1.6. State Transition Logic

The programming methods described above serve well for designing relatively simple systems, for example, a single machine using some form of process sensor. In that case, the sensor is connected and an interrupt task, and the non-interrupt portion of the program is used to operate the machine tool. This level of complexity provides an excellent introduction to the operation of basic manufacturing equipment.

When more complex problems are encountered, however, these software methods do not give enough organizational support to the design or implementation process. Further organizational support is needed for the production of software that is reliable and easily maintained, and, also, is portable across a variety of computing environments [Auslander et al, 1993]. The organization is accomplished by separating the engineering themes associated with the design from the computational implementation issues. Each of these is then separated into two levels: