Implementation and performance evaluation of Profibus in the automation systems

Profibus interface S/W is implemented on a PC and embedded controller. In order to enable the Profibus interface S/W to handle many application tasks and communication services, two kinds of real time/multi tasking operating system, CTask and OS-9, are utilized. Using the Profibus interface S/W, the study develops an experimental model of an automation system, and evaluates the message delay in the user layer. The message delay is measured with respect to the changes of message length, message generation period and TRT (Token Rotation Time). The outcomes of the experiment are compared with those of the simulation model which comprise only the physical and data link layers of Profibus. The study investigates the relationship between the message delay in the data link layer and the message delay up to the user layer. Based on the results, the study suggests some factors that should be considered when a Profibus based automation system is designed and implemented.