machine´s axes of motion. The present day trend is to integrate several machines operating in the same workspace, especially in semi-automatic mode, into one controller. The integration of controls can be made easier with proper planning and some forethought in developing the software for individual devices. Examples of useful practices include generation of typical parts of a program, developing structure and organization of a program which is suitable for mix-and-match combining of these parts, and naming conventions of variables and program parts