Remote Automation Laboratory Using a Cluster of Virtual Machines

This paper presents a remote laboratory for industrial automation comprising different programmable logic controller (PLC) manufacturers. This facility provides an environment for remote users to learn many automation topics while using different PLCs together with several types of sensors, actuators, and industrial communication networks. The laboratory architecture that makes up the remote automation laboratory (RAL) is based on a Moodle-server master PC (MPC), which also manages the booking system of PLC benches available in the laboratory. There exist a cluster of virtual machines (VMs) running on several slave PCs (SPCs), four VMs per SPC. Each VM can manage a type of PLC bench of the automation laboratory. The MPC server balances the load of SPCs allowing the implementation and easy upgrading of the RAL offering different PLCs at the same time within the same remote interface. The remote laboratory has Internet protocol cameras providing a view of the real environment of each PLC bench to the remote user. The authentication system and management of remote users and PLC benches are made via Moodle plug-ins and hypertext preprocessor (PHP) scripts. Two external/internal routers dynamically configure the remote users' access to a particular PLC bench. RAL architecture can be applied to other e-learning areas.