Environment and facility monitoring systems (EFMS) are essential for the public safety. Typical examples include tunnel monitoring, river pumping stations and waste water treatment. These applications are usually related to government public engineering projects, designed by government departments or engineering companies.
For the tunnel monitoring, the major tasks involve control air quality and lighting control. For river pumping stations, its purpose is to avoid floods when heavy rain falls in the city. So the water level of the river inside the city should be monitored carefully. When the water level exceeds safety limit, the pump in the local river pumping station must start.
I/O functions for these applications are usually very simple. The main challenge is to integrate I/O control with audio and video surveillance. Since these applications are related to public safety, the controller must work all the time. Therefore, controller reliability is a key issue. Advantech’s APAX backup system has two controllers, installed with the same control algorithm. One controller will automatically become the master controller, and the backup controller will take control responsibility when the master controller fails.
Environment and facility monitoring are typical SCADA applications. There are many RTU controller stations installed at each area. Communication interface is another critical function that can people can monitor and control remotely.

APAX-5000 architecture provides two independent controllers, and each controller has its own processor, power supply, communication ports and backplane. It is a warm-start backup system. With two APAX-5520KW controllers, the backup system features a compact size that features easy installation and configuration. Adding a powerful APAX-5570XPE or APAX-5571XPE with two APAX-5520KW backup systems, all functions including I/O control, audio and video application can be covered.

APAX backup systems include one controller (the master controller) that will execute control functions, while the other controller (the backup controller) continues monitoring the master controller. When the backup controller can’t receive messages from the master controller, the program will automatically run on the backup controller, making the backup controller the master controller. Since all mechanisms are automatic, it can be operated in an unmanned environment. This makes the system much more reliable because the system won't be stopped if the controller fails.