Web Monitoring System and Gateway for Serial Communication PLC

An industrial process requires interacting with the rest of the plant, being able to exchange data with other devices and monitoring systems in order to optimize production, reporting information and providing control capabilities to distant users. Internet, and, especially web browsers are an excellent tool to provide information for remote users, allowing not only monitoring but also controlling the industrial process as an SCADA software or HMI system. The proposed system does not need specific proprietary software and its associated license costs. In this work, a webserver system is implemented under a Freescale microcontroller, acting as a gateway for a simple PLC with single RS232 communication capabilities. The webserver is modular, providing independent access to single I/O PLC locations. Different webpage design can offer different monitoring capabilities by combining the required I/O modules according to the required application without any change in the microcontroller programming. This capability is close to SCADA software or industrial HMI systems where custom screens can be made. This proposal offers a low cost and flexible monitoring solution to old or basic industrial processes controlled by PLC with low communication capabilities. Using a web browser, the system can be monitored from any internet capable device: PC, tablet, smartphone, etc. An example for a pneumatic PID levitation control system is given.