Estimating micro-PLC execution time for time critical system design

In this paper, we propose a method for estimating the PLC (Programmable Logic Controller) program execution time, using the informations available at the design stage. So far, the usual practice is to check execution time after complete development of PLC application program. In case, the developed PLC program does not meet the required response time, it is interactively modified. This situation can be avoided to a great extent with our proposed estimation method. We calculate the maximum theoretical execution time and later refine it using application statistics. Preliminary applications of our method show encouraging results.