PLC-integrated Process Monitoring and Prediction of the Resulting Real-Time Load

Nowadays process data acquisition in automated installations is essential for efficient fault diagnosis during development and commissioning, but also for quality assurance, optimization and documentation. Classical solutions for monitoring of real-time PLC (programmable logic controller) devices lack flexibility and sampling resolution. Therefore this paper presents an approach, where an additional software entity ("monitoring agent") is dynamically installed onto the PLC for process data acquisition. Special attention will be paid to the real-time load caused by the monitoring software running parallel to time critical tasks in the PLC. The paper refers to a practical implementation for Siemens SIMATIC S7-300/400 PLCs, which is part of the tool "Analyzer AutoSPy".