基于PLC的电梯控制系统文献(2)

derived from control cabinet was delivered to tow electric motors. Others control lines and signal lines were separately sent to each floor junction.

The design includes two parts: hardware and software. The hardware design is the base of software. Considering that the control demands are relatively complex, we design the programs separately according to the control function. Furthermore, we follow the principle as follows: When the elevator is ascending, the ascending demands are prior to other demands.When the elevator is descending, the descending demands are prior to other demands. The Sequential Function Chart(SFC) is adopted during the boxes to form elevator’s executive circuitry design. It is a method specially used in industrial sequential control. The SFC method can describe the system’s working procedure in great detail.

When all SFC are drawn and I/O address lists are presented, we can convert the SFC to Ladder Diagram(LD). Considering the strict demands for time and for locked each other, we introduce working bits to remember working steps. We should write out the working bits control program, which can link together each step and make the pervious step as the next step restriction condition. Thus the actual outputs are the logic combination of these working steps.

The system program has been debugged completely at present. Simulated experiment enunciates that the design method is viable. Application of PLC in the elevator control system is an effective method. It can make the personnel of the industry management center to long-distance monitor and control the elevator in control center, to connect the elevator system with intelligence building industry management system by Ethernet or special-purpose network such as Lon Works. The elevator, but also can lower the elevator maintenance costs etc. It is one of the developing direction of intelligence building elevator control system.

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