SCADA subsystem for early warning detection of a critical situation is developed with the intention of the monitoring production process in real-time, and generate a warning to the user before critical condition appears. In order to do so, critical condition(event) models are stored in a database, containing all relevant signals participating in each observed critical condition individually. The system in question is developed as a web application and I/O server application in two separate modules. While the web application is concerned for the execution of the real-time calculation, detection of conditions approaching stored critical situation model and graphical presentation, the function of I/O server is real-time data collection form PLC and storing in SQL database. The main advantage of the described system is its flexibility in relation to existing SCADA systems that might be in use. There are no special requests regarding data transfer protocol or database compatibility. Also, there is no need for client application software installation on any PC that is to be used to access the application. This can be simply done via a web browser.