Design, Testing and Implementation

The different phases of the often laborious process of the design and realization of industrial logic control systems are efficiently integrated by the software package LogSim.

The traditional design process (somewhat simplified) starts with setting up the logic elements and their connections with pencil on paper, based upon the functional requirements. As long as the scheme fits on one piece of paper, the functions can easily be understood. However, as the logic grows, it will be harder to check whether the functions are as required.

When the sketches are ready, the draftsmen make neat drawings, and the programmer starts. He translates the symbols and the signal connections into a program for the PLC (Programmable Logic Controller).
For the functional test switches (or electronic equivalents) are connected to the inputs and signal lights to the outputs. The test consists of observing of the states of the lights for different combinations of the input states en comparing them with the original functional requirements. A medium size logic (a few hundreds of gates) is hardly never error free for the first time. The drawings must be corrected, subsequently also the program, and the test can start again.
The problem is caused by the fact that people from different disciplines (often of different companies) are working on the project, and that errors can first be detected in the final phase.