There are certain control systems that cannot be disabled or shut down, even momentarily, because of the threat to people’s lives. In these applications, a redundant control system must be in place to take over instantaneously if the primary system fails.
DMC programmed a redundant SCADA system to control a train tunnel ventilation system. Twenty S7-300 PLC's control about 4000 IO (Input/Output) points. These IO points consist mainly of fans and dampers distributed throughout the train tunnel. The S7-400H Redundant PLC communicates with these twenty S7-300 PLC's via TCP. The S7-400H PLC also retrieves train information data through Modbus TCP. In the event of a fire, the redundant PLC will determine which fans and dampers to actuate based on train information and operator input.
A redundant HMI system was programmed with Siemens WinCC. The HMI displays the process graphically, logs errors, operator interactions, events, and alarms into various databases.
Using IEC 61131-3 programming principles, a simulation mode was easily implemented in the system. This mode simulates the entire system and runs in parallel to the actual physical system. It permits operator training without turning on actual fans and dampers. If an incident occurs, the simulation mode immediately switches back to the live system and alerts the operators.
Learn more about DMC's HMI and SCADA programming services.