PLC-based elevator group control

The project

For the 2024 18th CIMC “Siemens Cup” China Intelligent Manufacturing Challenge, our three-person team developed a three-elevator, ten-floor group-control system in the Discrete Industry Automation / Logic Algorithm category.

I carried out the main control-software development, supervisory-interface work and integration. The system combined individual elevator operation and protection with group dispatch and traffic-dependent scheduling.

My contribution

• Single-elevator logic. Developed initialisation, collective selective control, automatic levelling, door operation, weight-related detection and three-stage braking/start–stop logic.
• Protection and operating modes. Implemented invalid-command elimination, idle/sleep behaviour, overload and terminal-overtravel protection, abnormal-state handling, maintenance and inspection modes.
• Group scheduling. Designed weighted dispatch using distance, direction, operating state and load-related factors to coordinate the three elevators.
• Traffic adaptation. Used hall calls and in-car requests to detect peak conditions and switch scheduling strategies.
• Supervisory interface. Developed WinCC Advanced monitoring with user authentication, fault alarms, historical information, logs and debugging functions.

Control and coordination

The system used a Siemens S7-1200 CPU 1214C, programmed in LAD and SCL with TIA Portal V18 and STEP7 Professional. Individual-car logic manages movement, doors and protection; the group scheduler evaluates requests alongside each elevator’s operating state.

The weighted strategy considers waiting time, transport efficiency, throughput and energy-related objectives. Traffic-state detection allows the system to switch dispatch strategies, while WinCC makes the operating state available through a supervisory interface.

Team outcome

Our entry received National Finals Second Prize, 41st place, Top 2.71%. The team completed the control and monitoring system for the March–August 2024 competition period, with my work centred on the main development, debugging and integration.